use OpenGL swap interval on Windows and X11

src/MiniFB_internal.c

@@ -102,3 +102,12 @@ resize_dst(SWindowData *window_data, uint32_t width, uint32_t height) {
     window_data->dst_width    = (uint32_t) (width  * window_data->factor_width);
     window_data->dst_height   = (uint32_t) (height * window_data->factor_height);
 }
+
+#if !defined(USE_OPENGL_API)
+
+//-------------------------------------
+void
+set_target_fps_aux() {
+}
+
+#endif

src/MiniFB_internal.h

@@ -20,6 +20,7 @@ extern "C" {
 
     void calc_dst_factor(SWindowData *window_data, uint32_t width, uint32_t height);
     void resize_dst(SWindowData *window_data, uint32_t width, uint32_t height);
+    void set_target_fps_aux();
 
 #if defined(__cplusplus)
 }

src/MiniFB_timer.c

@@ -6,6 +6,7 @@
 double      g_timer_frequency;
 double      g_timer_resolution;
 double      g_time_for_frame = 1.0 / 60.0;
+bool        g_use_hardware_sync = false;
 
 //-------------------------------------
 extern uint64_t mfb_timer_tick(void);
@@ -20,6 +21,7 @@ mfb_set_target_fps(uint32_t fps) {
     else {
         g_time_for_frame = 1.0 / fps;
     }
+    set_target_fps_aux();
 }
 
 //-------------------------------------

src/gl/MiniFB_GL.c

@@ -1,6 +1,7 @@
 #if defined(USE_OPENGL_API)
 
 #include "MiniFB_GL.h"
+#include "MiniFB_internal.h"
 #if defined(_WIN32) || defined(WIN32)
     #include <windows/WindowData_Win.h>
     #include <gl/gl.h>
@@ -19,6 +20,10 @@
     #define UseCleanUp(x)
 #endif
 
+extern double   g_time_for_frame;
+extern bool     g_use_hardware_sync;
+
+
 //-------------------------------------
 #if defined(_WIN32) || defined(WIN32)
 bool
@@ -59,6 +64,44 @@ setup_pixel_format(HDC hDC) {
 
     return true;
 }
+
+typedef BOOL (WINAPI * PFNWGLSWAPINTERVALEXTPROC)(int);
+typedef int (WINAPI * PFNWGLGETSWAPINTERVALEXTPROC)(void);
+PFNWGLSWAPINTERVALEXTPROC       SwapIntervalEXT    = 0x0;
+PFNWGLGETSWAPINTERVALEXTPROC    GetSwapIntervalEXT = 0x0;
+
+#elif defined(linux)
+
+bool
+setup_pixel_format(SWindowData_X11 *window_data_x11) {
+    GLint glxAttribs[] = {
+        GLX_RGBA,
+        GLX_DOUBLEBUFFER,
+        GLX_DEPTH_SIZE,     24,
+        GLX_STENCIL_SIZE,   8,
+        GLX_RED_SIZE,       8,
+        GLX_GREEN_SIZE,     8,
+        GLX_BLUE_SIZE,      8,
+        GLX_DEPTH_SIZE,     24,
+        GLX_STENCIL_SIZE,   8,
+        GLX_SAMPLE_BUFFERS, 0,
+        GLX_SAMPLES,        0,
+        None
+    };
+
+    XVisualInfo* visualInfo = glXChooseVisual(window_data_x11->display, window_data_x11->screen, glxAttribs);
+    if (visualInfo == 0) {
+        fprintf(stderr, "Could not create correct visual window.\n");
+        XCloseDisplay(window_data_x11->display);
+        return false;
+    }
+
+    return true;
+}
+
+typedef void (*PFNGLXSWAPINTERVALEXTPROC)(Display*,GLXDrawable,int);
+PFNGLXSWAPINTERVALEXTPROC   SwapIntervalEXT = 0x0;
+
 #endif
 
 //-------------------------------------
@@ -69,10 +112,15 @@ create_GL_context(SWindowData *window_data) {
 
     if (setup_pixel_format(window_data_win->hdc) == false)
         return false;
+
     window_data_win->hGLRC = wglCreateContext(window_data_win->hdc);
     wglMakeCurrent(window_data_win->hdc, window_data_win->hGLRC);
     init_GL(window_data);
 
+    SwapIntervalEXT    = (PFNWGLSWAPINTERVALEXTPROC)    wglGetProcAddress("wglSwapIntervalEXT");
+    GetSwapIntervalEXT = (PFNWGLGETSWAPINTERVALEXTPROC) wglGetProcAddress("wglGetSwapIntervalEXT");
+    set_target_fps_aux();
+
     return true;
 
 #elif defined(linux)
@@ -89,26 +137,8 @@ create_GL_context(SWindowData *window_data) {
         //fprintf(stdout, "GLX version: %d.%d\n", majorGLX, minorGLX);
     }
 
-    GLint glxAttribs[] = {
+    if (setup_pixel_format(window_data_x11) == false)
-        GLX_RGBA,
-        GLX_DOUBLEBUFFER,
-        GLX_DEPTH_SIZE,     24,
-        GLX_STENCIL_SIZE,   8,
-        GLX_RED_SIZE,       8,
-        GLX_GREEN_SIZE,     8,
-        GLX_BLUE_SIZE,      8,
-        GLX_DEPTH_SIZE,     24,
-        GLX_STENCIL_SIZE,   8,
-        GLX_SAMPLE_BUFFERS, 0,
-        GLX_SAMPLES,        0,
-        None
-    };
-    XVisualInfo* visualInfo = glXChooseVisual(window_data_x11->display, window_data_x11->screen, glxAttribs);
-    if (visualInfo == 0) {
-        fprintf(stderr, "Could not create correct visual window.\n");
-        XCloseDisplay(window_data_x11->display);
         return false;
-    }
 
     window_data_x11->context = glXCreateContext(window_data_x11->display, visualInfo, NULL, GL_TRUE);
     glXMakeCurrent(window_data_x11->display, window_data_x11->window, window_data_x11->context);
@@ -120,6 +150,9 @@ create_GL_context(SWindowData *window_data) {
 
     init_GL(window_data);
 
+    SwapIntervalEXT = (PFNGLXSWAPINTERVALEXTPROC) getProcAddressGLX("glXSwapIntervalEXT");
+    set_target_fps_aux();
+
     return true;
 #endif
 }
@@ -289,4 +322,47 @@ redraw_GL(SWindowData *window_data, const void *pixels) {
 #endif
 }
 
+//-------------------------------------
+void
+set_target_fps_aux() {
+    // Assuming the monitor refresh rate is 60 hz
+    int interval = (int) ((60.0 * g_time_for_frame) + 0.5);
+
+#if defined(_WIN32) || defined(WIN32)
+
+    if (SwapIntervalEXT != 0x0) {
+        bool success = SwapIntervalEXT(interval);
+        if (GetSwapIntervalEXT != 0x0) {
+            int currentInterval = GetSwapIntervalEXT();
+            if (interval != currentInterval) {
+                fprintf(stderr, "Cannot set target swap interval. Current swap interval is %d\n", currentInterval);
+            }
+        }
+        else if (success == false) {
+            fprintf(stderr, "Cannot set target swap interval.\n");
+        }
+        g_use_hardware_sync = true;
+    }
+
+#elif defined(linux)
+    #define kGLX_SWAP_INTERVAL_EXT               0x20F1
+    #define kGLX_MAX_SWAP_INTERVAL_EXT           0x20F2
+
+    if (SwapIntervalEXT != 0x0) {
+        Display         *dpy     = glXGetCurrentDisplay();
+        GLXDrawable     drawable = glXGetCurrentDrawable();
+        unsigned int    currentInterval, maxInterval;
+
+        SwapIntervalEXT(dpy, drawable, interval);
+        glXQueryDrawable(dpy, drawable, kGLX_SWAP_INTERVAL_EXT, &currentInterval);
+        if (interval != currentInterval) {
+            glXQueryDrawable(dpy, drawable, kGLX_MAX_SWAP_INTERVAL_EXT, &maxInterval);
+            fprintf(stderr, "Cannot set target swap interval. Current swap interval is %d (max: %d)\n", currentInterval, maxInterval);
+        }
+        g_use_hardware_sync = true;
+    }
+
+#endif
+}
+
 #endif

src/windows/WinMiniFB.c

@@ -192,7 +192,7 @@ WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam) {
             if(mfb_EnableNonClientDpiScaling)
                 mfb_EnableNonClientDpiScaling(hWnd);
 
-            return DefWindowProc(hWnd, message, wParam, lParam);;
+            return DefWindowProc(hWnd, message, wParam, lParam);
         }
 
         // TODO
@@ -647,11 +647,10 @@ mfb_update_events(struct mfb_window *window) {
 ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 
 extern double   g_time_for_frame;
+extern bool     g_use_hardware_sync;
 
 bool
 mfb_wait_sync(struct mfb_window *window) {
-    MSG msg;
-
     if (window == 0x0) {
         return false;
     }
@@ -662,6 +661,11 @@ mfb_wait_sync(struct mfb_window *window) {
         return false;
     }
 
+    if(g_use_hardware_sync) {
+        return true;
+    }
+
+    MSG             msg;
     SWindowData_Win *window_data_win = (SWindowData_Win *) window_data->specific;
     double          current;
     uint32_t        millis = 1;

src/x11/X11MiniFB.c

@@ -433,6 +433,7 @@ mfb_update_events(struct mfb_window *window) {
 ///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
 
 extern double   g_time_for_frame;
+extern bool     g_use_hardware_sync;
 
 bool
 mfb_wait_sync(struct mfb_window *window) {
@@ -446,6 +447,10 @@ mfb_wait_sync(struct mfb_window *window) {
         return false;
     }
 
+    if(g_use_hardware_sync) {
+        return true;
+    }
+
     SWindowData_X11 *window_data_x11 = (SWindowData_X11 *) window_data->specific;
     XFlush(window_data_x11->display);
     XEvent      event;