[PATCH 2/2] gears: show FPS count (as in glxgears from mesa/demos)

[Olivier Blin]

---
 clients/gears.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/clients/gears.c b/clients/gears.c
index 70ec86c..8e7d4df 100644
--- a/clients/gears.c
+++ b/clients/gears.c
@@ -59,6 +59,8 @@ struct gears {
 
 	GLint gear_list[3];
 	int fullscreen;
+	int frames;
+	struct timespec last_fps;
 };
 
 struct gear_template {
@@ -203,10 +205,37 @@ make_gear(const struct gear_template *t)
 }
 
 static void
+update_fps(struct gears *gears)
+{
+	struct timespec now;
+	long diff_ms;
+
+	gears->frames++;
+
+	clock_gettime(CLOCK_MONOTONIC, &now);
+
+	diff_ms = (now.tv_sec - gears->last_fps.tv_sec) * 1000 +
+		  (now.tv_nsec - gears->last_fps.tv_nsec) / 1000000;
+
+	if (diff_ms > 5000) {
+		float seconds = diff_ms / 1000.0;
+		float fps = gears->frames / seconds;
+
+		printf("%d frames in %6.3f seconds = %6.3f FPS\n", gears->frames, seconds, fps);
+		fflush(stdout);
+
+		gears->frames = 0;
+		gears->last_fps = now;
+	}
+}
+
+static void
 frame_callback(void *data, struct wl_callback *callback, uint32_t time)
 {
 	struct gears *gears = data;
 
+	update_fps(gears);
+
 	gears->angle = (GLfloat) (time % 8192) * 360 / 8192.0;
 
 	window_schedule_redraw(gears->window);
@@ -407,6 +436,8 @@ gears_create(struct display *display)
 	gears->view.rotx = 20.0;
 	gears->view.roty = 30.0;
 
+	clock_gettime(CLOCK_MONOTONIC, &gears->last_fps);
+
 	glEnable(GL_NORMALIZE);
 
 	glMatrixMode(GL_PROJECTION);
-- 
1.7.11.3

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