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#include <stddef.h>
#include <stdint.h>
typedef struct {
int x, y, w, h;
unsigned char r, g, b, a;
} DrawElement;
typedef struct {
int len;
DrawElement els[256];
} DrawList;
#define MEM_SIZE (1<<16)
typedef struct {
char *start;
char *end;
} Arena;
#define new(a, c, t) ((t *) alloc(a, c, sizeof(t), _Alignof(t)))
#define affirm(c) while (!(c)) *(volatile int *)0 = 0
static void *alloc(Arena *a, ptrdiff_t count, ptrdiff_t size, ptrdiff_t align) {
ptrdiff_t pad = -(size_t) a->start & (align - 1);
affirm(count < (a->end - a->start - pad) / size);
char *r = a->start + pad;
a->start += pad + size * count;
for (ptrdiff_t i = 0; i < count * size; i++) {
r[i] = 0;
}
return r;
}
typedef struct {
int width, height;
} UI;
typedef struct {
int x, y;
} State;
// Mirror these in src/index.html.in
enum {
INPUT_NONE,
INPUT_UP,
INPUT_DOWN,
INPUT_LEFT,
INPUT_RIGHT,
};
typedef struct {
State state;
UI ui;
int input;
} Game;
static DrawList *render(State state, UI *ui, Arena *a) {
(void) ui;
DrawList *drawList = new(a, 1, DrawList);
drawList->len = 1;
drawList->els[0] = (DrawElement) {
.x = state.x,
.y = state.y,
.w = 100,
.h = 100,
.r = 255,
.g = 0,
.b = 0,
.a = 255,
};
return drawList;
}
static void update(Game *game, Arena a) {
switch (game->input) {
case INPUT_UP:
game->state.y -= 20;
break;
case INPUT_DOWN:
game->state.y += 20;
break;
case INPUT_LEFT:
game->state.x -= 20;
break;
case INPUT_RIGHT:
game->state.x += 20;
break;
default:
break;
}
}
#if SDL
#include <SDL3/SDL.h>
int main(int argc, char **argv) {
(void) argc;
(void) argv;
char *mem = SDL_malloc(MEM_SIZE);
Arena a = {
.start = mem,
.end = mem + MEM_SIZE,
};
Game *game = new(&a, 1, Game);
game->state = (State) {
.x = 100,
.y = 100,
};
game->ui = (UI) {
.width = 640,
.height = 480,
};
SDL_Init(SDL_INIT_VIDEO);
SDL_Window *w = SDL_CreateWindow(
"LDJam 57",
game->ui.width,
game->ui.height,
0
);
SDL_PropertiesID renderProps = SDL_CreateProperties();
SDL_SetPointerProperty(renderProps, SDL_PROP_RENDERER_CREATE_WINDOW_POINTER, w);
SDL_SetNumberProperty(renderProps, SDL_PROP_RENDERER_CREATE_PRESENT_VSYNC_NUMBER, 1);
SDL_Renderer *r = SDL_CreateRendererWithProperties(renderProps);
SDL_DestroyProperties(renderProps);
for (;;) {
game->input = INPUT_NONE;
SDL_Event e = {0};
while (SDL_PollEvent(&e)) {
switch (e.type) {
case SDL_EVENT_QUIT:
return 0;
case SDL_EVENT_KEY_DOWN:
switch (e.key.key) {
case 'w':
game->input = INPUT_UP;
break;
case 'a':
game->input = INPUT_LEFT;
break;
case 's':
game->input = INPUT_DOWN;
break;
case 'd':
game->input = INPUT_RIGHT;
break;
}
break;
}
}
Arena scratch = a;
DrawList *drawList = render(game->state, &game->ui, &scratch);
SDL_SetRenderDrawColor(r, 0, 0, 0, 255);
SDL_RenderFillRect(r, NULL);
for (int i = 0; i < drawList->len; i++) {
SDL_SetRenderDrawColor(
r,
drawList->els[i].r,
drawList->els[i].g,
drawList->els[i].b,
drawList->els[i].a
);
SDL_FRect rect = {
.x = (float) drawList->els[i].x,
.y = (float) drawList->els[i].y,
.w = (float) drawList->els[i].w,
.h = (float) drawList->els[i].h
};
SDL_RenderFillRect(r, &rect);
}
update(game, a);
SDL_RenderPresent(r);
}
return 0;
}
#elif WASM
static Game *game;
static Arena perm;
__attribute((export_name("game_init")))
void game_init(void) {
static char heap[MEM_SIZE];
perm.start = heap;
perm.end = heap + MEM_SIZE;
game = new(&perm, 1, Game);
game->state = (State) {
.x = 100,
.y = 100,
};
}
__attribute((export_name("game_render")))
DrawList *game_render(int width, int height) {
game->ui.width = width;
game->ui.height = height;
Arena scratch = perm;
return render(game->state, &game->ui, &scratch);
}
__attribute((export_name("game_update")))
void game_update(int input) {
game->input = input;
update(game, perm);
}
#endif
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