From da74a60d20d46a54eda8158f01e174611d1d8962 Mon Sep 17 00:00:00 2001
From: Sam Anthony <sam@samanthony.xyz>
Date: Fri, 11 Oct 2024 11:28:43 -0400
Subject: stabilize framerate

---
 balls.cpp | 12 +++++++++++-
 balls.h   |  1 +
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/balls.cpp b/balls.cpp
index 3b5b902..939df7b 100644
--- a/balls.cpp
+++ b/balls.cpp
@@ -197,6 +197,11 @@ volume(double radius) {
 
 void
 animate(int v) {
+	clock_t tstart, elapsed;
+	unsigned int nextFrame;
+
+	tstart = clock();
+
 	/* Update position. */
 	parallel_for(size_t(0), balls.size(), [] (size_t i) {
 		balls[i]->v.y -=G;
@@ -216,5 +221,10 @@ animate(int v) {
 	});
 
 	display();
-	glutTimerFunc(FRAME_TIME_MS, animate, 0);
+
+	elapsed = (clock() - tstart) / (CLOCKS_PER_SEC / MS_PER_S);
+		/* time taken to draw this frame [ms] */
+	nextFrame = (elapsed > FRAME_TIME_MS) ? 0 : FRAME_TIME_MS-elapsed;
+		/* when to start drawing the next frame [ms] */
+	glutTimerFunc(nextFrame, animate, 0);
 }
diff --git a/balls.h b/balls.h
index 4d070c9..92ae8dd 100644
--- a/balls.h
+++ b/balls.h
@@ -1,6 +1,7 @@
 #include <stdlib.h>
 #include <iostream>
 #include <math.h>
+#include <time.h>
 #include <GL/glut.h>
 #include <oneapi/tbb.h>
 
-- 
cgit v1.2.3