add framebuffer support for old video cards

src/framework/graphics/framebuffer.cpp

@@ -79,6 +79,9 @@ FrameBuffer::FrameBuffer(int width, int height)
         // otherwise fallback to copy texture from screen implementation
         m_fallbackOldImp = true;
     }
+
+    if(m_fallbackOldImp)
+        logInfo("Framebuffers not supported, falling back to old implementation.");
 }
 
 FrameBuffer::~FrameBuffer()
@@ -92,13 +95,23 @@ void FrameBuffer::bind()
     if(!m_fallbackOldImp) {
         // bind framebuffer
         oglBindFramebuffer(GL_FRAMEBUFFER_EXT, m_fbo);
+    } else {
+        int screenWidth = g_graphics.getScreenSize().width();
+        int screenHeight = g_graphics.getScreenSize().height();
+
+        if(!m_screenBackup || m_screenBackup->getSize() != g_graphics.getScreenSize())
+            m_screenBackup = TexturePtr(new Texture(screenWidth, screenHeight, 4));
+
+        // save screen state
+        glBindTexture(GL_TEXTURE_2D, m_screenBackup->getId());
+        glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 0, 0, screenWidth, screenHeight);
     }
 
     // setup framebuffer viewport
     glViewport(0, 0, m_texture->getWidth(), m_texture->getHeight());
     glMatrixMode(GL_PROJECTION);
     glLoadIdentity();
-    glOrtho(0.0f, m_texture->getWidth(), 0, m_texture->getHeight(), -1, 1);
+    glOrtho(0.0f, m_texture->getWidth(), m_texture->getHeight(), 0, -1, 1);
 
     // back to model view
     glMatrixMode(GL_MODELVIEW);
@@ -127,13 +140,14 @@ void FrameBuffer::unbind()
         // restore graphics viewport
         g_graphics.restoreViewport();
 
-        // clear screen
+        // restore screen
         glClearColor(0.0, 0.0, 0.0, 1.0);
         glClear(GL_COLOR_BUFFER_BIT);
+        g_graphics.drawTexturedRect(Rect(Point(0,0), g_graphics.getScreenSize()), m_screenBackup, Rect(), true);
     }
 }
 
 void FrameBuffer::draw(const Rect& screenCoords, const Rect& framebufferCoords)
 {
-    g_graphics.drawTexturedRect(screenCoords, m_texture, framebufferCoords);
+    g_graphics.drawTexturedRect(screenCoords, m_texture, framebufferCoords, true);
 }

src/framework/graphics/framebuffer.h

@@ -44,6 +44,7 @@ public:
 
 private:
     TexturePtr m_texture;
+    TexturePtr m_screenBackup;
     uint m_fbo;
     bool m_fallbackOldImp;
 };

src/framework/graphics/graphics.cpp

@@ -132,7 +132,8 @@ void Graphics::endRender()
 
 void Graphics::drawTexturedRect(const Rect& screenCoords,
                                 const TexturePtr& texture,
-                                const Rect& textureCoords)
+                                const Rect& textureCoords,
+                                bool upsideDown)
 {
     if(screenCoords.isEmpty() || texture->getId() == 0)
         return;
@@ -151,13 +152,23 @@ void Graphics::drawTexturedRect(const Rect& screenCoords,
 
     if(textureCoords.isEmpty()) {
         textureRight = texture->getWidth() / (float)textureSize.width();
+        if(upsideDown) {
+            textureBottom = 0.0f;
+            textureTop = texture->getHeight()  / (float)textureSize.height();
+        } else {
             textureBottom = texture->getHeight()  / (float)textureSize.height();
             textureTop = 0.0f;
+        }
         textureLeft = 0.0f;
     } else {
         textureRight = (textureCoords.right() + 1) / (float)textureSize.width();
+        if(upsideDown) {
+            textureTop = (textureCoords.bottom() + 1) / (float)textureSize.height();
+            textureBottom = textureCoords.top() / (float)textureSize.height();
+        } else {
             textureBottom = (textureCoords.bottom() + 1) / (float)textureSize.height();
             textureTop = textureCoords.top() / (float)textureSize.height();
+        }
         textureLeft = textureCoords.left() / (float)textureSize.width();
     }
 

src/framework/graphics/graphics.h

@@ -56,7 +56,8 @@ public:
     // drawing API
     void drawTexturedRect(const Rect& screenCoords,
                           const TexturePtr& texture,
-                          const Rect& textureCoords = Rect());
+                          const Rect& textureCoords = Rect(),
+                          bool upsideDown = false);
 
     void drawRepeatedTexturedRect(const Rect& screenCoords,
                                   const TexturePtr& texture,