chore: Release lemur version 0.15.1

- Support WGPU_FORCE_FALLBACK to run on CPU
 - Pass display when creating wgpu instance
 - Pass compatible surface when constructing adapter
 - Log some settings (at debug level)

Cargo.toml

@@ -4,49 +4,49 @@ description = "An emulator for the Virtual Boy."
 repository = "https://git.virtual-boy.com/PVB/lemur"
 publish = false
 license = "MIT"
-version = "0.12.0"
+version = "0.15.1"
 edition = "2024"
 
 [dependencies]
 anyhow = "1"
-atoi = "2"
-audioadapter-buffers = "3"
+atoi = "3"
+audioadapter-buffers = "5"
 atomic = "0.6"
 bitflags = { version = "2", features = ["serde"] }
 bytemuck = { version = "1", features = ["derive"] }
 clap = { version = "4", features = ["derive"] }
-cpal = { git = "https://github.com/sidit77/cpal.git", rev = "66ed6be" }
+cpal = "0.18"
 directories = "6"
-egui = { version = "0.34", features = ["persistence", "serde"] }
-egui_extras = { version = "0.34", features = ["image"] }
-egui-notify = "0.22"
-egui-winit = "0.34"
-egui-wgpu = { version = "0.34", features = ["winit"] }
+egui = { version = "0.36", features = ["persistence", "serde"] }
+egui_extras = { version = "0.36", features = ["image"] }
+egui-notify = "0.23"
+egui-winit = "0.36"
+egui-wgpu = { version = "0.36", features = ["winit"] }
 fxprof-processed-profile = "0.8"
 fixed = { version = "1.28", features = ["num-traits"] }
 gilrs = { version = "0.11", features = ["serde-serialize"] }
-gimli = "0.33"
+gimli = "0.34"
 hex = "0.4"
 image = { version = "0.25", default-features = false, features = ["png"] }
-itertools = "0.14"
+itertools = "0.15"
 normpath = "1"
 notify = "8"
-num-derive = "0.4"
+num-derive = "0.5"
 num-traits = "0.2"
-object = "0.39"
+object = "0.40"
 oneshot = { version = "0.2", features = ["async", "std"] }
-pollster = "0.4"
+pollster = "1"
 rand = "0.10"
 rfd = "0.17"
-rtrb = "0.3"
-rubato = "2"
+rtrb = "0.4"
+rubato = "5"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 thread-priority = "3"
 tokio = { version = "1", features = ["io-util", "macros", "net", "rt", "sync", "time"] }
-tracing = { version = "0.1", features = ["release_max_level_info"] }
+tracing = { version = "0.1", features = ["release_max_level_debug"] }
 tracing-subscriber = { version = "0.3", features = ["env-filter"] }
-wgpu = "29"
+wgpu = { version = "30", features = ["serde"] }
 wholesym = "0.8"
 winit = { version = "0.30", features = ["serde"] }
 

build.Dockerfile

@@ -1,7 +1,7 @@
 # This Dockerfile produces a base image for builds.
 # It includes all dependencies necessary to cross-compile for Windows/MacOS/Linux.
 
-FROM debian:bookworm AS osxcross
+FROM debian:trixie AS osxcross
 ADD --chmod=644 "https://apt.llvm.org/llvm-snapshot.gpg.key" /etc/apt/trusted.gpg.d/apt.llvm.org.asc
 WORKDIR /build/osxcross
 ADD "https://github.com/tpoechtrager/osxcross.git#47936a512273bb3b414b5a2e83043c92eabc7ae7" .
@@ -9,35 +9,31 @@ ADD "https://github.com/joseluisq/macosx-sdks/releases/download/14.5/MacOSX14.5.
 RUN apt-get update && \
     apt-get install -y ca-certificates
 COPY llvm.sources /etc/apt/sources.list.d/llvm.sources
-COPY install-llvm.sh .
 RUN apt-get update && \
-    ./install-llvm.sh && \
-    apt-get install -y bash bzip2 git make patch xz-utils && \
-    ln -s $(which clang-21) /usr/bin/clang && \
-    ln -s $(which clang++-21) /usr/bin/clang++ && \
-    ln -s $(which ld64.lld-21) /usr/bin/ld64.lld && \
+    apt-get install -y bash bzip2 clang-22 git lld-22 llvm-22 make patch xz-utils && \
+    ln -s $(which clang-22) /usr/bin/clang && \
+    ln -s $(which clang++-22) /usr/bin/clang++ && \
+    ln -s $(which ld64.lld-22) /usr/bin/ld64.lld && \
     SDK_VERSION=14.5 UNATTENDED=1 ENABLE_COMPILER_RT_INSTALL=1 TARGET_DIR=/osxcross ./build.sh
 
-FROM rust:1.94-bookworm
+FROM rust:1.98-trixie
 ADD --chmod=644 "https://apt.llvm.org/llvm-snapshot.gpg.key" /etc/apt/trusted.gpg.d/apt.llvm.org.asc
 COPY llvm.sources /etc/apt/sources.list.d/llvm.sources
-COPY install-llvm.sh .
 RUN rustup target add x86_64-pc-windows-msvc && \
     rustup target add x86_64-apple-darwin && \
     rustup target add aarch64-apple-darwin && \
     apt-get update && \
-    ./install-llvm.sh && \
-    apt-get install -y libc6-dev libasound2-dev libudev-dev genisoimage mingw-w64 && \
+    apt-get install -y clang-22 lld-22 libc6-dev libasound2-dev libudev-dev genisoimage mingw-w64 && \
     cargo install cargo-bundle xwin && \
     xwin --accept-license splat --output xwin && \
     rm -rf .xwin-cache && \
-    ln -s $(which clang-21) /usr/bin/clang && \
-    ln -s $(which clang++-21) /usr/bin/clang++
+    ln -s $(which clang-22) /usr/bin/clang && \
+    ln -s $(which clang++-22) /usr/bin/clang++
 COPY --from=osxcross /osxcross /osxcross
 
 ENV PATH="/osxcross/bin:$PATH" \
     LD_LIBRARY_PATH="/osxcross/lib" \
-    CC="clang-21" CXX="clang++-21" AR="llvm-ar-21" \
+    CC="clang-22" CXX="clang++-22" AR="llvm-ar-22" \
     CC_x86_64-apple-darwin="o64-clang" \
     CXX_x86_64-apple-darwin="o64-clang++" \
     CC_aarch64-apple-darwin="oa64-clang" \
@@ -47,11 +43,11 @@ ENV PATH="/osxcross/bin:$PATH" \
     SHROOMS_CFLAGS_x86_64-pc-windows-msvc="-flto" \
     CFLAGS_x86_64-pc-windows-msvc="-I/xwin/crt/include -I/xwin/sdk/include/ucrt -I/xwin/sdk/include/um -I/xwin/sdk/include/shared" \
     CARGO_TARGET_X86_64_PC_WINDOWS_MSVC_RUSTFLAGS="-Lnative=/xwin/crt/lib/x86_64 -Lnative=/xwin/sdk/lib/um/x86_64 -Lnative=/xwin/sdk/lib/ucrt/x86_64 -Clinker-plugin-lto -Clink-arg=-fuse-ld=lld" \
-    CARGO_TARGET_X86_64_PC_WINDOWS_MSVC_LINKER="lld-link-21" \
+    CARGO_TARGET_X86_64_PC_WINDOWS_MSVC_LINKER="lld-link-22" \
     CARGO_TARGET_X86_64_APPLE_DARWIN_LINKER="o64-clang" \
-    CARGO_TARGET_X86_64_APPLE_DARWIN_AR="llvm-ar-21" \
+    CARGO_TARGET_X86_64_APPLE_DARWIN_AR="llvm-ar-22" \
     CARGO_TARGET_AARCH64_APPLE_DARWIN_LINKER="oa64-clang" \
-    CARGO_TARGET_AARCH64_APPLE_DARWIN_AR="llvm-ar-21" \
-    RC_PATH="llvm-rc-21" \
+    CARGO_TARGET_AARCH64_APPLE_DARWIN_AR="llvm-ar-22" \
+    RC_PATH="llvm-rc-22" \
     MACOSX_DEPLOYMENT_TARGET="14.5"
 ENTRYPOINT ["bash"]

install-llvm.sh

@@ -1,19 +0,0 @@
-#!/usr/bin/env bash
-
-# Hopefully temporary script to manually install working llvm packages.
-# The apt index for these is broken in bookworm, and upgrading to trixie
-# would make them depend on too new of a libc version.
-
-# https://apt.llvm.org/bookworm/pool/main/l/llvm-toolchain-21/clang-21_21.1.5~%2B%2B20251023083151%2B45afac62e373-1~exp1~20251023083333.51_amd64.deb
-PACKAGES=('clang-21' 'clang-tools-21' 'libclang-common-21-dev' 'libclang-cpp21' 'libclang-rt-21-dev' 'libclang1-21' 'libllvm21' 'lld-21' 'llvm-21' 'llvm-21-dev' 'llvm-21-linker-tools' 'llvm-21-runtime' 'llvm-21-tools')
-FILES=()
-URL='https://apt.llvm.org/bookworm/pool/main/l/llvm-toolchain-21'
-VERSION='21.1.5~%2B%2B20251023083151%2B45afac62e373-1~exp1~20251023083333.51_amd64.deb'
-
-apt-get install -y curl python3
-for package in "${PACKAGES[@]}"; do
-    curl -O -L "$URL/${package}_$VERSION"
-    FILES+=("./${package}_$VERSION")
-done
-
-apt-get install -y "${FILES[@]}"

llvm.sources

@@ -1,4 +1,4 @@
 Types: deb deb-src
-URIs: http://apt.llvm.org/bookworm/
-Suites: llvm-toolchain-bookworm-21
+URIs: http://apt.llvm.org/trixie/
+Suites: llvm-toolchain-trixie-22
 Components: main

src/app.rs

@@ -14,22 +14,22 @@ use egui::{
 use egui_wgpu::winit::Painter;
 use egui_winit::EventResponse;
 use gilrs::{EventType, Gilrs};
-use tracing::{error, warn};
+use tracing::{debug, error, warn};
 use winit::{
     application::ApplicationHandler,
     event::WindowEvent,
-    event_loop::{ActiveEventLoop, ControlFlow, EventLoopProxy},
+    event_loop::{ActiveEventLoop, ControlFlow, EventLoopProxy, OwnedDisplayHandle},
     window::{Window, WindowId},
 };
 
 use crate::{
-    config::CliArgs,
+    config::{AppConfig, CliArgs},
     controller::ControllerManager,
     emulator::{EmulatorClient, EmulatorCommand, SimId},
+    filesystem::Persistence,
     images::ImageTextureLoader,
     input::{MappingProvider, ShortcutProvider},
     memory::MemoryClient,
-    persistence::Persistence,
     window::{AppWindow, ChildWindow, GameScreen, GameWindow, InitArgs},
 };
 
@@ -48,9 +48,30 @@ fn load_icon() -> anyhow::Result<IconData> {
 
 struct SharedViewportState {
     viewport_info: ViewportIdMap<ViewportInfo>,
-    painter: Painter,
+    wgpu: WgpuState,
+    painter: Option<Painter>,
     resized_viewport: Option<ViewportId>,
 }
+impl SharedViewportState {
+    fn init_painter(&mut self, ctx: &Context, window: &Window) -> &mut Painter {
+        if self.painter.is_none() {
+            let wgpu_config = egui_wgpu::WgpuConfiguration {
+                surface: egui_wgpu::SurfaceConfig::HIGH_THROUGHPUT,
+                wgpu_setup: egui_wgpu::WgpuSetup::Existing(self.wgpu.init(window)),
+                ..egui_wgpu::WgpuConfiguration::default()
+            };
+
+            let options = egui_wgpu::RendererOptions::default();
+            let painter =
+                pollster::block_on(Painter::new(ctx.clone(), wgpu_config, false, options));
+            self.painter = Some(painter);
+        }
+        self.painter.as_mut().unwrap()
+    }
+    fn get_painter(&mut self) -> &mut Painter {
+        self.painter.as_mut().unwrap()
+    }
+}
 
 pub struct Application {
     client: EmulatorClient,
@@ -70,10 +91,12 @@ impl Application {
     pub fn new(
         client: EmulatorClient,
         proxy: EventLoopProxy<UserEvent>,
+        handle: OwnedDisplayHandle,
         persistence: Persistence,
         args: CliArgs,
+        config: AppConfig,
     ) -> Self {
-        let wgpu = WgpuState::new();
+        let wgpu = WgpuState::new(handle, config);
         let icon = load_icon().ok().map(Arc::new);
         let mappings = MappingProvider::new(persistence.clone(), args.player2_controller);
         let shortcuts = ShortcutProvider::new(persistence.clone());
@@ -131,20 +154,6 @@ impl Application {
             });
         }
 
-        let wgpu_config = egui_wgpu::WgpuConfiguration {
-            present_mode: wgpu::PresentMode::AutoVsync,
-            wgpu_setup: egui_wgpu::WgpuSetup::Existing(egui_wgpu::WgpuSetupExisting {
-                instance: wgpu.instance.clone(),
-                adapter: wgpu.adapter.clone(),
-                device: wgpu.device.clone(),
-                queue: wgpu.queue.clone(),
-            }),
-            ..egui_wgpu::WgpuConfiguration::default()
-        };
-
-        let options = egui_wgpu::RendererOptions::default();
-        let painter = pollster::block_on(Painter::new(ctx.clone(), wgpu_config, false, options));
-
         let mut initial_windows = vec![];
         if let Some(port) = args.debug_port {
             initial_windows.push(ChildWindow::Debugger { port: Some(port) });
@@ -184,7 +193,8 @@ impl Application {
             ctx,
             shared: SharedViewportState {
                 viewport_info: ViewportIdMap::default(),
-                painter,
+                wgpu,
+                painter: None,
                 resized_viewport: None,
             },
             icon,
@@ -247,7 +257,7 @@ impl Application {
                 continue;
             }
             input.viewports = self.shared.viewport_info.clone();
-            let output = self.ctx.run_ui(input, |ui| {
+            let mut output = self.ctx.run_ui(input, |ui| {
                 if viewport.id == ViewportId::ROOT {
                     self.app.show(ui);
                 } else if let Some(cb) = ui.viewport(|v| v.viewport_ui_cb.clone()) {
@@ -288,15 +298,16 @@ impl Application {
                 }
             }
             let clipped_primitives = self.ctx.tessellate(output.shapes, output.pixels_per_point);
-            self.shared.painter.paint_and_update_textures(
+            viewport.window.pre_present_notify();
+            self.shared.get_painter().paint_and_update_textures(
                 viewport.id,
                 output.pixels_per_point,
                 [0.0, 0.0, 0.0, 0.0],
                 &clipped_primitives,
-                &output.textures_delta,
+                &mut output.textures_delta,
                 vec![],
+                &viewport.window,
             );
-            viewport.window.pre_present_notify();
         }
         let mut active_viewports = ViewportIdSet::default();
         for (id, update) in updates {
@@ -325,7 +336,11 @@ impl Application {
                                 id,
                                 InitArgs {
                                     window: &manager.window,
-                                    render_state: &self.shared.painter.render_state().unwrap(),
+                                    render_state: &self
+                                        .shared
+                                        .get_painter()
+                                        .render_state()
+                                        .unwrap(),
                                 },
                             );
                             manager
@@ -341,7 +356,9 @@ impl Application {
         if !active_viewports.contains(&ViewportId::ROOT) {
             event_loop.exit();
         }
-        self.shared.painter.gc_viewports(&active_viewports);
+        if let Some(painter) = self.shared.painter.as_mut() {
+            painter.gc_viewports(&active_viewports);
+        }
     }
 }
 
@@ -359,7 +376,7 @@ impl ApplicationHandler<UserEvent> for Application {
             viewport_builder,
             &mut self.shared,
         );
-        let render_state = self.shared.painter.render_state().unwrap();
+        let render_state = self.shared.get_painter().render_state().unwrap();
         GameScreen::init_pipeline(&render_state);
         self.app.handle_init(
             ViewportId::ROOT,
@@ -398,22 +415,28 @@ impl ApplicationHandler<UserEvent> for Application {
         if close_requested && viewport_id == ViewportId::ROOT {
             event_loop.exit();
         }
+        if response.repaint {
+            viewport.window.request_redraw();
+        }
         if !response.consumed {
             match event {
-                WindowEvent::KeyboardInput { event, .. } => {
-                    if !self.app.handle_key_event(viewport_id, &event) {
+                WindowEvent::KeyboardInput { event, .. }
+                    if !self.app.handle_key_event(viewport_id, &event) =>
+                {
                     self.controllers.handle_key_event(&event);
                 }
+                WindowEvent::DroppedFile(path) => {
+                    self.app.handle_dropped_file(viewport_id, path);
                 }
                 WindowEvent::Focused(new_focused) => {
                     self.focused = new_focused.then_some(viewport_id);
                 }
+                WindowEvent::RedrawRequested => {
+                    self.repaint_all(event_loop);
+                }
                 _ => {}
             }
         }
-        if response.repaint {
-            self.repaint_all(event_loop);
-        }
         self.check_repaint(event_loop);
     }
 
@@ -445,6 +468,9 @@ impl ApplicationHandler<UserEvent> for Application {
                     self.controllers.handle_gamepad_event(&event);
                 }
             }
+            UserEvent::LowBattery(sim_id, pwr) => {
+                self.controllers.handle_low_battery(sim_id, pwr);
+            }
             UserEvent::Quit(sim_id) => match sim_id {
                 SimId::Player1 => event_loop.exit(),
                 SimId::Player2 => self.app.close(ChildWindow::Player2),
@@ -477,47 +503,67 @@ impl ApplicationHandler<UserEvent> for Application {
 
 struct WgpuState {
     instance: wgpu::Instance,
-    adapter: wgpu::Adapter,
-    device: wgpu::Device,
-    queue: wgpu::Queue,
+    device_descriptor: Arc<dyn Fn(&wgpu::Adapter) -> wgpu::DeviceDescriptor<'static> + Send + Sync>,
+    config: AppConfig,
 }
 
 impl WgpuState {
-    fn new() -> Self {
+    fn new(handle: OwnedDisplayHandle, config: AppConfig) -> Self {
         #[allow(unused_variables)]
-        let egui_wgpu::WgpuConfiguration {
-            wgpu_setup:
-                egui_wgpu::WgpuSetup::CreateNew(egui_wgpu::WgpuSetupCreateNew {
+        let egui_wgpu::WgpuSetupCreateNew {
             instance_descriptor: wgpu::InstanceDescriptor { backends, .. },
             device_descriptor,
             ..
-                }),
-            ..
-        } = egui_wgpu::WgpuConfiguration::default()
-        else {
-            panic!("required fields not found")
-        };
+        } = egui_wgpu::WgpuSetupCreateNew::without_display_handle();
         #[cfg(windows)]
         let backends = wgpu::Backends::from_env()
             .unwrap_or((wgpu::Backends::PRIMARY | wgpu::Backends::GL) - wgpu::Backends::VULKAN);
         let instance = wgpu::Instance::new(wgpu::InstanceDescriptor {
             backends,
-            ..wgpu::InstanceDescriptor::new_without_display_handle_from_env()
+            ..wgpu::InstanceDescriptor::new_with_display_handle_from_env(Box::new(handle))
         });
 
-        let adapter = pollster::block_on(instance.request_adapter(&wgpu::RequestAdapterOptions {
-            power_preference:
-                wgpu::PowerPreference::from_env().unwrap_or(wgpu::PowerPreference::LowPower),
-            compatible_surface: None,
-            force_fallback_adapter: false,
-        }))
-        .expect("could not create adapter");
-
-        let (device, queue) =
-            pollster::block_on(adapter.request_device(&(*device_descriptor)(&adapter)))
-                .expect("could not request device");
         Self {
             instance,
+            device_descriptor,
+            config,
+        }
+    }
+
+    fn init(&mut self, window: &Window) -> egui_wgpu::WgpuSetupExisting {
+        let power_preference =
+            wgpu::PowerPreference::from_env().unwrap_or(self.config.power_preference);
+        debug!("power preference: {power_preference:?}");
+
+        let force_fallback_adapter = std::env::var("WGPU_FORCE_FALLBACK")
+            .map_or(self.config.force_fallback, |f| {
+                f.eq_ignore_ascii_case("true") || f.eq_ignore_ascii_case("1")
+            });
+        debug!("force fallback: {force_fallback_adapter}");
+
+        let surface = self
+            .instance
+            .create_surface(window)
+            .expect("could not create surface");
+
+        let adapter =
+            pollster::block_on(self.instance.request_adapter(&wgpu::RequestAdapterOptions {
+                power_preference,
+                compatible_surface: Some(&surface),
+                force_fallback_adapter,
+                apply_limit_buckets: false,
+            }))
+            .expect("could not create adapter");
+        debug!("selected adapter: {:?}", adapter.get_info());
+
+        drop(surface);
+
+        let (device, queue) =
+            pollster::block_on(adapter.request_device(&(*self.device_descriptor)(&adapter)))
+                .expect("could not request device");
+
+        egui_wgpu::WgpuSetupExisting {
+            instance: self.instance.clone(),
             adapter,
             device,
             queue,
@@ -541,14 +587,15 @@ impl ViewportManager {
         shared: &mut SharedViewportState,
     ) -> Self {
         let window = Arc::new(egui_winit::create_window(ctx, event_loop, &builder).unwrap());
-        pollster::block_on(shared.painter.set_window(viewport_id, Some(window.clone()))).unwrap();
+        let painter = shared.init_painter(ctx, &window);
+        pollster::block_on(painter.set_window(viewport_id, Some(window.clone()))).unwrap();
         let state = egui_winit::State::new(
             ctx.clone(),
             viewport_id,
             event_loop,
             Some(window.scale_factor() as f32),
             event_loop.system_theme(),
-            shared.painter.max_texture_side(),
+            painter.max_texture_side(),
         );
 
         let mut info = ViewportInfo {
@@ -585,9 +632,13 @@ impl ViewportManager {
         {
             if shared.resized_viewport != Some(self.id) {
                 shared.resized_viewport = Some(self.id);
-                shared.painter.on_window_resize_state_change(self.id, true);
+                shared
+                    .get_painter()
+                    .on_window_resize_state_change(self.id, true);
             }
-            shared.painter.on_window_resized(self.id, width, height);
+            shared
+                .get_painter()
+                .on_window_resized(self.id, width, height);
         }
         let response = self.state.on_window_event(&self.window, event);
         let info = shared.viewport_info.get_mut(&self.id).unwrap();
@@ -627,6 +678,7 @@ impl ViewportManager {
 pub enum UserEvent {
     GamepadEvent(gilrs::Event),
     Quit(SimId),
+    LowBattery(SimId, bool),
     RequestRedraw(ViewportId, Instant),
 }
 

src/audio.rs

@@ -1,12 +1,16 @@
 use std::time::Duration;
 
-use anyhow::{Result, bail};
+use anyhow::{Context, Result, bail};
 use audioadapter_buffers::direct::InterleavedSlice;
-use cpal::traits::{DeviceTrait, HostTrait, StreamTrait};
-use rubato::Resampler;
-use tracing::error;
+use cpal::{
+    Device, FromSample, Sample, SampleFormat, SizedSample, StreamConfig,
+    traits::{DeviceTrait, HostTrait, StreamTrait},
+};
+use itertools::Itertools;
+use rubato::{Adjustable as _, Resampler};
+use tracing::warn;
 
-pub struct Audio {
+struct CpalAudio {
     #[allow(unused)]
     stream: cpal::Stream,
     sampler: rubato::Async<f32>,
@@ -17,20 +21,32 @@ pub struct Audio {
 
 const VB_FREQUENCY: usize = 41700;
 
-impl Audio {
-    pub fn init() -> Result<Self> {
+impl CpalAudio {
+    fn init() -> Result<Self> {
         let host = cpal::default_host();
-        let Some(device) = host.default_output_device() else {
-            bail!("No output device available");
-        };
-        let Some(config) = device
+        let device = host
+            .default_output_device()
+            .context("no output device available")?;
+        let default_rate = device.default_output_config()?.sample_rate();
+
+        let supported_config = device
             .supported_output_configs()?
-            .find(|c| c.channels() == 2 && c.sample_format().is_float())
-        else {
-            bail!("No suitable output config available");
-        };
-        let mut config = config.with_max_sample_rate().config();
-        let resample_ratio = config.sample_rate.0 as f64 / VB_FREQUENCY as f64;
+            .filter(|c| {
+                c.contains_rate(default_rate)
+                    && matches!(
+                        c.sample_format(),
+                        SampleFormat::F32
+                            | SampleFormat::F64
+                            | SampleFormat::I32
+                            | SampleFormat::I16
+                    )
+            })
+            .max_by(|a, b| a.cmp_default_heuristics(b))
+            .context("no suitable output config available")?
+            .with_sample_rate(default_rate);
+        let mut config = supported_config.config();
+
+        let resample_ratio = config.sample_rate as f64 / VB_FREQUENCY as f64;
         let chunk_size = (834.0 * resample_ratio) as usize;
         let sampler = rubato::Async::new_poly(
             resample_ratio,
@@ -42,13 +58,30 @@ impl Audio {
         )?;
         config.buffer_size = cpal::BufferSize::Fixed(sampler.output_frames_max() as u32);
 
+        match supported_config.sample_format() {
+            SampleFormat::F32 if config.channels == 2 => {
+                Self::new_f32_stereo(device, config, sampler)
+            }
+            SampleFormat::F32 => Self::new::<f32>(device, config, sampler),
+            SampleFormat::F64 => Self::new::<f64>(device, config, sampler),
+            SampleFormat::I32 => Self::new::<i32>(device, config, sampler),
+            SampleFormat::I16 => Self::new::<i16>(device, config, sampler),
+            _ => bail!("unsupported sample format"),
+        }
+    }
+
+    fn new_f32_stereo(
+        device: Device,
+        config: StreamConfig,
+        sampler: rubato::Async<f32>,
+    ) -> Result<Self> {
         let input_buffer = Vec::with_capacity(sampler.nbr_channels() * sampler.input_frames_max());
         let output_buffer = vec![0.0; sampler.nbr_channels() * sampler.output_frames_max()];
         let (sample_sink, mut sample_source) =
             rtrb::RingBuffer::new(sampler.output_frames_max() * 4);
 
         let stream = device.build_output_stream(
-            &config,
+            config,
             move |data: &mut [f32], _| {
                 let requested = data.len();
                 let chunk = match sample_source.read_chunk(data.len()) {
@@ -66,7 +99,7 @@ impl Audio {
                 }
                 chunk.commit_all();
             },
-            move |error| error!(%error, "stream error"),
+            move |error| warn!(%error, "stream error"),
             None,
         )?;
         stream.play()?;
@@ -79,7 +112,60 @@ impl Audio {
         })
     }
 
-    pub fn update(&mut self, mut samples: &[f32]) {
+    fn new<S: SizedSample + FromSample<f32>>(
+        device: Device,
+        config: StreamConfig,
+        sampler: rubato::Async<f32>,
+    ) -> Result<Self> {
+        let input_buffer = Vec::with_capacity(sampler.nbr_channels() * sampler.input_frames_max());
+        let output_buffer = vec![0.0; sampler.nbr_channels() * sampler.output_frames_max()];
+        let (sample_sink, mut sample_source) =
+            rtrb::RingBuffer::new(sampler.output_frames_max() * 4);
+
+        let channels = config.channels as usize;
+
+        let stream = device.build_output_stream(
+            config,
+            move |data: &mut [S], _| {
+                let requested = data.len() * 2 / channels;
+                let chunk = match sample_source.read_chunk(requested) {
+                    Ok(c) => c,
+                    Err(rtrb::chunks::ChunkError::TooFewSlots(n)) => {
+                        sample_source.read_chunk(n).unwrap()
+                    }
+                };
+                let (first, second) = chunk.as_slices();
+
+                let new_samples = first
+                    .iter()
+                    .chain(second)
+                    .map(|s: &f32| (*s).to_sample())
+                    .chunks(2);
+                let buffer = data.iter_mut().chunks(channels);
+                for (dst, samples) in buffer.into_iter().zip(&new_samples) {
+                    // channels beyond the first two are zeroed
+                    let src = samples.chain(std::iter::repeat(S::EQUILIBRIUM));
+                    for (d, s) in dst.zip(src) {
+                        *d = s;
+                    }
+                }
+
+                chunk.commit_all();
+            },
+            move |error| warn!(%error, "stream error"),
+            None,
+        )?;
+        stream.play()?;
+        Ok(Self {
+            stream,
+            sampler,
+            input_buffer,
+            output_buffer,
+            sample_sink,
+        })
+    }
+
+    fn update(&mut self, mut samples: &[f32]) {
         while self.input_buffer.len() + samples.len() >= self.sampler.input_frames_next() * 2 {
             let samples_needed =
                 (self.sampler.input_frames_next() * 2).saturating_sub(self.input_buffer.len());
@@ -117,9 +203,64 @@ impl Audio {
         }
     }
 
-    pub fn set_speed(&mut self, speed: f64) -> Result<()> {
+    fn set_speed(&mut self, speed: f64) -> Result<()> {
         self.sampler
             .set_resample_ratio_relative(1.0 / speed, false)?;
         Ok(())
     }
 }
+
+struct NoAudio {
+    speed: f64,
+}
+
+impl NoAudio {
+    fn new() -> Self {
+        Self { speed: 1.0 }
+    }
+
+    fn update(&mut self, samples: &[f32]) {
+        let samples = (samples.len() / 2) as f64;
+        let elapsed = Duration::from_secs_f64(samples / (VB_FREQUENCY as f64 * self.speed));
+        std::thread::sleep(elapsed);
+    }
+
+    fn set_speed(&mut self, speed: f64) -> Result<()> {
+        self.speed = speed;
+        Ok(())
+    }
+}
+
+#[allow(clippy::large_enum_variant)]
+enum AudioInner {
+    Cpal(CpalAudio),
+    None(NoAudio),
+}
+
+pub struct Audio(AudioInner);
+
+impl Audio {
+    pub fn init() -> Self {
+        match CpalAudio::init() {
+            Ok(a) => Self(AudioInner::Cpal(a)),
+            Err(e) => {
+                warn!("could not play audio: {e}");
+                Self(AudioInner::None(NoAudio::new()))
+            }
+        }
+    }
+
+    pub fn update(&mut self, samples: &[f32]) {
+        match &mut self.0 {
+            AudioInner::Cpal(a) => a.update(samples),
+            AudioInner::None(a) => a.update(samples),
+        }
+    }
+
+    pub fn set_speed(&mut self, speed: f64) -> Result<()> {
+        match &mut self.0 {
+            AudioInner::Cpal(a) => a.set_speed(speed),
+            AudioInner::None(a) => a.set_speed(speed),
+        }
+    }
+}

src/config.rs

@@ -1,9 +1,10 @@
 use anyhow::Result;
-use clap::Parser;
-use egui::{Color32, Vec2};
+use bytemuck::NoUninit;
+use clap::{Parser, ValueEnum};
+use egui::{Color32, Pos2, Vec2};
 use serde::{Deserialize, Serialize};
 
-use crate::{emulator::SimId, persistence::Persistence, window::DisplayMode};
+use crate::{emulator::SimId, filesystem::Persistence, window::DisplayMode};
 use std::path::PathBuf;
 
 #[derive(Parser)]
@@ -47,6 +48,31 @@ pub struct CliArgs {
     /// Map the first connected controller to Player 2
     #[arg(long)]
     pub player2_controller: bool,
+    /// Force the application to render with CPU, rather than GPU.
+    #[arg(long)]
+    pub wgpu_force_fallback: Option<bool>,
+    /// Set a preference for whether to use a low-power or high-performance GPU adapter
+    #[arg(long)]
+    pub wgpu_power_preference: Option<PowerPreferenceWrapper>,
+    /// Choose whether save files are kept in the rom or the data directory
+    #[arg(long)]
+    pub save_data_location: Option<SaveDataLocation>,
+}
+
+#[derive(ValueEnum, Clone, Copy)]
+pub enum PowerPreferenceWrapper {
+    Low,
+    High,
+    None,
+}
+impl From<PowerPreferenceWrapper> for wgpu::PowerPreference {
+    fn from(value: PowerPreferenceWrapper) -> Self {
+        match value {
+            PowerPreferenceWrapper::Low => wgpu::PowerPreference::LowPower,
+            PowerPreferenceWrapper::High => wgpu::PowerPreference::HighPerformance,
+            PowerPreferenceWrapper::None => wgpu::PowerPreference::None,
+        }
+    }
 }
 
 pub const COLOR_PRESETS: [[Color32; 2]; 3] = [
@@ -64,6 +90,69 @@ pub const COLOR_PRESETS: [[Color32; 2]; 3] = [
     ],
 ];
 
+const fn default_power_preference() -> wgpu::PowerPreference {
+    wgpu::PowerPreference::LowPower
+}
+
+#[derive(Serialize, Deserialize, Clone, Copy, PartialEq, Eq, ValueEnum, Debug, NoUninit)]
+#[repr(usize)]
+pub enum SaveDataLocation {
+    /// The same directory as the ROM
+    RomDirectory,
+    /// This application's data directory
+    DataDirectory,
+}
+
+const fn default_save_data_location() -> SaveDataLocation {
+    SaveDataLocation::RomDirectory
+}
+
+#[derive(Serialize, Deserialize, Clone, PartialEq, Eq)]
+pub struct AppConfig {
+    #[serde(default = "default_power_preference")]
+    pub power_preference: wgpu::PowerPreference,
+    #[serde(default)]
+    pub force_fallback: bool,
+    #[serde(default = "default_save_data_location")]
+    pub save_data_location: SaveDataLocation,
+}
+
+impl AppConfig {
+    pub fn load(persistence: &Persistence) -> Self {
+        if let Ok(config) = persistence.load_config(APP_CONFIG_FILENAME) {
+            return config;
+        }
+        Self {
+            power_preference: default_power_preference(),
+            force_fallback: false,
+            save_data_location: default_save_data_location(),
+        }
+    }
+
+    pub fn save(&self, persistence: &Persistence) -> Result<()> {
+        persistence.save_config(APP_CONFIG_FILENAME, &self)
+    }
+
+    pub fn update(&mut self, args: &CliArgs) -> bool {
+        let mut updated = false;
+        if let Some(pref) = args.wgpu_power_preference {
+            self.power_preference = pref.into();
+            updated = true;
+        }
+        if let Some(force_fallback) = args.wgpu_force_fallback {
+            self.force_fallback = force_fallback;
+            updated = true;
+        }
+        if let Some(save_data_location) = args.save_data_location {
+            self.save_data_location = save_data_location;
+            updated = true;
+        }
+        updated
+    }
+}
+
+const APP_CONFIG_FILENAME: &str = "config";
+
 const fn default_audio_enabled() -> bool {
     true
 }
@@ -75,11 +164,17 @@ pub struct SimConfig {
     pub dimensions: Vec2,
     #[serde(default = "default_audio_enabled")]
     pub audio_enabled: bool,
+    #[serde(default)]
+    pub low_battery: bool,
+    #[serde(default)]
+    pub watch_rom: bool,
+    #[serde(default)]
+    pub position: Option<Pos2>,
 }
 
 impl SimConfig {
     pub fn load(persistence: &Persistence, sim_id: SimId) -> Self {
-        if let Ok(config) = persistence.load_config(config_filename(sim_id)) {
+        if let Ok(config) = persistence.load_config(sim_config_filename(sim_id)) {
             return config;
         }
         Self {
@@ -87,15 +182,18 @@ impl SimConfig {
             colors: COLOR_PRESETS[0],
             dimensions: DisplayMode::Anaglyph.proportions() + Vec2::new(0.0, 22.0),
             audio_enabled: true,
+            low_battery: false,
+            watch_rom: false,
+            position: None,
         }
     }
 
     pub fn save(&self, persistence: &Persistence, sim_id: SimId) -> Result<()> {
-        persistence.save_config(config_filename(sim_id), self)
+        persistence.save_config(sim_config_filename(sim_id), self)
     }
 }
 
-fn config_filename(sim_id: SimId) -> &'static str {
+fn sim_config_filename(sim_id: SimId) -> &'static str {
     match sim_id {
         SimId::Player1 => "config_p1",
         SimId::Player2 => "config_p2",

src/controller.rs

@@ -1,4 +1,7 @@
-use std::sync::{Arc, RwLock};
+use std::{
+    collections::HashMap,
+    sync::{Arc, RwLock},
+};
 
 use gilrs::{Event as GamepadEvent, EventType, GamepadId, ev::Code};
 use winit::{
@@ -8,12 +11,13 @@ use winit::{
 
 use crate::{
     emulator::{EmulatorClient, EmulatorCommand, SimId, VBKey},
-    input::{InputMapping, MappingProvider},
+    input::{AxisMapping, InputMapping, MappingProvider},
 };
 
 pub struct Controller {
     pub sim_id: SimId,
     state: VBKey,
+    axis_values: HashMap<(GamepadId, Code), f32>,
     mapping: Arc<RwLock<InputMapping>>,
 }
 
@@ -22,6 +26,7 @@ impl Controller {
         Self {
             sim_id,
             state: VBKey::SGN,
+            axis_values: HashMap::new(),
             mapping: mappings.for_sim(sim_id).clone(),
         }
     }
@@ -45,20 +50,23 @@ impl Controller {
                 (VBKey::empty(), mappings)
             }
             EventType::AxisChanged(_, value, code) => {
-                let (neg, pos) = self.map_axis(&event.id, &code)?;
-                let mut pressed = VBKey::empty();
-                let mut released = VBKey::empty();
-                if value < -0.75 {
-                    pressed = pressed.union(neg);
-                }
-                if value > 0.75 {
-                    pressed = pressed.union(pos);
-                }
-                if value > -0.65 {
-                    released = released.union(neg);
-                }
-                if value < 0.65 {
-                    released = released.union(pos);
+                let mapping = self.map_axis(&event.id, &code)?;
+                self.axis_values.insert((event.id, code), value);
+
+                let pair_value = mapping
+                    .pair
+                    .and_then(|p| self.axis_values.get(&(event.id, p)))
+                    .copied()
+                    .unwrap_or_default();
+                let neg = mapping.neg;
+                let pos = mapping.pos;
+
+                let (mut pressed, mut released) = axis_presses(value, pair_value, neg, pos);
+                if let Some(other) = mapping.pair.and_then(|p| self.map_axis(&event.id, &p)) {
+                    let (other_pressed, other_released) =
+                        axis_presses(pair_value, value, other.neg, other.pos);
+                    pressed = pressed.union(other_pressed);
+                    released = released.union(other_released);
                 }
                 (pressed, released)
             }
@@ -69,6 +77,15 @@ impl Controller {
         self.update_state(pressed, released)
     }
 
+    pub fn low_battery(&mut self, pwr: bool) -> Option<VBKey> {
+        let (pressed, released) = if pwr {
+            (VBKey::PWR, VBKey::empty())
+        } else {
+            (VBKey::empty(), VBKey::PWR)
+        };
+        self.update_state(pressed, released)
+    }
+
     fn update_state(&mut self, pressed: VBKey, released: VBKey) -> Option<VBKey> {
         let old_state = self.state;
         self.state = self.state.union(pressed).difference(released);
@@ -87,7 +104,7 @@ impl Controller {
         self.mapping.read().unwrap().map_button(id, code)
     }
 
-    fn map_axis(&self, id: &GamepadId, code: &Code) -> Option<(VBKey, VBKey)> {
+    fn map_axis(&self, id: &GamepadId, code: &Code) -> Option<AxisMapping> {
         self.mapping.read().unwrap().map_axis(id, code)
     }
 }
@@ -125,4 +142,104 @@ impl ControllerManager {
             }
         }
     }
+
+    pub fn handle_low_battery(&mut self, sim_id: SimId, pwr: bool) {
+        let controller = &mut self.controllers[sim_id.to_index()];
+        if let Some(pressed) = controller.low_battery(pwr) {
+            self.client
+                .send_command(EmulatorCommand::SetKeys(controller.sim_id, pressed));
+        }
+    }
+}
+
+fn axis_presses(value: f32, pair_value: f32, neg: VBKey, pos: VBKey) -> (VBKey, VBKey) {
+    use std::f32::consts::FRAC_PI_3;
+
+    let mut pressed = VBKey::empty();
+    let mut released = VBKey::empty();
+
+    let magnitude = value.hypot(pair_value);
+    let abs_angle = pair_value.atan2(value).abs();
+
+    if magnitude < 0.65 {
+        released = released.union(neg).union(pos);
+    } else if abs_angle <= FRAC_PI_3 {
+        // stick tilted towards positive
+        released = released.union(neg);
+
+        if magnitude >= 0.75 {
+            pressed = pressed.union(pos);
+        }
+    } else if abs_angle >= 2.0 * FRAC_PI_3 {
+        // stick tilted towards negative
+        released = released.union(pos);
+
+        if magnitude >= 0.75 {
+            pressed = pressed.union(neg);
+        }
+    } else {
+        released = released.union(neg).union(pos);
+    }
+
+    (pressed, released)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{VBKey, axis_presses};
+
+    const NEG: VBKey = VBKey::LL;
+    const POS: VBKey = VBKey::LR;
+
+    const NONE: VBKey = VBKey::empty();
+    const BOTH: VBKey = NEG.union(POS);
+
+    #[test]
+    fn detects_no_input() {
+        let (pressed, released) = axis_presses(0.0, 0.0, NEG, POS);
+        assert_eq!(pressed, NONE);
+        assert_eq!(released, BOTH);
+    }
+
+    #[test]
+    fn detects_pos_input() {
+        let (pressed, released) = axis_presses(1.0, 0.0, NEG, POS);
+        assert_eq!(pressed, POS);
+        assert_eq!(released, NEG);
+    }
+
+    #[test]
+    fn detects_neg_input() {
+        let (pressed, released) = axis_presses(-1.0, 0.0, NEG, POS);
+        assert_eq!(pressed, NEG);
+        assert_eq!(released, POS);
+    }
+
+    #[test]
+    fn respects_dead_zone() {
+        let (pressed, released) = axis_presses(0.70, 0.0, NEG, POS);
+        assert_eq!(pressed, NONE);
+        assert_eq!(released, NEG);
+    }
+
+    #[test]
+    fn handles_diagonals_ok() {
+        let (pressed, released) = axis_presses(0.6, 0.6, NEG, POS);
+        assert_eq!(pressed, POS);
+        assert_eq!(released, NEG);
+    }
+
+    #[test]
+    fn ignores_diagonal_noise() {
+        let (pressed, released) = axis_presses(-1.0, -0.1484245, NEG, POS);
+        assert_eq!(pressed, NEG);
+        assert_eq!(released, POS);
+    }
+
+    #[test]
+    fn ignores_small_values() {
+        let (pressed, released) = axis_presses(-0.1484245, -1.0, NEG, POS);
+        assert_eq!(pressed, NONE);
+        assert_eq!(released, BOTH);
+    }
 }

src/emulator.rs

@@ -18,6 +18,7 @@ use tracing::{error, warn};
 
 use crate::{
     audio::Audio,
+    config::SaveDataLocation,
     graphics::TextureSink,
     memory::{MemoryRange, MemoryRegion},
 };
@@ -74,12 +75,13 @@ pub struct EmulatorBuilder {
     state: Arc<Atomic<EmulatorState>>,
     audio_on: Arc<[AtomicBool; 2]>,
     linked: Arc<AtomicBool>,
+    save_data_location: Arc<Atomic<SaveDataLocation>>,
     start_paused: bool,
     watch_rom: Arc<[AtomicBool; 2]>,
 }
 
 impl EmulatorBuilder {
-    pub fn new() -> (Self, EmulatorClient) {
+    pub fn new(save_data_location: SaveDataLocation) -> (Self, EmulatorClient) {
         let (queue, commands) = mpsc::channel();
         let builder = Self {
             rom: None,
@@ -91,6 +93,7 @@ impl EmulatorBuilder {
             state: Arc::new(Atomic::new(EmulatorState::Paused)),
             audio_on: Arc::new([AtomicBool::new(true), AtomicBool::new(true)]),
             linked: Arc::new(AtomicBool::new(false)),
+            save_data_location: Arc::new(Atomic::new(save_data_location)),
             start_paused: false,
             watch_rom: Arc::new([AtomicBool::new(false), AtomicBool::new(false)]),
         };
@@ -98,8 +101,9 @@ impl EmulatorBuilder {
             queue,
             sim_state: builder.sim_state.clone(),
             state: builder.state.clone(),
-            watch_rom: builder.watch_rom.clone(),
             linked: builder.linked.clone(),
+            save_data_location: builder.save_data_location.clone(),
+            watch_rom: builder.watch_rom.clone(),
         };
         (builder, client)
     }
@@ -131,18 +135,42 @@ impl EmulatorBuilder {
     }
 
     pub fn build(self) -> Result<Emulator> {
-        let mut emulator = Emulator::new(
-            self.commands,
-            self.sim_state,
-            self.state,
-            self.audio_on,
-            self.watch_rom,
-            self.linked,
-        )?;
-        if let Some(path) = self.rom {
+        let Self {
+            rom,
+            commands,
+            sim_state,
+            state,
+            audio_on,
+            watch_rom,
+            linked,
+            save_data_location,
+            start_paused,
+        } = self;
+        let mut emulator = Emulator {
+            sims: vec![],
+            carts: [None, None],
+            audio: Audio::init(),
+            commands,
+            sim_state,
+            state,
+            audio_on,
+            watch_rom,
+            linked,
+            save_data_location,
+            profilers: [None, None],
+            renderers: HashMap::new(),
+            messages: HashMap::new(),
+            debuggers: HashMap::new(),
+            stdouts: HashMap::new(),
+            watched_regions: HashMap::new(),
+            eye_contents: [vec![0u8; 384 * 224 * 2], vec![0u8; 384 * 224 * 2]],
+            audio_samples: Vec::with_capacity(EXPECTED_FRAME_SIZE),
+            buffer: vec![],
+        };
+        if let Some(path) = rom {
             emulator.load_cart(SimId::Player1, &path)?;
         }
-        if self.start_paused {
+        if start_paused {
             emulator.pause_sims()?;
         }
         Ok(emulator)
@@ -159,6 +187,7 @@ pub struct Emulator {
     audio_on: Arc<[AtomicBool; 2]>,
     watch_rom: Arc<[AtomicBool; 2]>,
     linked: Arc<AtomicBool>,
+    save_data_location: Arc<Atomic<SaveDataLocation>>,
     profilers: [Option<ProfileSender>; 2],
     renderers: HashMap<SimId, TextureSink>,
     messages: HashMap<SimId, mpsc::Sender<Toast>>,
@@ -171,36 +200,6 @@ pub struct Emulator {
 }
 
 impl Emulator {
-    fn new(
-        commands: mpsc::Receiver<EmulatorCommand>,
-        sim_state: Arc<[Atomic<SimState>; 2]>,
-        state: Arc<Atomic<EmulatorState>>,
-        audio_on: Arc<[AtomicBool; 2]>,
-        watch_rom: Arc<[AtomicBool; 2]>,
-        linked: Arc<AtomicBool>,
-    ) -> Result<Self> {
-        Ok(Self {
-            sims: vec![],
-            carts: [None, None],
-            audio: Audio::init()?,
-            commands,
-            sim_state,
-            state,
-            audio_on,
-            watch_rom,
-            linked,
-            profilers: [None, None],
-            renderers: HashMap::new(),
-            messages: HashMap::new(),
-            debuggers: HashMap::new(),
-            stdouts: HashMap::new(),
-            watched_regions: HashMap::new(),
-            eye_contents: [vec![0u8; 384 * 224 * 2], vec![0u8; 384 * 224 * 2]],
-            audio_samples: Vec::with_capacity(EXPECTED_FRAME_SIZE),
-            buffer: vec![],
-        })
-    }
-
     pub fn reload_cart(&mut self, sim_id: SimId) -> Result<()> {
         let Some(cart) = &self.carts[sim_id.to_index()] else {
             return Ok(());
@@ -211,7 +210,12 @@ impl Emulator {
 
     pub fn load_cart(&mut self, sim_id: SimId, path: &Path) -> Result<()> {
         let watch = self.watch_rom[sim_id.to_index()].load(Ordering::Acquire);
-        let cart = Cart::load(path, sim_id, watch)?;
+        let cart = Cart::load(
+            path,
+            sim_id,
+            self.save_data_location.load(Ordering::Acquire),
+            watch,
+        )?;
         self.try_reset_sim(sim_id, Some(cart))?;
         Ok(())
     }
@@ -224,7 +228,12 @@ impl Emulator {
         };
         let watch = self.watch_rom[SimId::Player2.to_index()].load(Ordering::Acquire);
         let cart = match file_path {
-            Some(rom_path) => Some(Cart::load(&rom_path, SimId::Player2, watch)?),
+            Some(rom_path) => Some(Cart::load(
+                &rom_path,
+                SimId::Player2,
+                self.save_data_location.load(Ordering::Acquire),
+                watch,
+            )?),
             None => None,
         };
         self.try_reset_sim(SimId::Player2, cart)?;
@@ -265,7 +274,8 @@ impl Emulator {
         } else if let Some(cart) = self.carts[index].as_mut()
             && cart.is_watching()
         {
-            cart.restart_watching();
+            cart.reload()?;
+            sim.load_cart(cart.rom.clone(), cart.sram.clone())?;
         }
         let mut profiling = false;
         if let Some(profiler) = self.profilers[sim_id.to_index()].as_ref()
@@ -686,6 +696,20 @@ impl Emulator {
                     cart.stop_watching();
                 }
             }
+            EmulatorCommand::SetSaveDataLocation(save_data_location) => {
+                self.save_data_location
+                    .store(save_data_location, Ordering::Release);
+                for sim_id in SimId::values() {
+                    if let Some(cart) = self.carts[sim_id.to_index()].as_mut()
+                        && let Err(error) = cart.change_save_data_location(save_data_location)
+                    {
+                        self.report_error(
+                            sim_id,
+                            format!("Error changing save data location: {error}"),
+                        );
+                    }
+                }
+            }
             EmulatorCommand::StartSecondSim(path) => {
                 if let Err(error) = self.start_second_sim(path) {
                     self.report_error(
@@ -853,6 +877,7 @@ pub enum EmulatorCommand {
     LoadGame(SimId, PathBuf),
     ReloadRom(SimId),
     WatchRom(SimId, bool),
+    SetSaveDataLocation(SaveDataLocation),
     StartSecondSim(Option<PathBuf>),
     StopSecondSim,
     Pause,
@@ -942,10 +967,14 @@ pub struct EmulatorClient {
     sim_state: Arc<[Atomic<SimState>; 2]>,
     state: Arc<Atomic<EmulatorState>>,
     linked: Arc<AtomicBool>,
+    save_data_location: Arc<Atomic<SaveDataLocation>>,
     watch_rom: Arc<[AtomicBool; 2]>,
 }
 
 impl EmulatorClient {
+    pub fn has_player_2(&self) -> bool {
+        self.sim_state(SimId::Player2) != SimState::Uninitialized
+    }
     pub fn sim_state(&self, sim_id: SimId) -> SimState {
         self.sim_state[sim_id.to_index()].load(Ordering::Acquire)
     }
@@ -955,6 +984,9 @@ impl EmulatorClient {
     pub fn are_sims_linked(&self) -> bool {
         self.linked.load(Ordering::Acquire)
     }
+    pub fn save_data_location(&self) -> SaveDataLocation {
+        self.save_data_location.load(Ordering::Acquire)
+    }
     pub fn is_rom_watched(&self, sim_id: SimId) -> bool {
         self.watch_rom[sim_id.to_index()].load(Ordering::Acquire)
     }

src/emulator/cart.rs

@@ -8,10 +8,15 @@ use std::{
     sync::{Arc, atomic::AtomicBool},
 };
 
-use crate::emulator::{SimId, game_info::GameInfo, shrooms_vb_util::rom_from_isx};
+use crate::{
+    config::SaveDataLocation,
+    emulator::{SimId, game_info::GameInfo, shrooms_vb_util::rom_from_isx},
+    filesystem,
+};
 
 pub struct Cart {
     pub file_path: PathBuf,
+    sim_id: SimId,
     pub rom: Vec<u8>,
     sram_file: File,
     pub sram: Vec<u8>,
@@ -21,18 +26,20 @@ pub struct Cart {
 }
 
 impl Cart {
-    pub fn load(file_path: &Path, sim_id: SimId, watch: bool) -> Result<Self> {
-        let rom = fs::read(file_path)?;
-        let (rom, info) = try_parse_isx(file_path, &rom)
-            .or_else(|| try_parse_elf(file_path, &rom))
-            .unwrap_or_else(|| (rom, GameInfo::empty(file_path)));
+    pub fn load(
+        file_path: &Path,
+        sim_id: SimId,
+        save_data_location: SaveDataLocation,
+        watch: bool,
+    ) -> Result<Self> {
+        let (rom, info) = Self::read_rom(file_path)?;
 
         let mut sram_file = File::options()
             .read(true)
             .write(true)
             .create(true)
             .truncate(false)
-            .open(sram_path(file_path, sim_id))?;
+            .open(sram_path(file_path, sim_id, save_data_location))?;
 
         let sram = if sram_file.metadata()?.len() == 0 {
             // new SRAM file, randomize the contents
@@ -57,6 +64,7 @@ impl Cart {
 
         Ok(Cart {
             file_path: file_path.to_path_buf(),
+            sim_id,
             rom,
             sram_file,
             sram,
@@ -66,6 +74,29 @@ impl Cart {
         })
     }
 
+    pub fn reload(&mut self) -> Result<()> {
+        let (rom, info) = Self::read_rom(&self.file_path)?;
+        self.rom = rom;
+        self.info = Arc::new(info);
+        if self.is_watching() {
+            self.restart_watching();
+        }
+        Ok(())
+    }
+
+    pub fn change_save_data_location(
+        &mut self,
+        save_data_location: SaveDataLocation,
+    ) -> Result<()> {
+        self.sram_file = File::options()
+            .read(true)
+            .write(true)
+            .create(true)
+            .truncate(false)
+            .open(sram_path(&self.file_path, self.sim_id, save_data_location))?;
+        self.save_sram()
+    }
+
     pub fn save_sram(&mut self) -> Result<()> {
         self.sram_file.seek(SeekFrom::Start(0))?;
         self.sram_file.write_all(&self.sram)?;
@@ -92,6 +123,14 @@ impl Cart {
         self.changed = Arc::new(AtomicBool::new(false));
         self.watcher = None;
     }
+
+    fn read_rom(file_path: &Path) -> Result<(Vec<u8>, GameInfo)> {
+        let rom = fs::read(file_path)?;
+        let (rom, info) = try_parse_isx(file_path, &rom)
+            .or_else(|| try_parse_elf(file_path, &rom))
+            .unwrap_or_else(|| (rom, GameInfo::empty(file_path)));
+        Ok((rom, info))
+    }
 }
 
 fn build_watcher(file_path: &Path, changed: Arc<AtomicBool>) -> Option<notify::RecommendedWatcher> {
@@ -162,9 +201,17 @@ fn parse_elf_program<Elf: object::read::elf::FileHeader<Endian = object::Endiann
     Some(bytes)
 }
 
-fn sram_path(file_path: &Path, sim_id: SimId) -> PathBuf {
-    match sim_id {
-        SimId::Player1 => file_path.with_extension("p1.sram"),
-        SimId::Player2 => file_path.with_extension("p2.sram"),
+fn sram_path(file_path: &Path, sim_id: SimId, save_data_location: SaveDataLocation) -> PathBuf {
+    let extension = match sim_id {
+        SimId::Player1 => "p1.sram",
+        SimId::Player2 => "p2.sram",
+    };
+    if let SaveDataLocation::DataDirectory = save_data_location
+        && let Some(data_dir) = filesystem::init_data_dir()
+        && let Some(rom_name) = file_path.file_name()
+    {
+        data_dir.join(rom_name).with_extension(extension)
+    } else {
+        file_path.with_extension(extension)
     }
 }

src/filepicker.rs

@@ -0,0 +1,103 @@
+#[cfg(target_os = "linux")]
+use std::fmt::Write as _;
+use std::{
+    path::PathBuf,
+    sync::{Arc, Weak},
+};
+
+use winit::window::Window;
+
+pub struct FilePicker {
+    window: Option<Weak<Window>>,
+}
+
+impl FilePicker {
+    pub fn new() -> Self {
+        Self { window: None }
+    }
+
+    pub fn set_window(&mut self, window: &Arc<Window>) {
+        self.window = Some(Arc::downgrade(window));
+    }
+
+    pub fn pick_file_dialog(&self) -> FileDialogBuilder {
+        self.new_dialog(FileDialogAction::PickFile, false)
+    }
+
+    pub fn save_file_dialog(&self) -> FileDialogBuilder {
+        self.new_dialog(FileDialogAction::SaveFile, cfg!(not(target_os = "windows")))
+    }
+
+    fn new_dialog(&self, action: FileDialogAction, attach_window: bool) -> FileDialogBuilder {
+        #[cfg(not(target_os = "macos"))]
+        let mut dialog = rfd::AsyncFileDialog::new();
+        #[cfg(target_os = "macos")]
+        let mut dialog = rfd::FileDialog::new();
+
+        if attach_window && let Some(window) = self.window.as_ref().and_then(|w| w.upgrade()) {
+            dialog = dialog.set_parent(&window);
+        }
+        FileDialogBuilder { dialog, action }
+    }
+}
+
+pub struct FileDialogBuilder {
+    #[cfg(not(target_os = "macos"))]
+    dialog: rfd::AsyncFileDialog,
+    #[cfg(target_os = "macos")]
+    dialog: rfd::FileDialog,
+    action: FileDialogAction,
+}
+
+impl FileDialogBuilder {
+    pub fn add_filter(self, name: impl Into<String>, extensions: &[impl ToString]) -> Self {
+        #[cfg(target_os = "linux")]
+        let exts = extensions
+            .iter()
+            .map(|ext| {
+                let mut normalized = String::new();
+                for char in ext.to_string().chars() {
+                    if char.is_ascii_lowercase() {
+                        let _ = write!(&mut normalized, "[{char}{}]", char.to_ascii_uppercase());
+                    } else {
+                        normalized.push(char);
+                    }
+                }
+                normalized
+            })
+            .collect::<Vec<_>>();
+        #[cfg(target_os = "linux")]
+        let extensions = &exts;
+        Self {
+            dialog: self.dialog.add_filter(name, extensions),
+            ..self
+        }
+    }
+
+    pub fn set_file_name(self, file_name: impl Into<String>) -> Self {
+        Self {
+            dialog: self.dialog.set_file_name(file_name),
+            ..self
+        }
+    }
+
+    pub fn open(self) -> Option<PathBuf> {
+        #[cfg(not(target_os = "macos"))]
+        fn resolve(action: impl Future<Output = Option<rfd::FileHandle>>) -> Option<PathBuf> {
+            pollster::block_on(action).map(Into::into)
+        }
+        #[cfg(target_os = "macos")]
+        fn resolve(action: Option<PathBuf>) -> Option<PathBuf> {
+            action
+        }
+        match self.action {
+            FileDialogAction::PickFile => resolve(self.dialog.pick_file()),
+            FileDialogAction::SaveFile => resolve(self.dialog.save_file()),
+        }
+    }
+}
+
+enum FileDialogAction {
+    PickFile,
+    SaveFile,
+}

src/filesystem.rs

@@ -0,0 +1,52 @@
+use std::{fs, path::PathBuf};
+
+use anyhow::{Result, bail};
+use directories::ProjectDirs;
+use serde::{Deserialize, Serialize};
+
+#[derive(Clone)]
+pub struct Persistence {
+    config_dir: Option<PathBuf>,
+}
+
+impl Persistence {
+    pub fn new() -> Self {
+        Self {
+            config_dir: init_config_dir(),
+        }
+    }
+
+    pub fn save_config<T: Serialize>(&self, file: &str, data: &T) -> Result<()> {
+        if let Some(config_dir) = self.config_dir.as_ref() {
+            let bytes = serde_json::to_vec_pretty(data)?;
+            let filename = config_dir.join(file).with_extension("json");
+            fs::write(&filename, bytes)?;
+        }
+        Ok(())
+    }
+
+    pub fn load_config<T: for<'a> Deserialize<'a>>(&self, file: &str) -> Result<T> {
+        let Some(config_dir) = self.config_dir.as_ref() else {
+            bail!("config directory not found");
+        };
+        let filename = config_dir.join(file).with_extension("json");
+        let bytes = fs::read(filename)?;
+        Ok(serde_json::from_slice(&bytes)?)
+    }
+}
+
+fn init_config_dir() -> Option<PathBuf> {
+    let config_dir = project_dirs()?.config_dir().to_path_buf();
+    fs::create_dir_all(&config_dir).ok()?;
+    Some(config_dir)
+}
+
+pub fn init_data_dir() -> Option<PathBuf> {
+    let data_dir = project_dirs()?.data_dir().to_path_buf();
+    fs::create_dir_all(&data_dir).ok()?;
+    Some(data_dir)
+}
+
+fn project_dirs() -> Option<ProjectDirs> {
+    ProjectDirs::from("com", "virtual-boy", "Lemur")
+}

src/input.rs

@@ -14,7 +14,7 @@ use winit::keyboard::{KeyCode, PhysicalKey};
 
 use crate::{
     emulator::{SimId, VBKey},
-    persistence::Persistence,
+    filesystem::Persistence,
 };
 
 #[derive(Clone, PartialEq, Eq, Hash)]
@@ -52,12 +52,28 @@ pub trait Mappings {
     fn use_default_mappings(&mut self);
 }
 
+#[derive(Clone, Copy, Serialize, Deserialize)]
+pub struct AxisMapping {
+    pub neg: VBKey,
+    pub pos: VBKey,
+    pub pair: Option<Code>,
+}
+impl Default for AxisMapping {
+    fn default() -> Self {
+        Self {
+            neg: VBKey::empty(),
+            pos: VBKey::empty(),
+            pair: None,
+        }
+    }
+}
+
 #[derive(Serialize, Deserialize)]
 pub struct GamepadMapping {
     buttons: HashMap<Code, VBKey>,
-    axes: HashMap<Code, (VBKey, VBKey)>,
+    axes: HashMap<Code, AxisMapping>,
     default_buttons: HashMap<Code, VBKey>,
-    default_axes: HashMap<Code, (VBKey, VBKey)>,
+    default_axes: HashMap<Code, AxisMapping>,
 }
 
 impl GamepadMapping {
@@ -78,7 +94,8 @@ impl GamepadMapping {
         let mut default_axes = HashMap::new();
         let mut default_axis = |axis: Axis, neg: VBKey, pos: VBKey| {
             if let Some(code) = gamepad.axis_code(axis) {
-                default_axes.insert(code, (neg, pos));
+                let pair = axis.second_axis().and_then(|a| gamepad.axis_code(a));
+                default_axes.insert(code, AxisMapping { neg, pos, pair });
             }
         };
         default_axis(Axis::LeftStickX, VBKey::LL, VBKey::LR);
@@ -102,19 +119,13 @@ impl GamepadMapping {
     }
 
     pub fn add_axis_neg_mapping(&mut self, key: VBKey, code: Code) {
-        let entry = self
-            .axes
-            .entry(code)
-            .or_insert((VBKey::empty(), VBKey::empty()));
-        entry.0 = entry.0.union(key);
+        let entry = self.axes.entry(code).or_default();
+        entry.neg = entry.neg.union(key);
     }
 
     pub fn add_axis_pos_mapping(&mut self, key: VBKey, code: Code) {
-        let entry = self
-            .axes
-            .entry(code)
-            .or_insert((VBKey::empty(), VBKey::empty()));
-        entry.1 = entry.1.union(key);
+        let entry = self.axes.entry(code).or_default();
+        entry.pos = entry.pos.union(key);
     }
 
     fn save_mappings(&self) -> PersistedGamepadMapping {
@@ -145,11 +156,11 @@ impl GamepadMapping {
 impl Mappings for GamepadMapping {
     fn mapping_names(&self) -> HashMap<VBKey, Vec<String>> {
         let mut results: HashMap<VBKey, Vec<String>> = HashMap::new();
-        for (axis, (left_keys, right_keys)) in &self.axes {
-            for key in left_keys.iter() {
+        for (axis, mapping) in &self.axes {
+            for key in mapping.neg.iter() {
                 results.entry(key).or_default().push(format!("-{axis}"));
             }
-            for key in right_keys.iter() {
+            for key in mapping.pos.iter() {
                 results.entry(key).or_default().push(format!("+{axis}"));
             }
         }
@@ -162,10 +173,10 @@ impl Mappings for GamepadMapping {
     }
 
     fn clear_mappings(&mut self, key: VBKey) {
-        self.axes.retain(|_, (left, right)| {
-            *left = left.difference(key);
-            *right = right.difference(key);
-            !(left.is_empty() && right.is_empty())
+        self.axes.retain(|_, mapping| {
+            mapping.neg = mapping.neg.difference(key);
+            mapping.pos = mapping.pos.difference(key);
+            !(mapping.neg.is_empty() && mapping.pos.is_empty())
         });
         self.buttons.retain(|_, keys| {
             *keys = keys.difference(key);
@@ -200,7 +211,7 @@ impl InputMapping {
         mappings.buttons.get(code).copied()
     }
 
-    pub fn map_axis(&self, id: &GamepadId, code: &Code) -> Option<(VBKey, VBKey)> {
+    pub fn map_axis(&self, id: &GamepadId, code: &Code) -> Option<AxisMapping> {
         let mappings = self.gamepads.get(id)?.read().unwrap();
         mappings.axes.get(code).copied()
     }
@@ -459,9 +470,9 @@ struct PersistedKeyboardMapping {
 #[derive(Serialize, Deserialize)]
 struct PersistedGamepadMapping {
     buttons: Vec<(Code, VBKey)>,
-    axes: Vec<(Code, (VBKey, VBKey))>,
+    axes: Vec<(Code, AxisMapping)>,
     default_buttons: Vec<(Code, VBKey)>,
-    default_axes: Vec<(Code, (VBKey, VBKey))>,
+    default_axes: Vec<(Code, AxisMapping)>,
 }
 
 #[derive(Clone, Copy, Serialize, Deserialize, PartialEq, Eq, Hash)]

src/main.rs

@@ -13,9 +13,9 @@ use tracing_subscriber::{EnvFilter, Layer, layer::SubscriberExt, util::Subscribe
 use winit::event_loop::{ControlFlow, EventLoop};
 
 use crate::{
-    config::{CliArgs, SimConfig},
+    config::{AppConfig, CliArgs, SimConfig},
     emulator::SimId,
-    persistence::Persistence,
+    filesystem::Persistence,
 };
 
 mod app;
@@ -23,12 +23,13 @@ mod audio;
 mod config;
 mod controller;
 mod emulator;
+mod filepicker;
+mod filesystem;
 mod gdbserver;
 mod graphics;
 mod images;
 mod input;
 mod memory;
-mod persistence;
 mod profiler;
 mod window;
 
@@ -59,14 +60,9 @@ fn set_panic_handler() {
 
         eprint!("{message}");
 
-        let Some(project_dirs) = directories::ProjectDirs::from("com", "virtual-boy", "Lemur")
-        else {
+        let Some(data_dir) = filesystem::init_data_dir() else {
             return;
         };
-        let data_dir = project_dirs.data_dir();
-        if std::fs::create_dir_all(data_dir).is_err() {
-            return;
-        }
         let timestamp = SystemTime::now()
             .duration_since(SystemTime::UNIX_EPOCH)
             .unwrap()
@@ -97,7 +93,14 @@ fn main() -> Result<()> {
 
     let persistence = Persistence::new();
 
-    let (mut builder, client) = EmulatorBuilder::new();
+    let mut config = AppConfig::load(&persistence);
+    if config.update(&args) {
+        let _ = config.save(&persistence);
+    }
+    let p1 = SimConfig::load(&persistence, SimId::Player1);
+    let p2 = SimConfig::load(&persistence, SimId::Player2);
+
+    let (mut builder, client) = EmulatorBuilder::new(config.save_data_location);
     if let Some(path) = &args.rom {
         builder = builder.with_rom(path);
     }
@@ -110,8 +113,6 @@ fn main() -> Result<()> {
     if args.profile {
         builder = builder.start_paused(true)
     }
-    let p1 = SimConfig::load(&persistence, SimId::Player1);
-    let p2 = SimConfig::load(&persistence, SimId::Player2);
 
     let watch = args.watch;
 
@@ -136,6 +137,14 @@ fn main() -> Result<()> {
     let event_loop = EventLoop::with_user_event().build().unwrap();
     event_loop.set_control_flow(ControlFlow::Poll);
     let proxy = event_loop.create_proxy();
-    event_loop.run_app(&mut Application::new(client, proxy, persistence, args))?;
+    let handle = event_loop.owned_display_handle();
+    event_loop.run_app(&mut Application::new(
+        client,
+        proxy,
+        handle,
+        persistence,
+        args,
+        config,
+    ))?;
     Ok(())
 }

src/persistence.rs

@@ -1,46 +0,0 @@
-use std::{fs, path::PathBuf};
-
-use anyhow::{Result, bail};
-use directories::ProjectDirs;
-use serde::{Deserialize, Serialize};
-
-#[derive(Clone)]
-pub struct Persistence {
-    dirs: Option<Dirs>,
-}
-
-impl Persistence {
-    pub fn new() -> Self {
-        Self { dirs: init_dirs() }
-    }
-
-    pub fn save_config<T: Serialize>(&self, file: &str, data: &T) -> Result<()> {
-        if let Some(dirs) = self.dirs.as_ref() {
-            let bytes = serde_json::to_vec_pretty(data)?;
-            let filename = dirs.config_dir.join(file).with_extension("json");
-            fs::write(&filename, bytes)?;
-        }
-        Ok(())
-    }
-
-    pub fn load_config<T: for<'a> Deserialize<'a>>(&self, file: &str) -> Result<T> {
-        let Some(dirs) = self.dirs.as_ref() else {
-            bail!("config directory not found");
-        };
-        let filename = dirs.config_dir.join(file).with_extension("json");
-        let bytes = fs::read(filename)?;
-        Ok(serde_json::from_slice(&bytes)?)
-    }
-}
-
-#[derive(Clone)]
-struct Dirs {
-    config_dir: PathBuf,
-}
-
-fn init_dirs() -> Option<Dirs> {
-    let dirs = ProjectDirs::from("com", "virtual-boy", "Lemur")?;
-    let config_dir = dirs.config_dir().to_path_buf();
-    fs::create_dir_all(&config_dir).ok()?;
-    Some(Dirs { config_dir })
-}

src/window.rs

@@ -1,4 +1,4 @@
-use std::sync::Arc;
+use std::{path::PathBuf, sync::Arc};
 
 pub use about::AboutWindow;
 use egui::{Ui, ViewportBuilder};
@@ -28,11 +28,11 @@ mod utils;
 mod vip;
 
 pub trait AppWindow {
-    fn sim_id(&self) -> SimId {
-        SimId::Player1
+    fn sim_id(&self) -> Option<SimId> {
+        None
     }
     fn image_url(&self, name: &str) -> String {
-        format!("vip://{}/{name}", self.sim_id())
+        format!("vip://{}/{name}", self.sim_id().unwrap_or(SimId::Player1))
     }
     fn initial_viewport(&self) -> ViewportBuilder;
     fn show(&mut self, ui: &mut Ui);
@@ -47,6 +47,10 @@ pub trait AppWindow {
         let _ = event;
         false
     }
+    fn handle_dropped_file(&mut self, path: PathBuf) -> bool {
+        let _ = path;
+        false
+    }
 }
 
 pub struct InitArgs<'a> {

src/window/about.rs

@@ -12,7 +12,7 @@ impl AppWindow for AboutWindow {
     }
 
     fn show(&mut self, ui: &mut Ui) {
-        CentralPanel::default().show_inside(ui, |ui| {
+        CentralPanel::default().show(ui, |ui| {
             ui.vertical_centered(|ui| {
                 ui.label("Lemur Virtual Boy Emulator");
                 ui.label(format!("Version {}", env!("CARGO_PKG_VERSION")));

src/window/game.rs

@@ -1,17 +1,19 @@
 use std::{
     ops::{Deref, DerefMut},
+    path::PathBuf,
     sync::{Arc, Mutex, atomic::AtomicBool, mpsc},
     time::Duration,
 };
 
 use crate::{
     app::UserEvent,
-    config::{COLOR_PRESETS, SimConfig},
+    config::{AppConfig, COLOR_PRESETS, SaveDataLocation, SimConfig},
     emulator::{EmulatorClient, EmulatorCommand, EmulatorState, SimId, SimState},
+    filepicker::FilePicker,
+    filesystem::Persistence,
     images::ImageTextureLoader,
     input::{Command, MappingProvider, ShortcutProvider},
     memory::MemoryClient,
-    persistence::Persistence,
     window::{
         AboutWindow, BgMapWindow, CharacterDataWindow, FrameBufferWindow, GdbServerWindow,
         HotkeysWindow, InitArgs, InputWindow, ObjectWindow, ProfileWindow, RegisterWindow,
@@ -20,10 +22,11 @@ use crate::{
 };
 use anyhow::Context as _;
 use egui::{
-    Align2, Button, CentralPanel, Color32, Context, Frame, MenuBar, Panel, Ui, Vec2,
+    Align2, Button, CentralPanel, Color32, Context, Frame, MenuBar, Panel, Pos2, Ui, Vec2,
     ViewportBuilder, ViewportCommand, ViewportId, ViewportIdMap, Window,
 };
 use egui_notify::{Anchor, Toast, Toasts};
+use serde::{Deserialize, Serialize};
 use winit::{event::KeyEvent, event_loop::EventLoopProxy};
 
 use super::{
@@ -45,13 +48,14 @@ pub struct GameWindow {
     messages: mpsc::Receiver<Toast>,
     message_sink: mpsc::Sender<Toast>,
     color_picker: Option<ColorPickerState>,
-    window: Option<Arc<winit::window::Window>>,
+    file_picker: FilePicker,
     memory: Arc<MemoryClient>,
     images: Arc<ImageTextureLoader>,
     mappings: MappingProvider,
     children: ViewportIdMap<ChildWindowWrapper>,
-    child_sizes: UiData<ViewportIdMap<Vec2>>,
+    child_states: UiData<ViewportIdMap<ChildState>>,
     queued_children: Vec<ChildWindow>,
+    show_player_name: bool,
 }
 
 impl GameWindow {
@@ -68,6 +72,8 @@ impl GameWindow {
         sim_id: SimId,
     ) -> Self {
         let config = SimConfig::load(&persistence, sim_id);
+        let _ = proxy.send_event(UserEvent::LowBattery(sim_id, config.low_battery));
+        client.send_command(EmulatorCommand::WatchRom(sim_id, config.watch_rom));
         let toasts = Toasts::new()
             .with_anchor(Anchor::BottomLeft)
             .with_margin((10.0, 10.0).into())
@@ -86,13 +92,14 @@ impl GameWindow {
             messages,
             message_sink,
             color_picker: None,
-            window: None,
+            file_picker: FilePicker::new(),
             memory: memory.clone(),
             images: images.clone(),
             mappings: mappings.clone(),
             children: ViewportIdMap::default(),
-            child_sizes: UiData::new(),
+            child_states: UiData::new(),
             queued_children: vec![],
+            show_player_name: false,
         }
     }
 
@@ -175,13 +182,23 @@ impl GameWindow {
         };
 
         let mut viewport = child.initial_viewport();
-        if let Some(size) = self.child_sizes.get(&viewport_id) {
-            viewport.inner_size = Some(*size);
+        let title = viewport.title.clone().unwrap();
+        let sim_id = child.sim_id();
+        if let Some(sim_id) = sim_id
+            && self.show_player_name
+        {
+            viewport.title = Some(format!("{title} ({sim_id})"));
+        }
+        if let Some(state) = self.child_states.get(&viewport_id) {
+            viewport.position = Some(state.position);
+            viewport.inner_size = Some(state.size);
         }
         self.children.insert(
             viewport_id,
             ChildWindowWrapper {
                 app: Arc::new(Mutex::new(child)),
+                title,
+                sim_id,
                 updates: Some(viewport),
                 close_requested: Arc::new(AtomicBool::new(false)),
             },
@@ -200,6 +217,10 @@ impl GameWindow {
         self.handle_event(viewport_id, |window| window.handle_gamepad_event(event))
     }
 
+    pub fn handle_dropped_file(&mut self, viewport_id: ViewportId, path: PathBuf) -> bool {
+        self.handle_event(viewport_id, |window| window.handle_dropped_file(path))
+    }
+
     fn handle_event<F, R>(&mut self, viewport_id: ViewportId, cb: F) -> R
     where
         F: FnOnce(&mut dyn AppWindow) -> R,
@@ -236,9 +257,11 @@ impl GameWindow {
         for command in ui.input_mut(|input| self.shortcuts.consume_all(input)) {
             match command {
                 Command::OpenRom => {
-                    let rom = rfd::FileDialog::new()
+                    let rom = self
+                        .file_picker
+                        .pick_file_dialog()
                         .add_filter("Virtual Boy ROMs", &["vb", "vbrom", "elf", "isx"])
-                        .pick_file();
+                        .open();
                     if let Some(path) = rom {
                         self.client
                             .send_command(EmulatorCommand::LoadGame(self.sim_id, path));
@@ -292,9 +315,11 @@ impl GameWindow {
                 .add(self.button_for(ui.ctx(), "Open ROM", Command::OpenRom))
                 .clicked()
             {
-                let rom = rfd::FileDialog::new()
+                let rom = self
+                    .file_picker
+                    .pick_file_dialog()
                     .add_filter("Virtual Boy ROMs", &["vb", "vbrom", "elf", "isx"])
-                    .pick_file();
+                    .open();
                 if let Some(path) = rom {
                     self.client
                         .send_command(EmulatorCommand::LoadGame(self.sim_id, path));
@@ -309,6 +334,7 @@ impl GameWindow {
             }
             let watch_rom = self.client.is_rom_watched(self.sim_id);
             if ui.selectable_button(watch_rom, "Watch ROM").clicked() {
+                self.update_config(|c| c.watch_rom = !watch_rom);
                 self.client
                     .send_command(EmulatorCommand::WatchRom(self.sim_id, !watch_rom));
             }
@@ -366,10 +392,18 @@ impl GameWindow {
             {
                 pollster::block_on(self.take_screenshot());
             }
+            ui.separator();
+            let low_battery = self.config.low_battery;
+            if ui.selectable_button(low_battery, "Low Battery").clicked() {
+                self.update_config(|c| c.low_battery = !low_battery);
+                let _ = self
+                    .proxy
+                    .send_event(UserEvent::LowBattery(self.sim_id, !low_battery));
+            }
         });
         ui.menu_button("Options", |ui| self.show_options_menu(ui));
         ui.menu_button("Multiplayer", |ui| {
-            let has_player_2 = self.client.sim_state(SimId::Player2) != SimState::Uninitialized;
+            let has_player_2 = self.client.has_player_2();
             if self.sim_id == SimId::Player1
                 && !has_player_2
                 && ui.button("Open Player 2").clicked()
@@ -446,13 +480,12 @@ impl GameWindow {
         self.client
             .send_command(EmulatorCommand::Screenshot(self.sim_id, tx));
         let bytes = rx.await.context("Could not take screenshot")?;
-        let mut file_dialog = rfd::FileDialog::new()
+        let file = self
+            .file_picker
+            .save_file_dialog()
             .add_filter("PNG images", &["png"])
-            .set_file_name("screenshot.png");
-        if let Some(window) = self.window.as_ref() {
-            file_dialog = file_dialog.set_parent(window);
-        }
-        let file = file_dialog.save_file();
+            .set_file_name("screenshot.png")
+            .open();
         let Some(path) = file else {
             return Ok(None);
         };
@@ -571,6 +604,37 @@ impl GameWindow {
         if ui.button("Hotkeys").clicked() {
             self.open(ChildWindow::Hotkeys);
         }
+        ui.menu_button("Save Data Location", |ui| {
+            let save_data_location = self.client.save_data_location();
+            let update_save_data_location = |new_location: SaveDataLocation| {
+                if new_location == save_data_location {
+                    return;
+                };
+                let mut app_config = AppConfig::load(&self.persistence);
+                app_config.save_data_location = new_location;
+                let _ = app_config.save(&self.persistence);
+                self.client
+                    .send_command(EmulatorCommand::SetSaveDataLocation(new_location));
+            };
+            if ui
+                .selectable_button(
+                    save_data_location == SaveDataLocation::RomDirectory,
+                    "Same Directory as ROM",
+                )
+                .clicked()
+            {
+                update_save_data_location(SaveDataLocation::RomDirectory);
+            }
+            if ui
+                .selectable_button(
+                    save_data_location == SaveDataLocation::DataDirectory,
+                    "App Data Directory",
+                )
+                .clicked()
+            {
+                update_save_data_location(SaveDataLocation::DataDirectory);
+            }
+        });
     }
 
     fn show_color_picker(&mut self, ui: &mut Ui) {
@@ -621,30 +685,61 @@ impl GameWindow {
 }
 
 impl AppWindow for GameWindow {
-    fn sim_id(&self) -> SimId {
-        self.sim_id
+    fn sim_id(&self) -> Option<SimId> {
+        Some(self.sim_id)
     }
 
     fn initial_viewport(&self) -> ViewportBuilder {
-        ViewportBuilder::default()
+        let builder = ViewportBuilder::default()
             .with_title("Lemur")
-            .with_inner_size(self.config.dimensions)
+            .with_inner_size(self.config.dimensions);
+        if let Some(position) = self.config.position {
+            builder.with_position(position)
+        } else {
+            builder
+        }
     }
 
     fn show(&mut self, ui: &mut Ui) {
-        self.child_sizes.load(ui);
+        let has_player_2 = self.client.has_player_2();
+        if !self.show_player_name && has_player_2 {
+            ui.send_viewport_cmd(ViewportCommand::Title(format!("Lemur ({})", self.sim_id)));
+            for (viewport_id, child) in &self.children {
+                if let Some(sim_id) = child.sim_id {
+                    ui.send_viewport_cmd_to(
+                        *viewport_id,
+                        ViewportCommand::Title(format!("{} ({sim_id})", child.title)),
+                    );
+                }
+            }
+            self.show_player_name = true;
+        } else if self.show_player_name && !has_player_2 {
+            ui.send_viewport_cmd(ViewportCommand::Title("Lemur".to_string()));
+            for (viewport_id, child) in &self.children {
+                if child.sim_id.is_some() {
+                    ui.send_viewport_cmd_to(
+                        *viewport_id,
+                        ViewportCommand::Title(child.title.clone()),
+                    );
+                }
+            }
+            self.show_player_name = false;
+        }
+        self.child_states.load(ui);
         let dimensions = {
             let bounds = ui.content_rect();
             bounds.max - bounds.min
         };
-        self.update_config(|c| c.dimensions = dimensions);
+        let position = ui.input(|i| i.viewport().outer_rect.map(|r| r.min));
+        self.update_config(|c| {
+            c.dimensions = dimensions;
+            c.position = position;
+        });
 
         while let Ok(toast) = self.messages.try_recv() {
             self.toasts.add(toast);
         }
-        Panel::top("menubar")
-            .exact_size(22.0)
-            .show_inside(ui, |ui| {
+        Panel::top("menubar").exact_size(22.0).show(ui, |ui| {
             MenuBar::new().ui(ui, |ui| {
                 self.show_menu(ui);
             });
@@ -659,7 +754,7 @@ impl AppWindow for GameWindow {
                 });
         }
         let frame = Frame::central_panel(ui.style()).fill(Color32::BLACK);
-        CentralPanel::default().frame(frame).show_inside(ui, |ui| {
+        CentralPanel::default().frame(frame).show(ui, |ui| {
             if let Some(screen) = self.screen.as_mut() {
                 screen.update(self.config.display_mode, self.config.colors);
                 ui.add(screen);
@@ -679,8 +774,18 @@ impl AppWindow for GameWindow {
             let app = child.app.clone();
             let viewport_builder = child.updates.take().unwrap_or_default();
             let close_requested = child.close_requested.clone();
-            let size = ui.input_for(*id, |v| v.viewport_rect().size());
-            self.child_sizes.insert(*id, size);
+            if let (Some(outer), Some(inner)) = ui.input_for(*id, |inp| {
+                let viewport = inp.viewport();
+                (viewport.outer_rect, viewport.inner_rect)
+            }) {
+                self.child_states.insert(
+                    *id,
+                    ChildState {
+                        position: outer.min,
+                        size: inner.size(),
+                    },
+                );
+            }
             ui.show_viewport_deferred(*id, viewport_builder, move |ui, _| {
                 app.lock().unwrap().show(ui);
                 if ui.input(|s| s.viewport().close_requested()) {
@@ -689,7 +794,7 @@ impl AppWindow for GameWindow {
             });
             true
         });
-        self.child_sizes.save(ui);
+        self.child_states.save(ui);
         ui.request_repaint_after(Duration::from_millis(10));
     }
 
@@ -703,7 +808,13 @@ impl AppWindow for GameWindow {
             ));
             self.screen = Some(screen);
         }
-        self.window = Some(args.window.clone());
+        self.file_picker.set_window(args.window);
+    }
+
+    fn handle_dropped_file(&mut self, path: PathBuf) -> bool {
+        self.client
+            .send_command(EmulatorCommand::LoadGame(self.sim_id, path));
+        true
     }
 }
 
@@ -724,6 +835,8 @@ struct ColorPickerState {
 
 struct ChildWindowWrapper {
     app: Arc<Mutex<AppWrapper>>,
+    title: String,
+    sim_id: Option<SimId>,
     updates: Option<ViewportBuilder>,
     close_requested: Arc<AtomicBool>,
 }
@@ -795,3 +908,9 @@ impl ChildWindow {
         }
     }
 }
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+struct ChildState {
+    position: Pos2,
+    size: Vec2,
+}

src/window/gdb.rs

@@ -42,20 +42,20 @@ impl GdbServerWindow {
 }
 
 impl AppWindow for GdbServerWindow {
-    fn sim_id(&self) -> SimId {
-        self.sim_id
+    fn sim_id(&self) -> Option<SimId> {
+        Some(self.sim_id)
     }
 
     fn initial_viewport(&self) -> ViewportBuilder {
         ViewportBuilder::default()
-            .with_title(format!("GDB Server ({})", self.sim_id))
+            .with_title("GDB Server")
             .with_inner_size((300.0, 200.0))
     }
 
     fn show(&mut self, ui: &mut egui::Ui) {
         let port_num: Option<u16> = self.port_str.parse().ok();
         let status = self.server.status();
-        CentralPanel::default().show_inside(ui, |ui| {
+        CentralPanel::default().show(ui, |ui| {
             ui.horizontal(|ui| {
                 if port_num.is_none() {
                     let style = ui.style_mut();

src/window/hotkeys.rs

@@ -131,7 +131,7 @@ impl AppWindow for HotkeysWindow {
     }
 
     fn show(&mut self, ui: &mut Ui) {
-        CentralPanel::default().show_inside(ui, |ui| {
+        CentralPanel::default().show(ui, |ui| {
             ui.horizontal(|ui| {
                 if ui.button("Use defaults").clicked() {
                     self.shortcuts.reset();

src/window/input.rs

@@ -70,7 +70,7 @@ impl InputWindow {
             .column(Column::remainder())
             .cell_layout(Layout::left_to_right(egui::Align::Center))
             .body(|mut body| {
-                for keys in KEY_NAMES.chunks_exact(2) {
+                for keys in KEY_NAMES.as_chunks::<2>().0 {
                     body.row(20.0, |mut row| {
                         for (key, name) in keys {
                             let binding = names.remove(key).map(|mut s| {
@@ -167,7 +167,7 @@ impl AppWindow for InputWindow {
     }
 
     fn show(&mut self, ui: &mut Ui) {
-        Panel::top("options").show_inside(ui, |ui| {
+        Panel::top("options").show(ui, |ui| {
             ui.horizontal(|ui| {
                 let old_active_tab = self.active_tab;
                 ui.selectable_value(&mut self.active_tab, InputTab::Player1, "Player 1");
@@ -182,7 +182,7 @@ impl AppWindow for InputWindow {
                 }
             });
         });
-        CentralPanel::default().show_inside(ui, |ui| {
+        CentralPanel::default().show(ui, |ui| {
             match self.active_tab {
                 InputTab::Player1 => self.show_key_bindings(ui, SimId::Player1),
                 InputTab::Player2 => self.show_key_bindings(ui, SimId::Player2),

src/window/profile.rs

@@ -1,12 +1,12 @@
-use std::{fs, sync::Arc, time::Duration};
+use std::{fs, time::Duration};
 
 use anyhow::Result;
 use egui::{Button, CentralPanel, Checkbox, Label, ViewportBuilder};
 use egui_notify::{Anchor, Toast, Toasts};
-use winit::window::Window;
 
 use crate::{
     emulator::{EmulatorClient, EmulatorCommand, EmulatorState, SimId},
+    filepicker::FilePicker,
     profiler::{Profiler, ProfilerStatus},
     window::{AppWindow, InitArgs},
 };
@@ -16,7 +16,7 @@ pub struct ProfileWindow {
     client: EmulatorClient,
     profiler: Profiler,
     toasts: Toasts,
-    window: Option<Arc<Window>>,
+    file_picker: FilePicker,
 }
 
 impl ProfileWindow {
@@ -29,7 +29,7 @@ impl ProfileWindow {
                 .with_anchor(Anchor::BottomLeft)
                 .with_margin((10.0, 10.0).into())
                 .reverse(true),
-            window: None,
+            file_picker: FilePicker::new(),
         }
     }
 
@@ -62,13 +62,12 @@ impl ProfileWindow {
 
     fn try_finish_recording(&mut self) -> Result<Option<String>> {
         let bytes_receiver = self.profiler.finish_recording();
-        let mut file_dialog = rfd::FileDialog::new()
+        let file = self
+            .file_picker
+            .save_file_dialog()
             .add_filter("Profiler files", &["json"])
-            .set_file_name("profile.json");
-        if let Some(window) = self.window.as_ref() {
-            file_dialog = file_dialog.set_parent(window);
-        }
-        let file = file_dialog.save_file();
+            .set_file_name("profile.json")
+            .open();
         if let Some(path) = file {
             let bytes = pollster::block_on(bytes_receiver)?;
             let _ = fs::remove_file(&path);
@@ -82,20 +81,20 @@ impl ProfileWindow {
 }
 
 impl AppWindow for ProfileWindow {
-    fn sim_id(&self) -> SimId {
-        self.sim_id
+    fn sim_id(&self) -> Option<SimId> {
+        Some(self.sim_id)
     }
 
     fn initial_viewport(&self) -> ViewportBuilder {
         ViewportBuilder::default()
-            .with_title(format!("Profiler ({})", self.sim_id))
+            .with_title("Profiler")
             .with_inner_size((300.0, 200.0))
     }
 
     fn show(&mut self, ui: &mut egui::Ui) {
         let status = self.profiler.status();
         let recording = matches!(status, ProfilerStatus::Recording);
-        CentralPanel::default().show_inside(ui, |ui| {
+        CentralPanel::default().show(ui, |ui| {
             ui.horizontal_wrapped(|ui| {
                 ui.spacing_mut().item_spacing.x = 0.0;
                 ui.add(
@@ -164,6 +163,6 @@ impl AppWindow for ProfileWindow {
     }
 
     fn on_init(&mut self, args: InitArgs) {
-        self.window = Some(args.window.clone());
+        self.file_picker.set_window(args.window);
     }
 }

src/window/terminal.rs

@@ -29,13 +29,13 @@ impl TerminalWindow {
 }
 
 impl AppWindow for TerminalWindow {
-    fn sim_id(&self) -> SimId {
-        self.sim_id
+    fn sim_id(&self) -> Option<SimId> {
+        Some(self.sim_id)
     }
 
     fn initial_viewport(&self) -> ViewportBuilder {
         ViewportBuilder::default()
-            .with_title(format!("Terminal ({})", self.sim_id))
+            .with_title("Terminal")
             .with_inner_size((640.0, 480.0))
     }
 
@@ -54,7 +54,7 @@ impl AppWindow for TerminalWindow {
             }
             self.lines.back_mut().unwrap().push_str(rest);
         }
-        CentralPanel::default().show_inside(ui, |ui| {
+        CentralPanel::default().show(ui, |ui| {
             ScrollArea::vertical()
                 .stick_to_bottom(true)
                 .auto_shrink([false, false])

src/window/utils.rs

@@ -1,6 +1,6 @@
 use std::{
     fmt::{Display, UpperHex},
-    ops::{Bound, Deref, DerefMut, RangeBounds},
+    ops::{AddAssign, Bound, Deref, DerefMut, MulAssign, RangeBounds},
     str::FromStr,
 };
 
@@ -10,7 +10,7 @@ use egui::{
     RichText, Sense, Shape, Stroke, StrokeKind, TextEdit, Ui, UiBuilder, Vec2, Widget, WidgetText,
     ecolor::HexColor, util::id_type_map::SerializableAny,
 };
-use num_traits::{CheckedAdd, CheckedSub, One};
+use num_traits::{CheckedAdd, CheckedSub, One, Zero};
 
 pub trait UiExt {
     fn section(&mut self, title: impl Into<String>, add_contents: impl FnOnce(&mut Ui));
@@ -105,14 +105,16 @@ enum Direction {
 
 pub trait Number:
     Copy
+    + Zero
     + One
+    + AddAssign
+    + MulAssign
     + CheckedAdd
     + CheckedSub
     + Eq
     + Ord
     + Display
     + FromStr
-    + FromRadix16
     + UpperHex
     + Send
     + Sync
@@ -121,14 +123,16 @@ pub trait Number:
 }
 impl<
     T: Copy
+        + Zero
         + One
+        + AddAssign
+        + MulAssign
         + CheckedAdd
         + CheckedSub
         + Eq
         + Ord
         + Display
         + FromStr
-        + FromRadix16
         + UpperHex
         + Send
         + Sync
@@ -209,8 +213,8 @@ impl<T: Number> Widget for NumberEdit<'_, T> {
         let from_string = |val: &str| {
             if self.hex {
                 let bytes = val.as_bytes();
-                let (result, consumed) = T::from_radix_16(bytes);
-                (consumed == bytes.len()).then_some(result)
+                let (result, consumed) = atoi::Integer::<T>::from_radix_16(bytes);
+                (consumed == bytes.len()).then_some(result.0)
             } else {
                 val.parse::<T>().ok()
             }

src/window/vip/bgmap.rs

@@ -191,19 +191,19 @@ impl BgMapWindow {
 }
 
 impl AppWindow for BgMapWindow {
-    fn sim_id(&self) -> SimId {
-        self.sim_id
+    fn sim_id(&self) -> Option<SimId> {
+        Some(self.sim_id)
     }
 
     fn initial_viewport(&self) -> ViewportBuilder {
         ViewportBuilder::default()
-            .with_title(format!("BG Map Data ({})", self.sim_id))
+            .with_title("BG Map Data")
             .with_inner_size((640.0, 480.0))
     }
 
     fn show(&mut self, ui: &mut Ui) {
         self.state.load(ui);
-        CentralPanel::default().show_inside(ui, |ui| {
+        CentralPanel::default().show(ui, |ui| {
             ui.horizontal_top(|ui| {
                 StripBuilder::new(ui)
                     .size(Size::relative(0.3).at_most(200.0))

src/window/vip/chardata.rs

@@ -251,19 +251,19 @@ impl CharacterDataWindow {
 }
 
 impl AppWindow for CharacterDataWindow {
-    fn sim_id(&self) -> SimId {
-        self.sim_id
+    fn sim_id(&self) -> Option<SimId> {
+        Some(self.sim_id)
     }
 
     fn initial_viewport(&self) -> ViewportBuilder {
         ViewportBuilder::default()
-            .with_title(format!("Character Data ({})", self.sim_id))
+            .with_title("Character Data")
             .with_inner_size((640.0, 480.0))
     }
 
     fn show(&mut self, ui: &mut Ui) {
         self.state.load(ui);
-        CentralPanel::default().show_inside(ui, |ui| {
+        CentralPanel::default().show(ui, |ui| {
             ui.horizontal_top(|ui| {
                 StripBuilder::new(ui)
                     .size(Size::relative(0.3).at_most(200.0))

src/window/vip/framebuffer.rs

@@ -151,19 +151,19 @@ impl FrameBufferWindow {
 }
 
 impl AppWindow for FrameBufferWindow {
-    fn sim_id(&self) -> SimId {
-        self.sim_id
+    fn sim_id(&self) -> Option<SimId> {
+        Some(self.sim_id)
     }
 
     fn initial_viewport(&self) -> ViewportBuilder {
         ViewportBuilder::default()
-            .with_title(format!("Frame Buffers ({})", self.sim_id))
+            .with_title("Frame Buffers")
             .with_inner_size((640.0, 480.0))
     }
 
     fn show(&mut self, ui: &mut Ui) {
         self.state.load(ui);
-        CentralPanel::default().show_inside(ui, |ui| {
+        CentralPanel::default().show(ui, |ui| {
             ui.horizontal_top(|ui| {
                 StripBuilder::new(ui)
                     .size(Size::relative(0.3).at_most(200.0))

src/window/vip/object.rs

@@ -207,19 +207,19 @@ impl ObjectWindow {
 }
 
 impl AppWindow for ObjectWindow {
-    fn sim_id(&self) -> SimId {
-        self.sim_id
+    fn sim_id(&self) -> Option<SimId> {
+        Some(self.sim_id)
     }
 
     fn initial_viewport(&self) -> ViewportBuilder {
         ViewportBuilder::default()
-            .with_title(format!("Object Data ({})", self.sim_id))
+            .with_title("Object Data")
             .with_inner_size((640.0, 500.0))
     }
 
     fn show(&mut self, ui: &mut Ui) {
         self.state.load(ui);
-        CentralPanel::default().show_inside(ui, |ui| {
+        CentralPanel::default().show(ui, |ui| {
             ui.horizontal_top(|ui| {
                 StripBuilder::new(ui)
                     .size(Size::relative(0.3).at_most(200.0))

src/window/vip/registers.rs

@@ -630,18 +630,18 @@ fn read_address<T: MemoryValue>(registers: &MemoryRef, address: usize) -> T {
 }
 
 impl AppWindow for RegisterWindow {
-    fn sim_id(&self) -> SimId {
-        self.sim_id
+    fn sim_id(&self) -> Option<SimId> {
+        Some(self.sim_id)
     }
 
     fn initial_viewport(&self) -> ViewportBuilder {
         ViewportBuilder::default()
-            .with_title(format!("Registers ({})", self.sim_id))
+            .with_title("Registers")
             .with_inner_size((800.0, 480.0))
     }
 
     fn show(&mut self, ui: &mut Ui) {
-        CentralPanel::default().show_inside(ui, |ui| {
+        CentralPanel::default().show(ui, |ui| {
             ScrollArea::vertical().show(ui, |ui| {
                 ui.horizontal_top(|ui| {
                     let width = ui.available_width();

src/window/vip/utils.rs

@@ -1,6 +1,7 @@
 use egui::{Color32, Image, ImageSource, Response, Sense, TextureOptions, Ui, Widget};
 
 pub const GENERIC_PALETTE: [u8; 4] = [0, 32, 64, 128];
+const COLOR_TRANSPARENT: Color32 = Color32::from_rgb(0x25, 0x25, 0x25);
 
 pub fn shade(brt: u8, color: Color32) -> Color32 {
     let corrected = if brt > 132 {
@@ -44,7 +45,9 @@ pub fn parse_brts(brts: &[u16; 3], color: Color32) -> [Color32; 4] {
 
 pub fn palette_colors(palette: u8, brts: &[u8; 8], color: Color32) -> [Color32; 4] {
     let colors = parse_shades(brts).map(|s| shade(s, color));
-    parse_palette(palette).map(|p| colors[p as usize])
+    let mut palette_colors = parse_palette(palette).map(|p| colors[p as usize]);
+    palette_colors[0] = COLOR_TRANSPARENT;
+    palette_colors
 }
 
 pub struct Object {

src/window/vip/world.rs

@@ -527,19 +527,19 @@ impl WorldWindow {
 }
 
 impl AppWindow for WorldWindow {
-    fn sim_id(&self) -> SimId {
-        self.sim_id
+    fn sim_id(&self) -> Option<SimId> {
+        Some(self.sim_id)
     }
 
     fn initial_viewport(&self) -> ViewportBuilder {
         ViewportBuilder::default()
-            .with_title(format!("Worlds ({})", self.sim_id))
+            .with_title("Worlds")
             .with_inner_size((640.0, 520.0))
     }
 
     fn show(&mut self, ui: &mut Ui) {
         self.state.load(ui);
-        CentralPanel::default().show_inside(ui, |ui| {
+        CentralPanel::default().show(ui, |ui| {
             ui.horizontal_top(|ui| {
                 StripBuilder::new(ui)
                     .size(Size::relative(0.3).at_most(200.0))
@@ -1081,8 +1081,8 @@ impl<'a> SourceCoordCalculator<'a> {
                 (sx, sy)
             }
             SourceParam::Affine(affine) => {
-                let sx = affine_coord(affine.src_x, x, affine.dx, affine.src_parallax.min(0));
-                let sy = affine_coord(affine.src_y, x, affine.dy, affine.src_parallax.min(0));
+                let sx = affine_coord(affine.src_x, x, affine.dx, -(affine.src_parallax.min(0)));
+                let sy = affine_coord(affine.src_y, x, affine.dy, -(affine.src_parallax.min(0)));
                 (sx, sy)
             }
         }