1 files changed, 86 insertions, 0 deletions
diff --git a/src/crepe/api/LoopTimer.cpp b/src/crepe/api/LoopTimer.cpp
new file mode 100644
index 0000000..8f09e41
--- /dev/null
+++ b/src/crepe/api/LoopTimer.cpp
@@ -0,0 +1,86 @@
+#include <chrono>
+
+#include "../facade/SDLContext.h"
+#include "../util/log.h"
+
+#include "LoopTimer.h"
+
+using namespace crepe;
+
+LoopTimer::LoopTimer() { dbg_trace(); }
+
+LoopTimer & LoopTimer::get_instance() {
+	static LoopTimer instance;
+	return instance;
+}
+
+void LoopTimer::start() {
+	this->last_frame_time = std::chrono::steady_clock::now();
+	this->elapsed_time = std::chrono::milliseconds(0);
+	this->elapsed_fixed_time = std::chrono::milliseconds(0);
+	this->delta_time = std::chrono::milliseconds(0);
+}
+
+void LoopTimer::update() {
+	auto current_frame_time = std::chrono::steady_clock::now();
+	// Convert to duration in seconds for delta time
+	this->delta_time
+		= std::chrono::duration_cast<std::chrono::duration<double>>(
+			current_frame_time - last_frame_time);
+
+	if (this->delta_time > this->maximum_delta_time) {
+		this->delta_time = this->maximum_delta_time;
+	}
+
+	this->delta_time *= this->game_scale;
+	this->elapsed_time += this->delta_time;
+	this->last_frame_time = current_frame_time;
+}
+
+double LoopTimer::get_delta_time() const { return this->delta_time.count(); }
+
+double LoopTimer::get_current_time() const {
+	return this->elapsed_time.count();
+}
+
+void LoopTimer::advance_fixed_update() {
+	this->elapsed_fixed_time += this->fixed_delta_time;
+}
+
+double LoopTimer::get_fixed_delta_time() const {
+	return this->fixed_delta_time.count();
+}
+
+void LoopTimer::set_fps(int fps) {
+	this->fps = fps;
+	// target time per frame in seconds
+	this->frame_target_time = std::chrono::seconds(1) / fps;
+}
+
+int LoopTimer::get_fps() const { return this->fps; }
+
+void LoopTimer::set_game_scale(double value) { this->game_scale = value; }
+
+double LoopTimer::get_game_scale() const { return this->game_scale; }
+void LoopTimer::enforce_frame_rate() {
+	std::chrono::steady_clock::time_point current_frame_time
+		= std::chrono::steady_clock::now();
+	std::chrono::milliseconds frame_duration
+		= std::chrono::duration_cast<std::chrono::milliseconds>(
+			current_frame_time - this->last_frame_time);
+
+	if (frame_duration < this->frame_target_time) {
+		std::chrono::milliseconds delay_time
+			= std::chrono::duration_cast<std::chrono::milliseconds>(
+				this->frame_target_time - frame_duration);
+		if (delay_time.count() > 0) {
+			SDLContext::get_instance().delay(delay_time.count());
+		}
+	}
+
+	this->last_frame_time = current_frame_time;
+}
+
+double LoopTimer::get_lag() const {
+	return (this->elapsed_time - this->elapsed_fixed_time).count();
+}