util.c: floating point timers for game loop

src/context.h

@@ -39,6 +39,7 @@ typedef struct context {
     int64_t frame_accumulator;
     int64_t delta_averager_residual; 
     int64_t time_averager[4];
+    int64_t delta_time; /* preserves real time frame delta with no manipilation */
     uint64_t tick_count;
     uint64_t step_count;
 

src/main.c

@@ -56,6 +56,7 @@ void main_loop(void) {
     int64_t current_frame_time = SDL_GetPerformanceCounter();
     int64_t delta_time = current_frame_time - ctx.prev_frame_time;
     ctx.prev_frame_time = current_frame_time;
+    ctx.delta_time = delta_time;
 
     /* handle unexpected timer anomalies (overflow, extra slow frames, etc) */
     if (delta_time > ctx.desired_frametime * 8) { /* ignore extra-slow frames */

src/util.c

@@ -1,4 +1,5 @@
 #include "util.h"
+#include "context.h"
 
 #include <SDL2/SDL.h>
 #include <physfsrwops.h>
@@ -188,3 +189,16 @@ t_frect to_frect(t_rect rect) {
 void tick_timer(int *value) {
     *value = MAX(*value - 1, 0);
 }
+
+void tick_ftimer(float *value) {
+    *value = MAX(*value - ((float)ctx.delta_time / (float)ctx.clocks_per_second), 0.0f);
+}
+
+bool tick_ftimer_repeat(float *value, float at) {
+    *value -= (float)ctx.delta_time / (float)ctx.clocks_per_second;
+    if (*value < 0.0f) {
+        *value += at;
+        return true;
+    }
+    return false;
+}

src/util.h

@@ -118,4 +118,14 @@ typedef struct fvec2 {
 void tick_timer(int *value);
 
 
+/* decrements a floating point second-based timer, stopping at 0.0 */
+/* meant for poll based real time logic in game logic */
+/* note that it should be decremented only on the next tick after its creation */
+void tick_ftimer(float *value);
+
+/* same as `tick_ftimer` but instaed of clamping it repeats */
+/* returns true if value was cycled */
+bool tick_ftimer_repeat(float *value, float at);
+
+
 #endif