Made context creation backends more consistent.

src/egl_context.c

@@ -236,7 +236,7 @@ void _glfwTerminateContextAPI(void)
     assert((size_t) index < sizeof(attribs) / sizeof(attribs[0])); \
 }
 
-// Prepare for creation of the OpenGL context
+// Create the OpenGL or OpenGL ES context
 //
 int _glfwCreateContext(_GLFWwindow* window,
                        const _GLFWctxconfig* ctxconfig,
@@ -296,8 +296,7 @@ int _glfwCreateContext(_GLFWwindow* window,
 
         window->egl.visual = XGetVisualInfo(_glfw.x11.display,
                                             mask, &info, &count);
-
-        if (window->egl.visual == NULL)
+        if (!window->egl.visual)
         {
             _glfwInputError(GLFW_PLATFORM_ERROR,
                             "EGL: Failed to retrieve visual for EGLConfig");
@@ -345,7 +344,7 @@ int _glfwCreateContext(_GLFWwindow* window,
                 flags |= EGL_CONTEXT_OPENGL_DEBUG_BIT_KHR;
         }
 
-        if (ctxconfig->robustness != GLFW_NO_ROBUSTNESS)
+        if (ctxconfig->robustness)
         {
             if (ctxconfig->robustness == GLFW_NO_RESET_NOTIFICATION)
                 strategy = EGL_NO_RESET_NOTIFICATION_KHR;

src/glx_context.c

@@ -281,7 +281,7 @@ void _glfwTerminateContextAPI(void)
     assert((size_t) index < sizeof(attribs) / sizeof(attribs[0])); \
 }
 
-// Prepare for creation of the OpenGL context
+// Create the OpenGL or OpenGL ES context
 //
 int _glfwCreateContext(_GLFWwindow* window,
                        const _GLFWctxconfig* ctxconfig,
@@ -303,8 +303,7 @@ int _glfwCreateContext(_GLFWwindow* window,
 
     // Retrieve the corresponding visual
     window->glx.visual = glXGetVisualFromFBConfig(_glfw.x11.display, native);
-
-    if (window->glx.visual == NULL)
+    if (!window->glx.visual)
     {
         _glfwInputError(GLFW_PLATFORM_ERROR,
                         "GLX: Failed to retrieve visual for GLXFBConfig");
@@ -372,7 +371,7 @@ int _glfwCreateContext(_GLFWwindow* window,
         else
             mask |= GLX_CONTEXT_ES2_PROFILE_BIT_EXT;
 
-        if (ctxconfig->robustness != GLFW_NO_ROBUSTNESS)
+        if (ctxconfig->robustness)
         {
             if (_glfw.glx.ARB_create_context_robustness)
             {
@@ -413,7 +412,7 @@ int _glfwCreateContext(_GLFWwindow* window,
                                               True,
                                               attribs);
 
-        if (window->glx.context == NULL)
+        if (!window->glx.context)
         {
             // HACK: This is a fallback for the broken Mesa implementation of
             //       GLX_ARB_create_context_profile, which fails default 1.0
@@ -433,7 +432,7 @@ int _glfwCreateContext(_GLFWwindow* window,
 
     _glfwReleaseXErrorHandler();
 
-    if (window->glx.context == NULL)
+    if (!window->glx.context)
     {
         _glfwInputXError(GLFW_PLATFORM_ERROR, "GLX: Failed to create context");
         return GL_FALSE;

src/nsgl_context.m

@@ -112,14 +112,8 @@ int _glfwCreateContext(_GLFWwindow* window,
     }
 #endif /*MAC_OS_X_VERSION_MAX_ALLOWED*/
 
-    // Fail if a robustness strategy was requested
-    if (ctxconfig->robustness)
-    {
-        _glfwInputError(GLFW_VERSION_UNAVAILABLE,
-                        "NSGL: OS X does not support OpenGL robustness "
-                        "strategies");
-        return GL_FALSE;
-    }
+    // Context robustness modes (GL_KHR_robustness) 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

@@ -345,7 +345,7 @@ void _glfwTerminateContextAPI(void)
     assert((size_t) index < sizeof(attribs) / sizeof(attribs[0])); \
 }
 
-// Prepare for creation of the OpenGL context
+// Create the OpenGL or OpenGL ES context
 //
 int _glfwCreateContext(_GLFWwindow* window,
                        const _GLFWctxconfig* ctxconfig,
@@ -423,6 +423,10 @@ int _glfwCreateContext(_GLFWwindow* window,
 
         if (ctxconfig->major != 1 || ctxconfig->minor != 0)
         {
+            // NOTE: Only request an explicitly versioned context when
+            //       necessary, as explicitly requesting version 1.0 does not
+            //       always return the highest available version
+
             setWGLattrib(WGL_CONTEXT_MAJOR_VERSION_ARB, ctxconfig->major);
             setWGLattrib(WGL_CONTEXT_MINOR_VERSION_ARB, ctxconfig->minor);
         }