xlib_playground

commit 1c42784c3c3c5db42e097593e2de647fda0e27c5
parent bcdf5c55490c0b00a0f62529509ad35b971bb57e
Author: Matsuda Kenji <info@mtkn.jp>
Date:   Fri, 16 Dec 2022 15:16:15 +0900

accurate fps

Diffstat:
M
main.c
 | 
32
+++++++++++++++++++++++++-------

1 file changed, 25 insertions(+), 7 deletions(-)
diff --git a/main.c b/main.c
@@ -50,7 +50,7 @@ void start_menu(void);
 void game_init(void);
 void game_play(void);
 void end_menu(void);
-void next_tick(void);
+void next_tick(float);
 void cleanup(void);
 
 void
@@ -143,7 +143,15 @@ game_init(void)
 void
 game_play(void)
 {
+	long t0, t1, dt;
+	long t2; // for frame count
+	struct timespec ts;
+
 	game_init();
+
+	clock_gettime(CLOCK_MONOTONIC, &ts);
+	t0 = t2 = ts.tv_nsec;
+
 	while (next_menu == Game_Play){
 		while (XPending(display) > 0) {
 			XEvent event;
@@ -209,14 +217,24 @@ game_play(void)
 		win_width = window_attributes_return.width;
 		win_height = window_attributes_return.height;
 
-		next_tick();
+		clock_gettime(CLOCK_MONOTONIC, &ts);
+		t1 = ts.tv_nsec;
+		dt = t1 - t0 > 0 ? t1 - t0 : t1 - t0 + 1000 * 1000 * 1000;
+		while(dt < 1.0/FPS * 1000 * 1000 * 1000){
+			clock_gettime(CLOCK_MONOTONIC, &ts);
+			t1 = ts.tv_nsec;
+			dt = t1 - t0 > 0 ? t1 - t0 : t1 - t0 + 1000 * 1000 * 1000;
+		}
+		next_tick(1.0/FPS);
+		clock_gettime(CLOCK_MONOTONIC, &ts);
+		t0 = ts.tv_nsec;
+		dt = t0 - t2 > 0 ? t0 - t2 : t0 - t2 + 1000 * 1000 * 1000;
+		printf("fps: %f\n", 1.0 / ((double) dt / 1000 / 1000 / 1000));
+		t2 = t0;
 
 		XClearArea(display, window, 0, 0, win_width, win_height, False);
 		XFillRectangle(display, window, gc, square.px, square.py, square.width, square.height);
 		XDrawString(display, window, fgc, square.px, square.py, "player", 6);
-
-		struct timespec timetosleep = {0, 1000*1000*1000/FPS}; //not accurate
-		nanosleep(&timetosleep, NULL);
 	}
 }
 
@@ -227,7 +245,7 @@ end_menu(void)
 }
 
 void
-next_tick(void)
+next_tick(float dt)
 {
 	square.vx = 0;
 	if (key_state[Key_D] == Key_Down)
@@ -240,7 +258,7 @@ next_tick(void)
 		square.vy = -1000;
 	}
 
-	obj_next_tick(&square, 1.0/FPS);
+	obj_next_tick(&square, dt);
 
 	if (square.px <= 0){
 		square.px = 0;