From 722aa81936c786ad072cec2d189c551a6e246986 Mon Sep 17 00:00:00 2001
From: taw27 <taw27@84d2e878-0bd5-11dd-ad15-13eda11d74c5>
Date: Thu, 7 Aug 2008 23:13:05 +0000
Subject: Sleep for the right amount of time

git-svn-id: svn://cook.msm.cam.ac.uk:745/thrust3d/thrust3d@231 84d2e878-0bd5-11dd-ad15-13eda11d74c5
---
 src/game.c   |  4 +++-
 src/main.c   |  7 ++-----
 src/render.c | 25 +++++++++++++------------
 src/types.h  |  4 ++++
 4 files changed, 22 insertions(+), 18 deletions(-)

diff --git a/src/game.c b/src/game.c
index e8d69b9..a5727be 100644
--- a/src/game.c
+++ b/src/game.c
@@ -291,12 +291,14 @@ Game *game_new(int width, int height, GameOptions gameopts) {
 	g->frames = 0;
 	g->t_fps = SDL_GetTicks();
 	g->fps = 0;
+	g->query_this_frame = 1;
+	g->time_to_render = 0;
 	g->fuel = 1.0;
 	g->radiation = 0.1;
 	g->platform_rel_x = 0.0;
 	g->platform_rel_y = 0.0;
 	g->time_of_landing_event = -1500.0;	/* Force the platform recharge ripple to be 'bright' */
-		
+	
 	/* Renderer setup */
 	g->render = render_setup(width, height, gameopts.disable_vbos, gameopts.disable_fbos, gameopts.disable_shaders);
 	if ( g->render == NULL ) {
diff --git a/src/main.c b/src/main.c
index 2878c7f..7d87fd6 100644
--- a/src/main.c
+++ b/src/main.c
@@ -292,11 +292,8 @@ int main(int argc, char *argv[]) {
 			game->frames = 0;
 		}
 		
-		/* Sleep for a bit to avoid hogging the CPU.
-		 * This is a fudge - ideally this delay would adapt so that the CPU is not hogged when the GPU is the
-		 * limiting factor, and be zero when the CPU is limiting.  I don't know of a sensible way to tell which
-		 * is the case.	 */
-		if ( !gameopts.no_framerate_limit ) usleep(30000);
+		/* Wait for how long it takes to render the frame at the most recent measurement. */
+		if ( !gameopts.no_framerate_limit ) usleep(game->time_to_render/1000);
 		
 	}
 	
diff --git a/src/render.c b/src/render.c
index f7a2be3..4b95635 100644
--- a/src/render.c
+++ b/src/render.c
@@ -555,13 +555,12 @@ void render_draw(Game *game, Uint32 t) {
 	GLfloat amb[] = { 0.0, 0.0, 0.0, 1.0 };
 	GLfloat fx, fy, fz;
 	GLfloat fxt, fyt, fzt;
-	GLuint timer_query;
 	
 	r = game->render;
 	
-	if ( game->frames == 1 ) {
-		glGenQueries(1, &timer_query);
-		glBeginQuery(GL_TIME_ELAPSED_EXT, timer_query);
+	if ( game->query_this_frame ) {
+		glGenQueries(1, &game->timer_query);
+		glBeginQuery(GL_TIME_ELAPSED_EXT, game->timer_query);
 	}
 	
 	if ( r->fbos ) {
@@ -680,18 +679,20 @@ void render_draw(Game *game, Uint32 t) {
 	
 	render_draw_2d(r, game);
 	
-	if ( game->frames == 1 ) glEndQuery(GL_TIME_ELAPSED_EXT);
+	if ( game->query_this_frame) glEndQuery(GL_TIME_ELAPSED_EXT);
 	
 	SDL_GL_SwapBuffers();
 	
-	if ( game->frames == 1 ) {
-		GLint available = 0;
-		GLuint64EXT timeelapsed;
-		while (!available) {
-			glGetQueryObjectiv(timer_query, GL_QUERY_RESULT_AVAILABLE, &available);
+	if ( !game->query_this_frame ) {
+		GLint available;
+		glGetQueryObjectiv(game->timer_query, GL_QUERY_RESULT_AVAILABLE, &available);
+		if ( available ) {
+			glGetQueryObjectui64vEXT(game->timer_query, GL_QUERY_RESULT, &game->time_to_render);
+			game->query_this_frame = 1;
+			glDeleteQueries(1, &game->timer_query);
 		}
-		glGetQueryObjectui64vEXT(timer_query, GL_QUERY_RESULT, &timeelapsed);
-		printf("Frame took %lli ms to render\n", (long long int)(timeelapsed/1e6));
+	} else {
+		game->query_this_frame = 0;
 	}
 		
 }
diff --git a/src/types.h b/src/types.h
index 550d931..37ccf1f 100644
--- a/src/types.h
+++ b/src/types.h
@@ -259,9 +259,13 @@ typedef struct {
 	int paused;
 	int pause_rel;
 	
+	/* Performance monitoring stuff */
 	int		frames;
 	Uint32		t_fps;
 	int		fps;
+	int		query_this_frame;
+	GLuint		timer_query;
+	GLuint64EXT	time_to_render;
 	
 	GLfloat		radiation;
 	GLfloat		fuel;
-- 
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