glfwSwapInterval(1) fails to enable vsync?

Question

glfwSwapInterval(1) doesn't seem to be working for me. If I force VSync in CCC or setVerticalSyncEnabled(true) in SFML my fps drops to 60, but GLFW just keeps running at 9000 fps. Am I going about this the wrong way or is GLFW bugged?

Solution 1

Well looks like GLFW doesn't want to turn VSync on when desktop compositing is enabled. If you want VSync anyway this will work on Windows:

#ifdef _WIN32
    // Turn on vertical screen sync under Windows.
    // (I.e. it uses the WGL_EXT_swap_control extension)
    typedef BOOL (WINAPI *PFNWGLSWAPINTERVALEXTPROC)(int interval);
    PFNWGLSWAPINTERVALEXTPROC wglSwapIntervalEXT = NULL;
    wglSwapIntervalEXT = (PFNWGLSWAPINTERVALEXTPROC)wglGetProcAddress("wglSwapIntervalEXT");
    if(wglSwapIntervalEXT)
        wglSwapIntervalEXT(1);
#endif

For other OSs google will help you.

Solution 2

Rebuild GLFW3 with the GLFW_USE_DWM_SWAP_INTERVAL option.

See glfw/src/config.h

The GLFW docs warn about jitter problems, but I don't see those myself.

Solution 3

Found that glfwSwapInterval needed calling again after changing between window and full screen mode, otherwise the framerate would be massive.

if (fullScreen)
            {
                glfwSetWindowMonitor(window, monitor, 0, 0, monitorMode->width, monitorMode->height, monitorMode->refreshRate);

                // Added to fix framerate to vertical refresh //
                glfwSwapInterval(1);
            }
            else
            {
                glfwSetWindowMonitor(window, NULL, 0, 0, monitorMode->width, monitorMode->height, monitorMode->refreshRate);
            }

Comments

[Bram]

This fix did not work on my Intel HD 4600, as the proc address was 0. But configuring GLFW3 to use GLFW_USE_DWM_SWAP_INTERVAL did.

[legends2k]

With release 3.1.2 this flag was removed; however, the fix is also in, so it isn't needed any longer :)