lemur/game.c

#include <assets.h>
#include <game.h>
#include <SDL2/SDL.h>
#include <stdbool.h>
#include <time.h>

int sleepNanos(long int ns) {
    struct timespec time;
    time.tv_sec = ns / 1000000000;
    time.tv_nsec = ns % 1000000000;
    return nanosleep(&time, NULL);
}

typedef struct {
    GraphicsContext *gfx;
} GameState;

int onFrame(VB *sim) {
    static uint8_t leftEye[384*224];
    static uint8_t rightEye[384*224];
    GameState *state;
    GraphicsContext *gfx;

    state = vbGetUserData(sim);
    gfx = state->gfx;
    
    vbGetPixels(sim, leftEye, 1, 384, rightEye, 1, 384);
    gfxUpdateLeftEye(gfx, leftEye);
    gfxUpdateRightEye(gfx, rightEye);
    gfxRender(gfx);
    return 1;
}

#define MAX_STEP_CLOCKS 20000000

int runGame(VB *sim, GraphicsContext *gfx) {
    uint32_t clocks;
    SDL_Event event;
    GameState state;
    uint64_t ticks, prevTicks;

    state.gfx = gfx;
    vbSetUserData(sim, &state);
    vbSetFrameCallback(sim, &onFrame);

    gfxUpdateLeftEye(gfx, LEFT_EYE_DEFAULT);
    gfxUpdateRightEye(gfx, RIGHT_EYE_DEFAULT);

    prevTicks = SDL_GetTicks64();
    while (1) {
        clocks = MAX_STEP_CLOCKS;
        vbEmulate(sim, &clocks);
        ticks = SDL_GetTicks64();
        while (SDL_PollEvent(&event)) {
            if (event.type == SDL_QUIT) {
                return 0;
            }
        }
        sleepNanos(((MAX_STEP_CLOCKS - clocks) * 50) - (ticks - prevTicks) * 1000);
        prevTicks = ticks;
    }
}