delta_time is now calculating by converting timespec to seconds

src/engine.c

@@ -5,11 +5,27 @@
 #include "corelib/input.h"
 #include "time.h"
 
-static float _delta_time = 0;
+static double _delta_time = 0;
+static double _min_frame_interval = 0;
 static struct timespec start_last_frame;
 
+#define CURRENT_TIME(__out) { struct timespect ts; timespec_get(&ts, TIME_UTC); __out = ts.tv_sec + tv.nsec * 1E-09; }
+
+inline static
+double timespec_to_sec(struct timespec spec) {
+	return spec.tv_sec + spec.tv_nsec;
+}
+
 inline float delta_time() {
-	return _delta_time;
+	return (float)_delta_time;
+}
+
+void set_frame_interval(double frame_interval) {
+	_min_frame_interval = frame_interval;
+}
+
+void set_frame_rate_limit(int fps) {
+	_min_frame_interval = 1.0/(double)fps;
 }
 
 static inline
@@ -58,7 +74,7 @@ int _engine_run() {
 	struct timespec next_time;
 	while(g_context.running) {
 		timespec_get(&next_time, TIME_UTC);
-		_delta_time = (next_time.tv_nsec - start_last_frame.tv_nsec) * 1E-9;
+		_delta_time = timespec_to_sec(next_time) - timespec_to_sec(start_last_frame);
 		if(next_time.tv_nsec < start_last_frame.tv_nsec) _delta_time = 0;
 		start_last_frame = next_time;
 		_handle_events();

src/engine.h

@@ -6,6 +6,8 @@ extern "C" {
 #endif
 
 extern float delta_time();
+extern void set_frame_interval(double frame_interval);
+extern void set_frame_rate_limit(int fps);
 
 /* TO BE DEFINED IN GAME */