Support OpenGL mode external windows through an SDL hack, needs choosing the pixel format manually.

Engine/Graphics/OpenGL/OGLGraphics.cpp

@@ -236,96 +236,101 @@ bool Graphics::SetMode(int width, int height, bool fullscreen, bool vsync, bool
         }
     }
     
-    // Close the existing window and OpenGL context, mark GPU objects as lost
-    Release(false, true);
-    
+    // With an external window, only the size can change after initial setup, so do not recreate context
+    if (!externalWindow_ || !impl_->context_)
     {
-        // SDL window parameters are static, so need to operate under static lock
-        MutexLock lock(GetStaticMutex());
-        
-        #ifdef IOS
-        SDL_SetHint(SDL_HINT_ORIENTATIONS, "LandscapeLeft LandscapeRight");
-        #endif
-        
-        SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
-        SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
-        SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 8);
-        SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 8);
-        SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, 8);
-        SDL_GL_SetAttribute(SDL_GL_ALPHA_SIZE, 0);
-        #ifndef GL_ES_VERSION_2_0
-        SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 8);
-        #else
-        SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 0);
-        #endif
-        SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 2);
-        SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);
-        
-        if (multiSample > 1)
-        {
-            SDL_GL_SetAttribute(SDL_GL_MULTISAMPLEBUFFERS, 1);
-            SDL_GL_SetAttribute(SDL_GL_MULTISAMPLESAMPLES, multiSample);
-        }
-        else
-        {
-            SDL_GL_SetAttribute(SDL_GL_MULTISAMPLEBUFFERS, 0);
-            SDL_GL_SetAttribute(SDL_GL_MULTISAMPLESAMPLES, 0);
-        }
-        
-        unsigned flags = SDL_WINDOW_OPENGL | SDL_WINDOW_SHOWN;
-        int x = fullscreen ? 0 : SDL_WINDOWPOS_UNDEFINED;
-        int y = fullscreen ? 0 : SDL_WINDOWPOS_UNDEFINED;
-        if (fullscreen)
-            flags |= SDL_WINDOW_FULLSCREEN | SDL_WINDOW_BORDERLESS;
-        
-        if (!externalWindow_)
-            impl_->window_ = SDL_CreateWindow(windowTitle_.CString(), x, y, width, height, flags);
-        else
-        {
-            impl_->window_ = SDL_CreateWindowFrom(externalWindow_);
-            fullscreen = false;
-        }
-        if (!impl_->window_)
-        {
-            LOGERROR("Could not open window");
-            return false;
-        }
-        
-        // Create/restore context and GPU objects and set initial renderstate
-        Restore();
-        
-        if (!impl_->context_)
+        // Close the existing window and OpenGL context, mark GPU objects as lost
+        Release(false, true);
+    
         {
-            LOGERROR("Could not create OpenGL context");
-            return false;
-        }
-        
-        // If OpenGL extensions not yet initialized, initialize now
-        #ifndef GL_ES_VERSION_2_0
-        if (!GLeeInitialized())
-            GLeeInit();
+            // SDL window parameters are static, so need to operate under static lock
+            MutexLock lock(GetStaticMutex());
         
-        if (!_GLEE_VERSION_2_0)
-        {
-            LOGERROR("OpenGL 2.0 is required");
-            Release(true, true);
-            return false;
-        }
+            #ifdef IOS
+            SDL_SetHint(SDL_HINT_ORIENTATIONS, "LandscapeLeft LandscapeRight");
+            #endif
+            
+            SDL_GL_SetAttribute(SDL_GL_DOUBLEBUFFER, 1);
+            SDL_GL_SetAttribute(SDL_GL_DEPTH_SIZE, 24);
+            SDL_GL_SetAttribute(SDL_GL_RED_SIZE, 8);
+            SDL_GL_SetAttribute(SDL_GL_GREEN_SIZE, 8);
+            SDL_GL_SetAttribute(SDL_GL_BLUE_SIZE, 8);
+            SDL_GL_SetAttribute(SDL_GL_ALPHA_SIZE, 0);
+            #ifndef GL_ES_VERSION_2_0
+            SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 8);
+            #else
+            SDL_GL_SetAttribute(SDL_GL_STENCIL_SIZE, 0);
+            #endif
+            SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 2);
+            SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 0);
+            
+            if (multiSample > 1)
+            {
+                SDL_GL_SetAttribute(SDL_GL_MULTISAMPLEBUFFERS, 1);
+                SDL_GL_SetAttribute(SDL_GL_MULTISAMPLESAMPLES, multiSample);
+            }
+            else
+            {
+                SDL_GL_SetAttribute(SDL_GL_MULTISAMPLEBUFFERS, 0);
+                SDL_GL_SetAttribute(SDL_GL_MULTISAMPLESAMPLES, 0);
+            }
+            
+            unsigned flags = SDL_WINDOW_OPENGL | SDL_WINDOW_SHOWN;
+            int x = fullscreen ? 0 : SDL_WINDOWPOS_UNDEFINED;
+            int y = fullscreen ? 0 : SDL_WINDOWPOS_UNDEFINED;
+            if (fullscreen)
+                flags |= SDL_WINDOW_FULLSCREEN | SDL_WINDOW_BORDERLESS;
+            
+            if (!externalWindow_)
+                impl_->window_ = SDL_CreateWindow(windowTitle_.CString(), x, y, width, height, flags);
+            else
+            {
+                if (!impl_->window_)
+                    impl_->window_ = SDL_CreateWindowFrom(externalWindow_);
+                fullscreen = false;
+            }
+            if (!impl_->window_)
+            {
+                LOGERROR("Could not open window");
+                return false;
+            }
+            
+            // Create/restore context and GPU objects and set initial renderstate
+            Restore();
+            
+            if (!impl_->context_)
+            {
+                LOGERROR("Could not create OpenGL context");
+                return false;
+            }
+            
+            // If OpenGL extensions not yet initialized, initialize now
+            #ifndef GL_ES_VERSION_2_0
+            if (!GLeeInitialized())
+                GLeeInit();
+            
+            if (!_GLEE_VERSION_2_0)
+            {
+                LOGERROR("OpenGL 2.0 is required");
+                Release(true, true);
+                return false;
+            }
+            
+            if (!CheckExtension("EXT_framebuffer_object") || !CheckExtension("EXT_packed_depth_stencil"))
+            {
+                LOGERROR("EXT_framebuffer_object and EXT_packed_depth_stencil OpenGL extensions are required");
+                Release(true, true);
+                return false;
+            }
         
-        if (!CheckExtension("EXT_framebuffer_object") || !CheckExtension("EXT_packed_depth_stencil"))
-        {
-            LOGERROR("EXT_framebuffer_object and EXT_packed_depth_stencil OpenGL extensions are required");
-            Release(true, true);
-            return false;
+            dxtTextureSupport_ = CheckExtension("EXT_texture_compression_s3tc");
+            anisotropySupport_ = CheckExtension("EXT_texture_filter_anisotropic");
+            #else
+            dxtTextureSupport_ = CheckExtension("EXT_texture_compression_dxt1");
+            etcTextureSupport_ = CheckExtension("OES_compressed_ETC1_RGB8_texture");
+            pvrtcTextureSupport_ = CheckExtension("IMG_texture_compression_pvrtc");
+            #endif
         }
-        
-        dxtTextureSupport_ = CheckExtension("EXT_texture_compression_s3tc");
-        anisotropySupport_ = CheckExtension("EXT_texture_filter_anisotropic");
-        #else
-        dxtTextureSupport_ = CheckExtension("EXT_texture_compression_dxt1");
-        etcTextureSupport_ = CheckExtension("OES_compressed_ETC1_RGB8_texture");
-        pvrtcTextureSupport_ = CheckExtension("IMG_texture_compression_pvrtc");
-        #endif
     }
     
     // Set vsync
@@ -336,12 +341,13 @@ bool Graphics::SetMode(int width, int height, bool fullscreen, bool vsync, bool
     glGetIntegerv(GL_FRAMEBUFFER_BINDING, (GLint*)&impl_->systemFbo_);
     #endif
     
-    SDL_GetWindowSize(impl_->window_, &width_, &height_);
     fullscreen_ = fullscreen;
     vsync_ = vsync;
     tripleBuffer_ = tripleBuffer;
     multiSample_ = multiSample;
     
+    SDL_GetWindowSize(impl_->window_, &width_, &height_);
+    
     // Reset rendertargets and viewport for the new screen mode
     ResetRenderTargets();
     
@@ -1845,8 +1851,13 @@ void Graphics::Release(bool clearGPUObjects, bool closeWindow)
         MutexLock lock(GetStaticMutex());
         
         SDL_ShowCursor(SDL_TRUE);
-        SDL_DestroyWindow(impl_->window_);
-        impl_->window_ = 0;
+        
+        // Do not destroy external window except when shutting down
+        if (!externalWindow_ || clearGPUObjects)
+        {
+            SDL_DestroyWindow(impl_->window_);
+            impl_->window_ = 0;
+        }
     }
 }
 

ThirdParty/SDL/src/video/SDL_video.c

@@ -2511,9 +2511,22 @@ SDL_GL_CreateContext(SDL_Window * window)
     SDL_GLContext ctx = NULL;
     CHECK_WINDOW_MAGIC(window, NULL);
 
+    // Urho3D: set up OpenGL support dynamically if necessary for external windows
     if (!(window->flags & SDL_WINDOW_OPENGL)) {
+        #if (SDL_VIDEO_OPENGL && __MACOSX__) || __IPHONEOS__ || __ANDROID__
+            window->flags |= SDL_WINDOW_OPENGL;
+        #else
+            window->flags |= SDL_WINDOW_OPENGL;
+            if (!_this->GL_CreateContext) {
+                SDL_SetError("No OpenGL support in video driver");
+                return NULL;
+            }
+            SDL_GL_LoadLibrary(NULL);
+        #endif
+        /*
         SDL_SetError("The specified window isn't an OpenGL window");
         return NULL;
+        */
     }
 
     ctx = _this->GL_CreateContext(_this, window);