10 files changed, 63 insertions, 8 deletions
diff --git a/src/render/graphics.cpp b/src/render/graphics.cpp
index a9dc968db..4c5d1d282 100644
--- a/src/render/graphics.cpp
+++ b/src/render/graphics.cpp
@@ -504,6 +504,7 @@ bool Graphics::resizeScreen(const int width, const int height)
     // +++ need impliment resize in soft mode
 #endif  // USE_OPENGL
 
+    screenResized();
     beginDraw();
     return true;
 
@@ -527,6 +528,7 @@ bool Graphics::resizeScreen(const int width, const int height)
         }
     }
 
+    screenResized();
     beginDraw();
 
     return success;
diff --git a/src/render/graphics.h b/src/render/graphics.h
index e05f23a84..3a051ed55 100644
--- a/src/render/graphics.h
+++ b/src/render/graphics.h
@@ -167,6 +167,9 @@ class Graphics notfinal
          */
         virtual bool resizeScreen(const int width, const int height);
 
+        virtual void restoreContext()
+        { }
+
         /**
          * Draws a resclaled version of the image
          */
@@ -468,6 +471,9 @@ class Graphics notfinal
                                  uint32_t *const arr A_UNUSED)
         { }
 
+        virtual void screenResized()
+        { }
+
         int mWidth;
         int mHeight;
         int mActualWidth;
diff --git a/src/render/modernopenglgraphics.cpp b/src/render/modernopenglgraphics.cpp
index 1fadba3c4..eb245e0de 100644
--- a/src/render/modernopenglgraphics.cpp
+++ b/src/render/modernopenglgraphics.cpp
@@ -117,6 +117,11 @@ ModernOpenGLGraphics::ModernOpenGLGraphics() :
 ModernOpenGLGraphics::~ModernOpenGLGraphics()
 {
     deleteArraysInternal();
+    deleteGLObjects();
+}
+
+void ModernOpenGLGraphics::deleteGLObjects()
+{
     if (mProgram)
         mProgram->decRef();
     if (mVbo)
@@ -191,14 +196,18 @@ void ModernOpenGLGraphics::postInit()
 //    mglVertexAttribIPointer(mPosAttrib, 4, GL_INT, 4 * sizeof(GLint), 0);
     mAttributesCached = mVbo;
 
-    screenResized();
+    mglUniform2f(mScreenUniform,
+        static_cast<float>(mWidth) / 2.0f,
+        static_cast<float>(mHeight) / 2.0f);
 }
 
 void ModernOpenGLGraphics::screenResized()
 {
-    mglUniform2f(mScreenUniform,
-        static_cast<float>(mWidth) / 2.0f,
-        static_cast<float>(mHeight) / 2.0f);
+    deleteGLObjects();
+    mVboCached = 0U;
+    mEboCached = 0U;
+    mAttributesCached = 0U;
+    postInit();
 }
 
 void ModernOpenGLGraphics::deleteArrays()
@@ -1261,7 +1270,10 @@ void ModernOpenGLGraphics::clearScreen() const
 
 void ModernOpenGLGraphics::createGLContext()
 {
-    mGLContext = SDL::createGLContext(mWindow, 3, 3);
+    if (mGLContext)
+        SDL::makeCurrentContext(mGLContext);
+    else
+        mGLContext = SDL::createGLContext(mWindow, 3, 3);
 }
 
 void ModernOpenGLGraphics::finalize(ImageCollection *const col)
diff --git a/src/render/modernopenglgraphics.h b/src/render/modernopenglgraphics.h
index 2b27c621e..86e9f7bf1 100644
--- a/src/render/modernopenglgraphics.h
+++ b/src/render/modernopenglgraphics.h
@@ -64,7 +64,7 @@ class ModernOpenGLGraphics final : public Graphics
         void setColorAll(const Color &color,
                          const Color &color2) override final;
 
-        void screenResized();
+        void screenResized() override final;
 
         void finalize(ImageCollection *const col) override final;
 
@@ -85,6 +85,8 @@ class ModernOpenGLGraphics final : public Graphics
         virtual void createGLContext() override final;
 
     private:
+        void deleteGLObjects();
+
         inline void drawQuad(const Image *const image,
                              const int srcX, const int srcY,
                              const int dstX, const int dstY,
diff --git a/src/utils/glxhelper.cpp b/src/utils/glxhelper.cpp
index 1fedeb9c6..1624b6309 100644
--- a/src/utils/glxhelper.cpp
+++ b/src/utils/glxhelper.cpp
@@ -36,7 +36,7 @@ static int ErrorHandler(Display *d A_UNUSED, XErrorEvent *e A_UNUSED)
     return 0;
 }
 
-void *GlxHelper::createContext(unsigned int window,
+void *GlxHelper::createContext(const unsigned int window,
                                void *const display0,
                                const int major,
                                const int minor)
@@ -117,4 +117,11 @@ void *GlxHelper::createContext(unsigned int window,
     return context2;
 }
 
+bool GlxHelper::makeCurrent(const unsigned int window,
+                            void *const display,
+                            void *const context)
+{
+    return mglXMakeCurrent(static_cast<Display*>(display), window, context);
+}
+
 #endif  // defined(USE_OPENGL) && defined(USE_X11)
diff --git a/src/utils/glxhelper.h b/src/utils/glxhelper.h
index 0378256d0..ce3a5568d 100644
--- a/src/utils/glxhelper.h
+++ b/src/utils/glxhelper.h
@@ -31,10 +31,14 @@
 
 namespace GlxHelper
 {
-    void *createContext(unsigned int window,
+    void *createContext(const unsigned int window,
                         void *const display,
                         const int major,
                         const int minor);
+
+    bool makeCurrent(const unsigned int window,
+                     void *const display,
+                     void *const context);
 }  // namespace Glx
 
 #endif  // defined(USE_OPENGL) && defined(USE_X11)
diff --git a/src/utils/sdl2helper.cpp b/src/utils/sdl2helper.cpp
index 3b2b988a0..07f8d965c 100644
--- a/src/utils/sdl2helper.cpp
+++ b/src/utils/sdl2helper.cpp
@@ -126,4 +126,8 @@ void *SDL::createGLContext(SDL_Window *const window,
     return context;
 }
 
+void SDL::makeCurrentContext(void *const context A_UNUSED)
+{
+}
+
 #endif  // USE_SDL2
diff --git a/src/utils/sdl2helper.h b/src/utils/sdl2helper.h
index 6f59b27a6..b7ab35d84 100644
--- a/src/utils/sdl2helper.h
+++ b/src/utils/sdl2helper.h
@@ -55,6 +55,8 @@ namespace SDL
     void *createGLContext(SDL_Window *const window,
                           const int major,
                           const int minor);
+
+    void makeCurrentContext(void *const context);
 }  // namespace SDL
 
 #endif  // USE_SDL2
diff --git a/src/utils/sdlhelper.cpp b/src/utils/sdlhelper.cpp
index 19cffa0a6..b809fd76b 100644
--- a/src/utils/sdlhelper.cpp
+++ b/src/utils/sdlhelper.cpp
@@ -140,6 +140,16 @@ void *SDL::createGLContext(SDL_Surface *const window A_UNUSED,
     }
     return context;
 }
+
+void SDL::makeCurrentContext(void *const context)
+{
+    SDL_SysWMinfo info;
+    SDL_VERSION(&info.version);
+    SDL_GetWMInfo(&info);
+    GlxHelper::makeCurrent(info.info.x11.window,
+        info.info.x11.display,
+        context);
+}
 #else
 void *SDL::createGLContext(SDL_Surface *const window A_UNUSED,
                            const int major A_UNUSED,
@@ -147,6 +157,10 @@ void *SDL::createGLContext(SDL_Surface *const window A_UNUSED,
 {
     return nullptr;
 }
+
+void SDL::makeCurrentContext(void *const context A_UNUSED)
+{
+}
 #endif
 
 #endif  // USE_SDL2
diff --git a/src/utils/sdlhelper.h b/src/utils/sdlhelper.h
index 328c093cd..92fcaba65 100644
--- a/src/utils/sdlhelper.h
+++ b/src/utils/sdlhelper.h
@@ -60,6 +60,8 @@ namespace SDL
     void *createGLContext(SDL_Surface *const window A_UNUSED,
                           const int major,
                           const int minor);
+
+    void makeCurrentContext(void *const context);
 }  // namespace SDL
 
 #endif  // USE_SDL2