88 lines
2.4 KiB
C++
88 lines
2.4 KiB
C++
#include "game_loop.h"
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#if defined(__EMSCRIPTEN__)
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#include <emscripten/emscripten.h>
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#endif
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namespace fn::game {
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namespace {
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struct LoopRT {
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LoopCfg cfg;
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Uint64 last_ticks;
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float accumulator;
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Uint64 perf_freq;
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};
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#if defined(__EMSCRIPTEN__)
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static LoopRT g_rt;
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void em_tick() {
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LoopRT& rt = g_rt;
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Uint64 now = SDL_GetPerformanceCounter();
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float frame_time = (float)((double)(now - rt.last_ticks) / (double)rt.perf_freq);
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rt.last_ticks = now;
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float cap = rt.cfg.fixed_dt * (float)rt.cfg.max_steps_per_frame;
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if (frame_time > cap) frame_time = cap;
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rt.accumulator += frame_time;
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int steps = 0;
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while (rt.accumulator >= rt.cfg.fixed_dt && steps < rt.cfg.max_steps_per_frame) {
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if (rt.cfg.on_fixed_update) rt.cfg.on_fixed_update(rt.cfg.user, rt.cfg.fixed_dt);
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rt.accumulator -= rt.cfg.fixed_dt;
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steps++;
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}
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float interp = rt.accumulator / rt.cfg.fixed_dt;
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if (rt.cfg.on_render) rt.cfg.on_render(rt.cfg.user, interp);
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if (rt.cfg.should_quit && rt.cfg.should_quit(rt.cfg.user)) {
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emscripten_cancel_main_loop();
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}
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}
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#endif
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} // namespace
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void loop_run(SDL_Window* /*win*/, const LoopCfg& cfg) {
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if (!cfg.on_fixed_update && !cfg.on_render) return;
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#if defined(__EMSCRIPTEN__)
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g_rt.cfg = cfg;
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g_rt.last_ticks = SDL_GetPerformanceCounter();
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g_rt.accumulator = 0.0f;
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g_rt.perf_freq = SDL_GetPerformanceFrequency();
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emscripten_set_main_loop(em_tick, 0, 1);
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#else
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Uint64 perf_freq = SDL_GetPerformanceFrequency();
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Uint64 last = SDL_GetPerformanceCounter();
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float accumulator = 0.0f;
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for (;;) {
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if (cfg.should_quit && cfg.should_quit(cfg.user)) break;
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Uint64 now = SDL_GetPerformanceCounter();
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float frame_time = (float)((double)(now - last) / (double)perf_freq);
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last = now;
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float cap = cfg.fixed_dt * (float)cfg.max_steps_per_frame;
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if (frame_time > cap) frame_time = cap;
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accumulator += frame_time;
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int steps = 0;
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while (accumulator >= cfg.fixed_dt && steps < cfg.max_steps_per_frame) {
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if (cfg.on_fixed_update) cfg.on_fixed_update(cfg.user, cfg.fixed_dt);
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accumulator -= cfg.fixed_dt;
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steps++;
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}
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float interp = accumulator / cfg.fixed_dt;
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if (cfg.on_render) cfg.on_render(cfg.user, interp);
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}
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#endif
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}
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} // namespace fn::game
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