xlib_playground

commit 326d4061b95da2fa868e7ee26a1ee9e60f039d34
parent 270dde44832f0ae876d924dcaf8a32febbfa4e66
Author: Matsuda Kenji <info@mtkn.jp>
Date:   Thu, 22 Dec 2022 12:00:34 +0900

fix fps

Diffstat:
M
ex2/ex2.c
 | 
28
++++++++++++++++++++++++----

1 file changed, 24 insertions(+), 4 deletions(-)
diff --git a/ex2/ex2.c b/ex2/ex2.c
@@ -9,6 +9,7 @@
 /* macros */
 #define INIT_WIDTH 800
 #define INIT_HEIGHT 600
+#define FPS 60
 
 
 /* variables */
@@ -62,11 +63,16 @@ main(void)
 {
 	int px, py;
 	int quit;
+	long t0, t1, dt;
+	int fps_count;
 	struct timespec ts;
 	XEvent event;
 
 	setup();
 	quit = 0;
+	clock_gettime(CLOCK_MONOTONIC, &ts);
+	t0 = ts.tv_nsec;
+	fps_count = 0;
 
 	while (!quit){
 		while(XPending(display) > 0){
@@ -90,7 +96,25 @@ main(void)
 				break;
 			}
 		}
+
+		// fix fps
+		dt = 0;
+		while (dt < 1.0 * 1000 * 1000 * 1000 / FPS){
+			clock_gettime(CLOCK_MONOTONIC, &ts);
+			t1 = ts.tv_nsec;
+			dt = t1 > t0 ? t1 - t0 : t1 - t0 + 1000 * 1000 * 1000;
+		}
+		// count fps.
+		// simple but not precise.
+		fps_count++;
+		if (t1 < t0){
+			printf("fps: %u\n", fps_count);
+			fps_count = 0;
+		}
+
 		clock_gettime(CLOCK_MONOTONIC, &ts);
+		t0 = ts.tv_nsec;
+
 		px = 200 + (int) (100 * sinf(ts.tv_sec + ts.tv_nsec / 1000.0 / 1000 / 1000));
 		py = 200 + (int) (100 * cosf(ts.tv_sec + ts.tv_nsec / 1000.0 / 1000 / 1000));
 		XClearArea(display, window,
@@ -100,10 +124,6 @@ main(void)
 		XFillRectangle(display, window, gc,
 					   px, py,    // position
 					   100, 100);   // width and height
-		
-		ts.tv_sec = 0;
-		ts.tv_nsec = 10 * 1000 * 1000;
-		nanosleep(&ts, NULL);
 	}
 
 	cleanup();