User Contexts API with Win32 implementation.

include/GLFW/glfw3.h

@@ -1276,6 +1276,18 @@ typedef struct GLFWmonitor GLFWmonitor;
  */
 typedef struct GLFWwindow GLFWwindow;
 
+/*! @brief Opaque user OpenGL context object.
+ *
+ *  Opaque user OpenGL context object.
+ *
+ *  @see @ref user_gl_context
+ *
+ *  @since Added in version 3.3.
+ *
+ *  @ingroup window
+ */
+typedef struct GLFWusercontext GLFWusercontext;
+
 /*! @brief Opaque cursor object.
  *
  *  Opaque cursor object.
@@ -5772,6 +5784,21 @@ GLFWAPI int glfwExtensionSupported(const char* extension);
  */
 GLFWAPI GLFWglproc glfwGetProcAddress(const char* procname);
 
+/*! @brief Create a new OpenGL user context for a window
+*
+*/ 
+GLFWAPI GLFWusercontext* glfwCreateUserContext(GLFWwindow* window);
+
+/*! @brief Delete an OpenGL user context
+*
+*/
+GLFWAPI void glfwDestroyUserContext(GLFWusercontext* context);
+
+/*! @brief Make an OpenGL user context
+*
+*/
+GLFWAPI void glfwMakeUserContextCurrent(GLFWusercontext* context);
+
 /*! @brief Returns whether the Vulkan loader and an ICD have been found.
  *
  *  This function returns whether the Vulkan loader and any minimally functional

src/context.c

@@ -758,3 +758,26 @@ GLFWAPI GLFWglproc glfwGetProcAddress(const char* procname)
     return window->context.getProcAddress(procname);
 }
 
+GLFWAPI GLFWusercontext* glfwCreateUserContext(GLFWwindow* handle)
+{
+    _GLFWusercontext* context;
+    _GLFWwindow* window = (_GLFWwindow*)handle;
+
+    context = _glfwPlatformCreateUserContext(window);
+
+    return (GLFWusercontext*)context;
+}
+
+GLFWAPI void glfwDestroyUserContext(GLFWusercontext* handle)
+{
+    _GLFWusercontext* context = (_GLFWusercontext*)handle;
+
+    _glfwPlatformDestroyUserContext(context);
+}
+
+GLFWAPI void glfwMakeUserContextCurrent(GLFWusercontext* handle)
+{
+    _GLFWusercontext* context = (_GLFWusercontext*)handle;
+
+    _glfwPlatformMakeUserContextCurrent(context);
+}

src/internal.h

@@ -75,6 +75,7 @@ typedef struct _GLFWmapping     _GLFWmapping;
 typedef struct _GLFWjoystick    _GLFWjoystick;
 typedef struct _GLFWtls         _GLFWtls;
 typedef struct _GLFWmutex       _GLFWmutex;
+typedef struct _GLFWusercontext _GLFWusercontext;
 
 typedef void (* _GLFWmakecontextcurrentfun)(_GLFWwindow*);
 typedef void (* _GLFWswapbuffersfun)(_GLFWwindow*);
@@ -681,6 +682,11 @@ void _glfwPlatformWaitEvents(void);
 void _glfwPlatformWaitEventsTimeout(double timeout);
 void _glfwPlatformPostEmptyEvent(void);
 
+_GLFWusercontext* _glfwPlatformCreateUserContext(_GLFWwindow* window);
+void _glfwPlatformDestroyUserContext(_GLFWusercontext* context);
+void _glfwPlatformMakeUserContextCurrent(_GLFWusercontext* context);
+
+
 void _glfwPlatformGetRequiredInstanceExtensions(char** extensions);
 int _glfwPlatformGetPhysicalDevicePresentationSupport(VkInstance instance,
                                                       VkPhysicalDevice device,

src/wgl_context.c

@@ -776,6 +776,62 @@ GLFWbool _glfwCreateContextWGL(_GLFWwindow* window,
 #undef setAttrib
 
 
+//////////////////////////////////////////////////////////////////////////
+//////                       GLFW platform API                      //////
+//////////////////////////////////////////////////////////////////////////
+
+_GLFWusercontext* _glfwPlatformCreateUserContext(_GLFWwindow* window)
+{
+    _GLFWusercontext* context;
+    context = calloc(1, sizeof(_GLFWusercontext));
+
+    context->handle = wglCreateContext(window->context.wgl.dc);
+    context->window = window;
+    if (!context->handle)
+    {
+        _glfwInputErrorWin32(GLFW_VERSION_UNAVAILABLE,
+                                "WGL: Failed to create user OpenGL context");
+        free(context);
+        return GLFW_FALSE;
+    }
+
+    if (!wglShareLists(window->context.wgl.handle,context->handle))
+    {
+        _glfwInputErrorWin32(GLFW_PLATFORM_ERROR,
+                                "WGL: Failed to enable sharing with window OpenGL context and user context");
+        free(context);
+        return GLFW_FALSE;
+    }
+    return context;
+}
+
+void _glfwPlatformDestroyUserContext(_GLFWusercontext* context)
+{
+    wglDeleteContext(context->handle);
+    free(context);
+}
+
+void _glfwPlatformMakeUserContextCurrent(_GLFWusercontext* context)
+{
+    if(context)
+    {
+        if(!wglMakeCurrent(context->window->context.wgl.dc,context->handle))
+        {
+            _glfwInputErrorWin32(GLFW_PLATFORM_ERROR,
+                                 "WGL: Failed to set current user context");
+        }
+    }
+    else
+    {
+        if (!wglMakeCurrent(NULL, NULL))
+        {
+            _glfwInputErrorWin32(GLFW_PLATFORM_ERROR,
+                                 "WGL: Failed to clear current context");
+        }
+    }
+}
+
+
 //////////////////////////////////////////////////////////////////////////
 //////                        GLFW native API                       //////
 //////////////////////////////////////////////////////////////////////////

src/wgl_context.h

@@ -151,6 +151,11 @@ typedef struct _GLFWlibraryWGL
 
 } _GLFWlibraryWGL;
 
+typedef struct _GLFWusercontext
+{
+    _GLFWwindow* window;
+    HGLRC        handle;
+} _GLFWusercontext;
 
 GLFWbool _glfwInitWGL(void);
 void _glfwTerminateWGL(void);

tests/CMakeLists.txt

@@ -28,6 +28,7 @@ add_executable(iconify iconify.c ${GETOPT} ${GLAD_GL})
 add_executable(monitors monitors.c ${GETOPT} ${GLAD_GL})
 add_executable(reopen reopen.c ${GLAD_GL})
 add_executable(cursor cursor.c ${GLAD_GL})
+add_executable(usercontext usercontext.c  ${GLAD_GL})
 
 add_executable(empty WIN32 MACOSX_BUNDLE empty.c ${TINYCTHREAD} ${GLAD_GL})
 add_executable(gamma WIN32 MACOSX_BUNDLE gamma.c ${GLAD_GL})
@@ -52,7 +53,7 @@ endif()
 set(GUI_ONLY_BINARIES empty gamma icon inputlag joysticks opacity tearing
     threads timeout title triangle-vulkan windows)
 set(CONSOLE_BINARIES clipboard events msaa glfwinfo iconify monitors reopen
-                     cursor)
+                     cursor usercontext)
 
 set_target_properties(${GUI_ONLY_BINARIES} ${CONSOLE_BINARIES} PROPERTIES
                       C_STANDARD 99

tests/usercontext.c

@@ -0,0 +1,60 @@
+#include <glad/gl.h>
+#include <GLFW/glfw3.h>
+
+int main(void)
+{
+    GLFWwindow* window;
+    GLFWusercontext* usercontext;
+
+    /* Initialize the library */
+    if (!glfwInit())
+        return -1;
+
+    /* Create a windowed mode window and its OpenGL context */
+    window = glfwCreateWindow(640, 480, "User Context", NULL, NULL);
+    if (!window)
+    {
+        glfwTerminate();
+        return -1;
+    }
+
+    /* Make the window's context current */
+    glfwMakeContextCurrent(window);
+    gladLoadGL(glfwGetProcAddress);
+
+    /* make a new context */
+    usercontext = glfwCreateUserContext(window);
+    if (!usercontext)
+    {
+        glfwTerminate();
+        return -1;
+    }
+
+    /* set the user context current */
+    glfwMakeContextCurrent(NULL);
+    glfwMakeUserContextCurrent(usercontext);
+
+    /* set the window context current */
+    glfwMakeUserContextCurrent(NULL);
+    glfwMakeContextCurrent(window);
+
+    glClearColor( 0.4f, 0.3f, 0.4f, 0.0f );
+
+
+    /* Loop until the user closes the window */
+    while (!glfwWindowShouldClose(window))
+    {
+        /* Render here */
+        glClear(GL_COLOR_BUFFER_BIT);
+
+        /* Swap front and back buffers */
+        glfwSwapBuffers(window);
+
+        /* Poll for and process events */
+        glfwPollEvents();
+    }
+
+    glfwDestroyUserContext(usercontext);
+    glfwTerminate();
+    return 0;
+}