From a9490274d79ecf0d7d9872c23ca4db1ac46570e6 Mon Sep 17 00:00:00 2001
From: Leo Tenenbaum <pommicket@gmail.com>
Date: Fri, 5 Feb 2021 12:37:43 -0500
Subject:  sleep before SDL_GL_SwapWindow to stop busy loop

---
 gl.c   |  1 +
 main.c | 17 +++++++++++------
 2 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/gl.c b/gl.c
index 5ef3360..a9850cd 100644
--- a/gl.c
+++ b/gl.c
@@ -16,6 +16,7 @@
 	do(VIEWPORT, Viewport)\
 	do(CLEARCOLOR, ClearColor)\
 	do(CLEAR, Clear)\
+	do(FINISH, Finish)\
 	do(CREATESHADER, CreateShader)\
 	do(DELETESHADER, DeleteShader)\
 	do(CREATEPROGRAM, CreateProgram)\
diff --git a/main.c b/main.c
index bba3b6b..22e7786 100644
--- a/main.c
+++ b/main.c
@@ -341,7 +341,7 @@ int main(int argc, char **argv) {
 	#if DEBUG
 		//printf("\033[H\033[2J");
 	#endif
-		PROFILE_TIME(frame_start);
+		double frame_start = time_get_seconds();
 
 
 		SDL_Event event;
@@ -643,19 +643,24 @@ int main(int argc, char **argv) {
 				buffer_check_valid(&ted->buffers[i]);
 		buffer_check_valid(&ted->line_buffer);
 	#endif
-
-		PROFILE_TIME(frame_end_noswap);
-
+	
+		glFinish();
+		
+		double frame_end_noswap = time_get_seconds();
 	#if PROFILE
 		{
 			print("Frame (noswap): %.1f ms\n", (frame_end_noswap - frame_start) * 1000);
 		}
 	#endif
-
-
+	
+		u32 ms_wait = (u32)((frame_end_noswap - frame_start) * 1000);
+		if (ms_wait) ms_wait -= 1; // give swap an extra ms to make sure it's actually vsynced
+		SDL_Delay(ms_wait);
 		SDL_GL_SwapWindow(window);
 		PROFILE_TIME(frame_end);
 
+		assert(glGetError() == 0);
+
 	#if PROFILE
 		{
 			print("Frame: %.1f ms\n", (frame_end - frame_start) * 1000);
-- 
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