Added support for GL_KHR_context_flush_control.

src/context.c

@@ -198,6 +198,17 @@ GLboolean _glfwIsValidContextConfig(const _GLFWctxconfig* ctxconfig)
         }
     }
 
+    if (ctxconfig->release)
+    {
+        if (ctxconfig->release != GLFW_RELEASE_BEHAVIOR_NONE &&
+            ctxconfig->release != GLFW_RELEASE_BEHAVIOR_FLUSH)
+        {
+            _glfwInputError(GLFW_INVALID_VALUE,
+                            "Invalid context release behavior requested");
+            return GL_FALSE;
+        }
+    }
+
     return GL_TRUE;
 }
 
@@ -468,6 +479,17 @@ GLboolean _glfwRefreshContextAttribs(const _GLFWctxconfig* ctxconfig)
                 window->context.robustness = GLFW_NO_RESET_NOTIFICATION;
         }
     }
+
+    if (glfwExtensionSupported("GL_KHR_context_flush_control"))
+    {
+        GLint behavior;
+        glGetIntegerv(GL_CONTEXT_RELEASE_BEHAVIOR, &behavior);
+
+        if (behavior == GL_NONE)
+            window->context.release = GLFW_RELEASE_BEHAVIOR_NONE;
+        else if (behavior == GL_CONTEXT_RELEASE_BEHAVIOR_FLUSH)
+            window->context.release = GLFW_RELEASE_BEHAVIOR_FLUSH;
+    }
 #endif // _GLFW_USE_OPENGL
 
     return GL_TRUE;

src/egl_context.c

@@ -381,6 +381,9 @@ int _glfwCreateContext(_GLFWwindow* window,
         setEGLattrib(EGL_NONE, EGL_NONE);
     }
 
+    // Context release behaviors (GL_KHR_context_flush_control) are not yet
+    // supported on EGL but are not a hard constraint, so ignore and continue
+
     window->egl.context = eglCreateContext(_glfw.egl.display,
                                            config, share, attribs);
 

src/glx_context.c

@@ -255,6 +255,9 @@ int _glfwInitContextAPI(void)
     if (_glfwPlatformExtensionSupported("GLX_EXT_create_context_es2_profile"))
         _glfw.glx.EXT_create_context_es2_profile = GL_TRUE;
 
+    if (_glfwPlatformExtensionSupported("GLX_ARB_context_flush_control"))
+        _glfw.glx.ARB_context_flush_control = GL_TRUE;
+
     return GL_TRUE;
 }
 
@@ -384,6 +387,23 @@ int _glfwCreateContext(_GLFWwindow* window,
             }
         }
 
+        if (ctxconfig->release)
+        {
+            if (_glfw.glx.ARB_context_flush_control)
+            {
+                if (ctxconfig->release == GLFW_RELEASE_BEHAVIOR_NONE)
+                {
+                    setGLXattrib(GLX_CONTEXT_RELEASE_BEHAVIOR_ARB,
+                                 GLX_CONTEXT_RELEASE_BEHAVIOR_NONE_ARB);
+                }
+                else if (ctxconfig->release == GLFW_RELEASE_BEHAVIOR_FLUSH)
+                {
+                    setGLXattrib(GLX_CONTEXT_RELEASE_BEHAVIOR_ARB,
+                                 GLX_CONTEXT_RELEASE_BEHAVIOR_FLUSH_ARB);
+                }
+            }
+        }
+
         if (ctxconfig->major != 1 || ctxconfig->minor != 0)
         {
             // NOTE: Only request an explicitly versioned context when

src/glx_context.h

@@ -105,6 +105,7 @@ typedef struct _GLFWlibraryGLX
     GLboolean       ARB_create_context_profile;
     GLboolean       ARB_create_context_robustness;
     GLboolean       EXT_create_context_es2_profile;
+    GLboolean       ARB_context_flush_control;
 
 #if defined(_GLFW_DLOPEN_LIBGL)
     void*           libGL;  // dlopen handle for libGL.so

src/internal.h

@@ -173,6 +173,7 @@ struct _GLFWctxconfig
     GLboolean     debug;
     int           profile;
     int           robustness;
+    int           release;
     _GLFWwindow*  share;
 };
 
@@ -242,6 +243,7 @@ struct _GLFWwindow
         GLboolean       forward, debug;
         int             profile;
         int             robustness;
+        int             release;
     } context;
 
 #if defined(_GLFW_USE_OPENGL)
@@ -338,6 +340,7 @@ struct _GLFWlibrary
         int         debug;
         int         profile;
         int         robustness;
+        int         release;
     } hints;
 
     double          cursorPosX, cursorPosY;

src/nsgl_context.m

@@ -115,6 +115,9 @@ int _glfwCreateContext(_GLFWwindow* window,
     // Context robustness modes (GL_KHR_robustness) are not yet supported on
     // OS X but are not a hard constraint, so ignore and continue
 
+    // Context release behaviors (GL_KHR_context_flush_control) are not yet
+    // supported on OS X but are not a hard constraint, so ignore and continue
+
 #define ADD_ATTR(x) { attributes[attributeCount++] = x; }
 #define ADD_ATTR2(x, y) { ADD_ATTR(x); ADD_ATTR(y); }
 

src/wgl_context.c

@@ -57,6 +57,7 @@ static void initWGLExtensions(_GLFWwindow* window)
     window->wgl.ARB_create_context_robustness = GL_FALSE;
     window->wgl.EXT_swap_control = GL_FALSE;
     window->wgl.ARB_pixel_format = GL_FALSE;
+    window->wgl.ARB_context_flush_control = GL_FALSE;
 
     window->wgl.GetExtensionsStringEXT = (PFNWGLGETEXTENSIONSSTRINGEXTPROC)
         wglGetProcAddress("wglGetExtensionsStringEXT");
@@ -119,6 +120,9 @@ static void initWGLExtensions(_GLFWwindow* window)
         if (window->wgl.GetPixelFormatAttribivARB)
             window->wgl.ARB_pixel_format = GL_TRUE;
     }
+
+    if (_glfwPlatformExtensionSupported("WGL_ARB_context_flush_control"))
+        window->wgl.ARB_context_flush_control = GL_TRUE;
 }
 
 // Returns the specified attribute of the specified pixel format
@@ -421,6 +425,23 @@ int _glfwCreateContext(_GLFWwindow* window,
             }
         }
 
+        if (ctxconfig->release)
+        {
+            if (window->wgl.ARB_context_flush_control)
+            {
+                if (ctxconfig->release == GLFW_RELEASE_BEHAVIOR_NONE)
+                {
+                    setWGLattrib(WGL_CONTEXT_RELEASE_BEHAVIOR_ARB,
+                                 WGL_CONTEXT_RELEASE_BEHAVIOR_NONE_ARB);
+                }
+                else if (ctxconfig->release == GLFW_RELEASE_BEHAVIOR_FLUSH)
+                {
+                    setWGLattrib(WGL_CONTEXT_RELEASE_BEHAVIOR_ARB,
+                                 WGL_CONTEXT_RELEASE_BEHAVIOR_FLUSH_ARB);
+                }
+            }
+        }
+
         if (ctxconfig->major != 1 || ctxconfig->minor != 0)
         {
             // NOTE: Only request an explicitly versioned context when
@@ -535,6 +556,12 @@ int _glfwAnalyzeContext(const _GLFWwindow* window,
 
             required = GL_TRUE;
         }
+
+        if (ctxconfig->release)
+        {
+            if (window->wgl.ARB_context_flush_control)
+                required = GL_TRUE;
+        }
     }
     else
     {

src/wgl_context.h

@@ -65,6 +65,7 @@ typedef struct _GLFWcontextWGL
     GLboolean                           ARB_create_context_profile;
     GLboolean                           EXT_create_context_es2_profile;
     GLboolean                           ARB_create_context_robustness;
+    GLboolean                           ARB_context_flush_control;
 } _GLFWcontextWGL;
 
 

src/window.c

@@ -178,6 +178,7 @@ GLFWAPI GLFWwindow* glfwCreateWindow(int width, int height,
     ctxconfig.debug         = _glfw.hints.debug ? GL_TRUE : GL_FALSE;
     ctxconfig.profile       = _glfw.hints.profile;
     ctxconfig.robustness    = _glfw.hints.robustness;
+    ctxconfig.release       = _glfw.hints.release;
     ctxconfig.share         = (_GLFWwindow*) share;
 
     // Check the OpenGL bits of the window config
@@ -272,7 +273,7 @@ void glfwDefaultWindowHints(void)
     memset(&_glfw.hints, 0, sizeof(_glfw.hints));
 
     // The default is OpenGL with minimum version 1.0
-    _glfw.hints.api = GLFW_OPENGL_API;
+    _glfw.hints.api   = GLFW_OPENGL_API;
     _glfw.hints.major = 1;
     _glfw.hints.minor = 0;
 
@@ -383,6 +384,9 @@ GLFWAPI void glfwWindowHint(int target, int hint)
         case GLFW_OPENGL_PROFILE:
             _glfw.hints.profile = hint;
             break;
+        case GLFW_CONTEXT_RELEASE_BEHAVIOR:
+            _glfw.hints.release = hint;
+            break;
         default:
             _glfwInputError(GLFW_INVALID_ENUM, NULL);
             break;
@@ -623,6 +627,8 @@ GLFWAPI int glfwGetWindowAttrib(GLFWwindow* handle, int attrib)
             return window->context.debug;
         case GLFW_OPENGL_PROFILE:
             return window->context.profile;
+        case GLFW_CONTEXT_RELEASE_BEHAVIOR:
+            return window->context.release;
     }
 
     _glfwInputError(GLFW_INVALID_ENUM, NULL);