ngl i don't think this is correct

2 files changed, 62 insertions, 4 deletions

diff --git a/examples/platform/platform_x11.c b/examples/platform/platform_x11.c
index 70a827e..4e26165 100644
--- a/examples/platform/platform_x11.c
+++ b/examples/platform/platform_x11.c
@@ -3,6 +3,7 @@
 
 #include <X11/Xlib.h>
 #include <X11/Xutil.h>
+#include <bits/time.h>
 #include <stddef.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -17,8 +18,10 @@
 
 #include "../example.h"
 
-#define DEFAULT_WIDTH 256
-#define DEFAULT_HEIGHT 256
+#define DEFAULT_WIDTH 1280
+#define DEFAULT_HEIGHT 720
+
+#define TARGET_FRAME_TIME_NS 16666667L
 
 static size_t pixels_buffer_count = 0;
 static sponge_Texture canvas = { 0 };
@@ -26,6 +29,28 @@ static float *depths = NULL;
 static Display *dpy;
 static XImage *ximg = NULL;
 
+void timespec_add_ns(struct timespec *inout_t, long ns) {
+    inout_t->tv_nsec += ns;
+    while (inout_t->tv_nsec >= 1000000000L) {
+        inout_t->tv_nsec -= 1000000000L;
+        inout_t->tv_sec += 1;
+    }
+}
+
+long long timespec_sub_ns(struct timespec *a, struct timespec *b) {
+    long long sec = a->tv_sec - b->tv_sec;
+    long long result = a->tv_nsec - b->tv_nsec;
+    result += sec * 1000000000L;
+    return result;
+}
+
+int timespec_cmp(struct timespec *a, struct timespec *b) {
+    if (a->tv_sec < b->tv_sec) return -1;
+    if (a->tv_sec > b->tv_sec) return  1;
+    if (a->tv_nsec < b->tv_nsec) return -1;
+    if (a->tv_nsec > b->tv_nsec) return  1;
+    return 0;
+}
 
 void init_canvas(uint32_t width, uint32_t height) {
     if (ximg) {
@@ -104,12 +129,37 @@ int main() {
     init_canvas(DEFAULT_WIDTH, DEFAULT_HEIGHT);
     init();
 
+    struct timespec ts_next;
+    if (clock_gettime(CLOCK_MONOTONIC, &ts_next)) {
+        fprintf(stderr, "clock_gettime fail\n");
+        return 1;
+    }
+    timespec_add_ns(&ts_next, TARGET_FRAME_TIME_NS);
+
     int running = 1;
     while (running) {
+        if (clock_nanosleep(CLOCK_MONOTONIC, TIMER_ABSTIME, &ts_next, NULL)) {
+            fprintf(stderr, "clock_nanosleep fail\n");
+            return 1;
+        }
+
+        struct timespec ts_now;
+        if (clock_gettime(CLOCK_MONOTONIC, &ts_now)) {
+            fprintf(stderr, "clock_gettime fail\n");
+            return 1;
+        }
+
         if (sponge_texture_valid(canvas)) {
             draw_frame_3d(canvas, depths);
+            struct timespec ts_draw;
+            if (clock_gettime(CLOCK_MONOTONIC, &ts_draw)) {
+                fprintf(stderr, "clock_gettime fail\n");
+                return 1;
+            }
+            long long draw_time = timespec_sub_ns(&ts_draw, &ts_now);
+            fprintf(stderr, "draw time: %3lld.%03lldms\n", draw_time / 1000000, (draw_time % 1000000) / 1000);
+
             XPutImage(dpy, win, gc, ximg, 0, 0, 0, 0, canvas.width, canvas.height);
-            usleep(16000);
         }
 
         while (XPending(dpy)) {
@@ -132,6 +182,14 @@ int main() {
                     break;
             }
         }
+
+        while (timespec_cmp(&ts_next, &ts_now) <= 0) {
+            timespec_add_ns(&ts_next, TARGET_FRAME_TIME_NS);
+            if (clock_gettime(CLOCK_MONOTONIC, &ts_now)) {
+                fprintf(stderr, "clock_gettime fail\n");
+                return 1;
+            }
+        }
     }
 
     if (ximg) {
diff --git a/run_example b/run_example
index 80d6c10..046f066 100755
--- a/run_example
+++ b/run_example
@@ -1,3 +1,3 @@
 #!/bin/bash
 cc -o example examples/platform/platform_x11.c examples/$1 \
-    -lX11 -lm -Wall -Wextra -Wno-type-limits -Wno-pointer-sign -g && ./example
+    -lX11 -lm -Wall -Wextra -Wno-type-limits -Wno-pointer-sign -g -O3 -march=native && ./example