Frame Interp: Game Clock Refactor & Ring Item Selection

src/dusk/game_clock.cpp

@@ -0,0 +1,76 @@
+#include "dusk/game_clock.h"
+
+#include <algorithm>
+#include <chrono>
+#include <unordered_map>
+
+namespace dusk {
+namespace game_clock {
+
+using clock = std::chrono::steady_clock;
+
+bool s_initialized = false;
+clock::time_point s_previous_sample{};
+float s_sim_accumulator = 0.0f;
+
+std::unordered_map<uintptr_t, clock::time_point> s_interval_last_sample;
+
+void ensure_initialized() {
+    if (s_initialized) {
+        return;
+    }
+    s_previous_sample = clock::now();
+    s_sim_accumulator = sim_pace();
+    s_initialized = true;
+}
+
+void reset_accumulator() {
+    ensure_initialized();
+    s_sim_accumulator = 0.0f;
+}
+
+MainLoopPacer advance_main_loop() {
+    ensure_initialized();
+
+    const clock::time_point now = clock::now();
+    const float presentation_dt = std::chrono::duration<float>(now - s_previous_sample).count();
+    s_previous_sample = now;
+
+    s_sim_accumulator += presentation_dt;
+
+    MainLoopPacer out{};
+    out.presentation_dt_seconds = presentation_dt;
+
+    const bool should_interpolate = dusk::getSettings().game.enableFrameInterpolation && !dusk::getTransientSettings().skipFrameRateLimit;
+    out.is_interpolating = should_interpolate;
+    out.sim_pace = sim_pace();
+
+    if (!should_interpolate) {
+        s_sim_accumulator = 0.0f;
+        out.do_sim_tick = true;
+        out.interpolation_step = 0.0f;
+        return out;
+    } else {
+        out.do_sim_tick = s_sim_accumulator >= sim_pace();
+        out.interpolation_step = out.do_sim_tick ? 0.0f : s_sim_accumulator / sim_pace();
+        return out;
+    }
+}
+
+float consume_interval(const void* consumer) {
+    ensure_initialized();
+    const uintptr_t key = reinterpret_cast<uintptr_t>(consumer);
+    const clock::time_point now = clock::now();
+
+    float dt = ui_initial_dt();
+    const auto it = s_interval_last_sample.find(key);
+    if (it != s_interval_last_sample.end()) {
+        dt = std::chrono::duration<float>(now - it->second).count();
+        dt = std::min(dt, ui_maximum_dt());
+    }
+    s_interval_last_sample[key] = now;
+    return dt;
+}
+
+}  // namespace game_clock
+}  // namespace dusk