Added GLFW_DOUBLEBUFFER.

README.md

@@ -61,6 +61,7 @@ GLFW bundles a number of dependencies in the `deps/` directory.
  - Added `GLFW_AUTO_ICONIFY` for controlling whether full screen windows
    automatically iconify (and restore the previous video mode) on focus loss
  - Added `GLFW_DONT_CARE` for indicating that any value is acceptable
+ - Added `GLFW_DOUBLEBUFFER` for controlling whether to use double buffering
  - Added `GLFW_INCLUDE_ES31` for including the OpenGL ES 3.1 header
  - Added *partial and experimental* support for Wayland
  - Bugfix: The debug context attribute was set from `GL_ARB_debug_output` even

docs/quick.dox

@@ -250,7 +250,7 @@ double time = glfwGetTime();
 
 @section quick_swap_buffers Swapping buffers
 
-GLFW windows always use double-buffering.  That means that you have two
+GLFW windows by default use double buffering.  That means that you have two
 rendering buffers; a front buffer and a back buffer.  The front buffer is the
 one being displayed and the back buffer the one you render to.
 

docs/window.dox

@@ -93,6 +93,7 @@ find out the actual attributes of the created window and context, use the
 
 The following hints are hard constraints:
 - `GLFW_STEREO`
+- `GLFW_DOUBLEBUFFER`
 - `GLFW_CLIENT_API`
 
 The following additional hints are hard constraints if requesting an OpenGL
@@ -137,7 +138,8 @@ application has no preference.
 The `GLFW_AUX_BUFFERS` hint specifies the desired number of auxiliary
 buffers.  `GLFW_DONT_CARE` means the application has no preference.
 
-The `GLFW_STEREO` hint specifies whether to use stereoscopic rendering.
+The `GLFW_STEREO` hint specifies whether to use stereoscopic rendering.  This is
+a hard constraint.
 
 The `GLFW_SAMPLES` hint specifies the desired number of samples to use for
 multisampling.  Zero disables multisampling.  `GLFW_DONT_CARE` means the
@@ -146,6 +148,10 @@ application has no preference.
 The `GLFW_SRGB_CAPABLE` hint specifies whether the framebuffer should be
 sRGB capable.
 
+The `GLFW_DOUBLEBUFFER` hint specifies whether the framebuffer should be double
+buffered.  You nearly always want to use double buffering.  This is a hard
+constraint.
+
 The `GLFW_REFRESH_RATE` hint specifies the desired refresh rate for full screen
 windows.  If set to zero, the highest available refresh rate will be used.  This
 hint is ignored for windowed mode windows.
@@ -154,7 +160,8 @@ hint is ignored for windowed mode windows.
 @subsection window_hints_ctx Context related hints
 
 The `GLFW_CLIENT_API` hint specifies which client API to create the context
-for.  Possible values are `GLFW_OPENGL_API` and `GLFW_OPENGL_ES_API`.
+for.  Possible values are `GLFW_OPENGL_API` and `GLFW_OPENGL_ES_API`.  This is
+a hard constraint.
 
 The `GLFW_CONTEXT_VERSION_MAJOR` and `GLFW_CONTEXT_VERSION_MINOR` hints
 specify the client API version that the created context must be compatible
@@ -219,6 +226,7 @@ a robustness strategy.
 | `GLFW_REFRESH_RATE`          | 0                         | 0 to `INT_MAX` or `GLFW_DONT_CARE` |
 | `GLFW_STEREO`                | `GL_FALSE`                | `GL_TRUE` or `GL_FALSE` |
 | `GLFW_SRGB_CAPABLE`          | `GL_FALSE`                | `GL_TRUE` or `GL_FALSE` |
+| `GLFW_DOUBLEBUFFER`          | `GL_TRUE`                 | `GL_TRUE` or `GL_FALSE` |
 | `GLFW_CLIENT_API`            | `GLFW_OPENGL_API`         | `GLFW_OPENGL_API` or `GLFW_OPENGL_ES_API` |
 | `GLFW_CONTEXT_VERSION_MAJOR` | 1                         | Any valid major version number of the chosen client API |
 | `GLFW_CONTEXT_VERSION_MINOR` | 0                         | Any valid minor version number of the chosen client API |
@@ -468,7 +476,7 @@ used by the context.  This is `GLFW_LOSE_CONTEXT_ON_RESET` or
 
 @section window_swap Swapping buffers
 
-GLFW windows are always double buffered.  That means that you have two
+GLFW windows are by default double buffered.  That means that you have two
 rendering buffers; a front buffer and a back buffer.  The front buffer is
 the one being displayed and the back buffer the one you render to.
 

include/GLFW/glfw3.h

@@ -514,6 +514,7 @@ extern "C" {
 #define GLFW_SAMPLES                0x0002100D
 #define GLFW_SRGB_CAPABLE           0x0002100E
 #define GLFW_REFRESH_RATE           0x0002100F
+#define GLFW_DOUBLEBUFFER           0x00021010
 
 #define GLFW_CLIENT_API             0x00022001
 #define GLFW_CONTEXT_VERSION_MAJOR  0x00022002

src/context.c

@@ -222,6 +222,12 @@ const _GLFWfbconfig* _glfwChooseFBConfig(const _GLFWfbconfig* desired,
             continue;
         }
 
+        if (desired->doublebuffer != current->doublebuffer)
+        {
+            // Double buffering is a hard constraint
+            continue;
+        }
+
         // Count number of missing buffers
         {
             missing = 0;

src/glx_context.c

@@ -85,10 +85,9 @@ static GLboolean chooseFBConfig(const _GLFWfbconfig* desired, GLXFBConfig* resul
         const GLXFBConfig n = nativeConfigs[i];
         _GLFWfbconfig* u = usableConfigs + usableCount;
 
-        if (!getFBConfigAttrib(n, GLX_DOUBLEBUFFER) ||
+        if (!getFBConfigAttrib(n, GLX_VISUAL_ID))
-            !getFBConfigAttrib(n, GLX_VISUAL_ID))
         {
-            // Only consider double-buffered GLXFBConfigs with associated visuals
+            // Only consider GLXFBConfigs with associated visuals
             continue;
         }
 
@@ -121,7 +120,11 @@ static GLboolean chooseFBConfig(const _GLFWfbconfig* desired, GLXFBConfig* resul
         u->accumAlphaBits = getFBConfigAttrib(n, GLX_ACCUM_ALPHA_SIZE);
 
         u->auxBuffers = getFBConfigAttrib(n, GLX_AUX_BUFFERS);
-        u->stereo = getFBConfigAttrib(n, GLX_STEREO);
+
+        if (getFBConfigAttrib(n, GLX_STEREO))
+            u->stereo = GL_TRUE;
+        if (getFBConfigAttrib(n, GLX_DOUBLEBUFFER))
+            u->doublebuffer = GL_TRUE;
 
         if (_glfw.glx.ARB_multisample)
             u->samples = getFBConfigAttrib(n, GLX_SAMPLES);

src/internal.h

@@ -200,6 +200,7 @@ struct _GLFWfbconfig
     int         stereo;
     int         samples;
     int         sRGB;
+    int         doublebuffer;
 
     // This is defined in the context API's context.h
     _GLFW_PLATFORM_FBCONFIG;
@@ -325,6 +326,7 @@ struct _GLFWlibrary
         int         samples;
         int         sRGB;
         int         refreshRate;
+        int         doublebuffer;
         int         api;
         int         major;
         int         minor;

src/nsgl_context.m

@@ -127,7 +127,6 @@ int _glfwCreateContext(_GLFWwindow* window,
     // Arbitrary array size here
     NSOpenGLPixelFormatAttribute attributes[40];
 
-    ADD_ATTR(NSOpenGLPFADoubleBuffer);
     ADD_ATTR(NSOpenGLPFAClosestPolicy);
 
 #if MAC_OS_X_VERSION_MAX_ALLOWED >= 1070
@@ -180,6 +179,9 @@ int _glfwCreateContext(_GLFWwindow* window,
     if (fbconfig->stereo)
         ADD_ATTR(NSOpenGLPFAStereo);
 
+    if (fbconfig->doublebuffer)
+        ADD_ATTR(NSOpenGLPFADoubleBuffer);
+
     if (fbconfig->samples != GLFW_DONT_CARE)
     {
         if (fbconfig->samples == 0)

src/wgl_context.c

@@ -181,8 +181,7 @@ static GLboolean choosePixelFormat(_GLFWwindow* window,
         {
             // Get pixel format attributes through WGL_ARB_pixel_format
             if (!getPixelFormatAttrib(window, n, WGL_SUPPORT_OPENGL_ARB) ||
-                !getPixelFormatAttrib(window, n, WGL_DRAW_TO_WINDOW_ARB) ||
+                !getPixelFormatAttrib(window, n, WGL_DRAW_TO_WINDOW_ARB))
-                !getPixelFormatAttrib(window, n, WGL_DOUBLE_BUFFER_ARB))
             {
                 continue;
             }
@@ -213,13 +212,20 @@ static GLboolean choosePixelFormat(_GLFWwindow* window,
             u->accumAlphaBits = getPixelFormatAttrib(window, n, WGL_ACCUM_ALPHA_BITS_ARB);
 
             u->auxBuffers = getPixelFormatAttrib(window, n, WGL_AUX_BUFFERS_ARB);
-            u->stereo = getPixelFormatAttrib(window, n, WGL_STEREO_ARB);
+
+            if (getPixelFormatAttrib(window, n, WGL_STEREO_ARB))
+                u->stereo = GL_TRUE;
+            if (getPixelFormatAttrib(window, n, WGL_DOUBLE_BUFFER_ARB))
+                u->doublebuffer = GL_TRUE;
 
             if (window->wgl.ARB_multisample)
                 u->samples = getPixelFormatAttrib(window, n, WGL_SAMPLES_ARB);
 
             if (window->wgl.ARB_framebuffer_sRGB)
-                u->sRGB = getPixelFormatAttrib(window, n, WGL_FRAMEBUFFER_SRGB_CAPABLE_ARB);
+            {
+                if (getPixelFormatAttrib(window, n, WGL_FRAMEBUFFER_SRGB_CAPABLE_ARB))
+                    u->sRGB = GL_TRUE;
+            }
         }
         else
         {
@@ -236,8 +242,7 @@ static GLboolean choosePixelFormat(_GLFWwindow* window,
             }
 
             if (!(pfd.dwFlags & PFD_DRAW_TO_WINDOW) ||
-                !(pfd.dwFlags & PFD_SUPPORT_OPENGL) ||
+                !(pfd.dwFlags & PFD_SUPPORT_OPENGL))
-                !(pfd.dwFlags & PFD_DOUBLEBUFFER))
             {
                 continue;
             }
@@ -265,7 +270,11 @@ static GLboolean choosePixelFormat(_GLFWwindow* window,
             u->accumAlphaBits = pfd.cAccumAlphaBits;
 
             u->auxBuffers = pfd.cAuxBuffers;
-            u->stereo = (pfd.dwFlags & PFD_STEREO) ? GL_TRUE : GL_FALSE;
+
+            if (pfd.dwFlags & PFD_STEREO)
+                u->stereo = GL_TRUE;
+            if (pfd.dwFlags & PFD_DOUBLEBUFFER)
+                u->doublebuffer = GL_TRUE;
         }
 
         u->wgl = n;

src/window.c

@@ -157,6 +157,7 @@ GLFWAPI GLFWwindow* glfwCreateWindow(int width, int height,
     fbconfig.stereo         = _glfw.hints.stereo;
     fbconfig.samples        = _glfw.hints.samples;
     fbconfig.sRGB           = _glfw.hints.sRGB;
+    fbconfig.doublebuffer   = _glfw.hints.doublebuffer ? GL_TRUE : GL_FALSE;
 
     // Set up desired window config
     wndconfig.width         = width;
@@ -266,13 +267,15 @@ void glfwDefaultWindowHints(void)
     _glfw.hints.decorated   = GL_TRUE;
     _glfw.hints.autoIconify = GL_TRUE;
 
-    // The default is 24 bits of color, 24 bits of depth and 8 bits of stencil
+    // The default is 24 bits of color, 24 bits of depth and 8 bits of stencil,
-    _glfw.hints.redBits     = 8;
+    // double buffered
-    _glfw.hints.greenBits   = 8;
+    _glfw.hints.redBits      = 8;
-    _glfw.hints.blueBits    = 8;
+    _glfw.hints.greenBits    = 8;
-    _glfw.hints.alphaBits   = 8;
+    _glfw.hints.blueBits     = 8;
-    _glfw.hints.depthBits   = 24;
+    _glfw.hints.alphaBits    = 8;
-    _glfw.hints.stencilBits = 8;
+    _glfw.hints.depthBits    = 24;
+    _glfw.hints.stencilBits  = 8;
+    _glfw.hints.doublebuffer = GL_TRUE;
 }
 
 GLFWAPI void glfwWindowHint(int target, int hint)
@@ -320,6 +323,9 @@ GLFWAPI void glfwWindowHint(int target, int hint)
         case GLFW_REFRESH_RATE:
             _glfw.hints.refreshRate = hint;
             break;
+        case GLFW_DOUBLEBUFFER:
+            _glfw.hints.doublebuffer = hint;
+            break;
         case GLFW_RESIZABLE:
             _glfw.hints.resizable = hint;
             break;