From 194bf0e266e32d157eef0e4b1cb00603d87791c7 Mon Sep 17 00:00:00 2001
From: veclavtalica <veclavtalica@poto.cafe>
Date: Mon, 8 Jul 2024 23:47:22 +0300
Subject: [PATCH] util.c: floating point timers for game loop

---
 src/context.h |  1 +
 src/main.c    |  1 +
 src/util.c    | 16 +++++++++++++++-
 src/util.h    | 10 ++++++++++
 4 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/src/context.h b/src/context.h
index 7b4862d..578d1ab 100644
--- a/src/context.h
+++ b/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;
 
diff --git a/src/main.c b/src/main.c
index 053d789..66517a6 100644
--- a/src/main.c
+++ b/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 */
diff --git a/src/util.c b/src/util.c
index f8764cf..ba22cb2 100644
--- a/src/util.c
+++ b/src/util.c
@@ -1,4 +1,5 @@
 #include "util.h"
+#include "context.h"
 
 #include <SDL2/SDL.h>
 #include <physfsrwops.h>
@@ -186,5 +187,18 @@ t_frect to_frect(t_rect rect) {
 
 
 void tick_timer(int *value) {
-     *value = MAX(*value - 1, 0);
+    *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;
 }
diff --git a/src/util.h b/src/util.h
index b7c77e4..17f439f 100644
--- a/src/util.h
+++ b/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