Added glfwPostEmptyEvent.

README.md

@@ -50,6 +50,8 @@ The following dependencies are needed by the examples and test programs:
  - Bugfix: The debug context attribute was set from `GL_ARB_debug_output` even
            when a debug context had not been requested
  - Bugfix: The particles example was not linked against the threading library
+ - Added `glfwPostEmptyEvent` for allowing secondary threads to cause
+   `glfwWaitEvents` to return
  - [Cocoa] Added `_GLFW_USE_RETINA` to control whether windows will use the full
            resolution on Retina displays
  - [Cocoa] Bugfix: Using a 1x1 cursor for hidden mode caused some screen

docs/news.dox

@@ -13,6 +13,13 @@ GLFW now provides a callback for receiving the paths of files dropped onto GLFW
 windows.  The callback is set with the @ref glfwSetDropCallback function.
 
 
+@subsection news_31_emptyevent Empty event support
+
+GLFW now provides the @ref glfwPostEmptyEvent function for posting an empty
+event from a secondary thread to the main thread event queue, causing @ref
+glfwWaitEvents to return.
+
+
 @section news_30 New features in version 3.0
 
 @subsection news_30_cmake CMake build system

include/GLFW/glfw3.h

@@ -1745,6 +1745,10 @@ GLFWAPI void glfwPollEvents(void);
  *  [window refresh callback](@ref GLFWwindowrefreshfun) to redraw the contents
  *  of your window when necessary during the operation.
  *
+ *  @remarks If no windows exist, this function returns immediately.  For
+ *  synchronization of threads in applications that do not create windows, use
+ *  your threading library of choice.
+ *
  *  @note This function may only be called from the main thread.
  *
  *  @note This function may not be called from a callback.
@@ -1758,6 +1762,23 @@ GLFWAPI void glfwPollEvents(void);
  */
 GLFWAPI void glfwWaitEvents(void);
 
+/*! @brief Posts an empty event to the event queue.
+ *
+ *  This function posts an empty event from the current thread to the main
+ *  thread event queue, causing @ref glfwWaitEvents to return.
+ *
+ *  @remarks If no windows exist, this function returns immediately.  For
+ *  synchronization of threads in applications that do not create windows, use
+ *  your threading library of choice.
+ *
+ *  @remarks This function may be called from secondary threads.
+ *
+ *  @sa glfwWaitEvents
+ *
+ *  @ingroup window
+ */
+GLFWAPI void glfwPostEmptyEvent(void);
+
 /*! @brief Returns the value of an input option for the specified window.
  *
  *  @param[in] window The window to query.

src/cocoa_window.m

@@ -1147,6 +1147,20 @@ void _glfwPlatformWaitEvents(void)
     _glfwPlatformPollEvents();
 }
 
+void _glfwPlatformPostEmptyEvent(void)
+{
+    NSEvent* event = [NSEvent otherEventWithType:NSApplicationDefined
+                                        location:NSMakePoint(0, 0)
+                                   modifierFlags:0
+                                       timestamp:0
+                                    windowNumber:0
+                                         context:nil
+                                         subtype:0
+                                           data1:0
+                                           data2:0];
+    [NSApp postEvent:event atStart:YES];
+}
+
 void _glfwPlatformSetCursorPos(_GLFWwindow* window, double x, double y)
 {
     setModeCursor(window);

src/internal.h

@@ -539,6 +539,11 @@ void _glfwPlatformPollEvents(void);
  */
 void _glfwPlatformWaitEvents(void);
 
+/*! @copydoc glfwPostEmptyEvent
+ *  @ingroup platform
+ */
+void _glfwPlatformPostEmptyEvent(void);
+
 /*! @copydoc glfwMakeContextCurrent
  *  @ingroup platform
  */

src/win32_window.c

@@ -1181,6 +1181,12 @@ void _glfwPlatformWaitEvents(void)
     _glfwPlatformPollEvents();
 }
 
+void _glfwPlatformPostEmptyEvent(void)
+{
+    _GLFWwindow* window = _glfw.windowListHead;
+    PostMessage(window->win32.handle, WM_NULL, 0, 0);
+}
+
 void _glfwPlatformSetCursorPos(_GLFWwindow* window, double xpos, double ypos)
 {
     POINT pos = { (int) xpos, (int) ypos };

src/window.c

@@ -669,6 +669,20 @@ GLFWAPI void glfwPollEvents(void)
 GLFWAPI void glfwWaitEvents(void)
 {
     _GLFW_REQUIRE_INIT();
+
+    if (!_glfw.windowListHead)
+        return;
+
     _glfwPlatformWaitEvents();
 }
 
+GLFWAPI void glfwPostEmptyEvent(void)
+{
+    _GLFW_REQUIRE_INIT();
+
+    if (!_glfw.windowListHead)
+        return;
+
+    _glfwPlatformPostEmptyEvent();
+}
+

src/x11_window.c

@@ -1305,6 +1305,21 @@ void _glfwPlatformWaitEvents(void)
     _glfwPlatformPollEvents();
 }
 
+void _glfwPlatformPostEmptyEvent(void)
+{
+    XEvent event;
+    _GLFWwindow* window = _glfw.windowListHead;
+
+    memset(&event, 0, sizeof(event));
+    event.type = ClientMessage;
+    event.xclient.window = window->x11.handle;
+    event.xclient.format = 32; // Data is 32-bit longs
+    event.xclient.message_type = _glfw.x11._NULL;
+
+    XSendEvent(_glfw.x11.display, window->x11.handle, False, 0, &event);
+    XFlush(_glfw.x11.display);
+}
+
 void _glfwPlatformSetCursorPos(_GLFWwindow* window, double x, double y)
 {
     // Store the new position so it can be recognized later