graphics optimization feature inspirated by diablo3 engine

* the rendering now consits of two panes
- the background pane (for animated stuff like the map)
- the foreground pane (for steady stuff, like UI)
each pane has it own max FPS and works idependently
this may increase graphics performance on many platforms

src/framework/graphics/framebuffer.cpp

@@ -75,7 +75,7 @@ void FrameBuffer::resize(const Size& size)
             logFatal("Unable to setup framebuffer object");
         internalRelease();
     } else {
-        m_screenBackup = TexturePtr(new Texture(size.width(), size.height(), 4));
+        m_screenBackup = TexturePtr(new Texture(size.width(), size.height()));
     }
 }
 
@@ -113,6 +113,12 @@ void FrameBuffer::release()
     g_graphics.setViewportSize(m_oldViewportSize);
 }
 
+void FrameBuffer::draw()
+{
+    Rect rect(0,0, getSize());
+    g_painter->drawTexturedRect(rect, m_texture, rect);
+}
+
 void FrameBuffer::draw(const Rect& dest, const Rect& src)
 {
     g_painter->drawTexturedRect(dest, m_texture, src);
@@ -132,9 +138,7 @@ void FrameBuffer::internalBind()
         boundFbo = m_fbo;
     } else {
         // backup screen color buffer into a texture
-        m_screenBackup->bind();
-        Size size = getSize();
-        glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 0, 0, size.width(), size.height());
+        m_screenBackup->copyFromScreen(Rect(0, 0, getSize()));
     }
 }
 
@@ -145,16 +149,14 @@ void FrameBuffer::internalRelease()
         glBindFramebuffer(GL_FRAMEBUFFER, m_prevBoundFbo);
         boundFbo = m_prevBoundFbo;
     } else {
-        Size size = getSize();
+        Rect screenRect(0, 0, getSize());
 
         // copy the drawn color buffer into the framebuffer texture
-        m_texture->bind();
-        glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 0, 0, size.width(), size.height());
+        m_texture->copyFromScreen(screenRect);
 
         // restore screen original content
-        glDisable(GL_BLEND);
-        g_painter->drawTexturedRect(Rect(0, 0, size), m_screenBackup, Rect(0, 0, size));
-        glEnable(GL_BLEND);
+        g_painter->setCompositionMode(Painter::CompositionMode_Replace);
+        g_painter->drawTexturedRect(screenRect, m_screenBackup, screenRect);
     }
 }
 

src/framework/graphics/framebuffer.h

@@ -37,6 +37,7 @@ public:
     void bind();
     void clear(const Color& color = Color::black, const Rect& rect = Rect());
     void release();
+    void draw();
     void draw(const Rect& dest);
     void draw(const Rect& dest, const Rect& src);
 

src/framework/graphics/graphics.cpp

@@ -88,7 +88,6 @@ void Graphics::init()
 
     selectPainterEngine(m_prefferedPainterEngine);
     m_emptyTexture = TexturePtr(new Texture);
-
 }
 
 void Graphics::terminate()

src/framework/graphics/painter.cpp

@@ -53,7 +53,7 @@ void Painter::refreshState()
     updateGlTexture();
 }
 
-void Painter::saveAndResetState()
+void Painter::saveState()
 {
     assert(m_oldStateIndex<10);
     m_olderStates[m_oldStateIndex].projectionMatrix = m_projectionMatrix;
@@ -65,6 +65,11 @@ void Painter::saveAndResetState()
     m_olderStates[m_oldStateIndex].shaderProgram = m_shaderProgram;
     m_olderStates[m_oldStateIndex].texture = m_texture;
     m_oldStateIndex++;
+}
+
+void Painter::saveAndResetState()
+{
+    saveState();
     resetState();
 }
 

src/framework/graphics/painter.h

@@ -62,6 +62,7 @@ public:
 
     void resetState();
     virtual void refreshState();
+    void saveState();
     void saveAndResetState();
     void restoreSavedState();
 

src/framework/graphics/particle.cpp

@@ -50,9 +50,10 @@ void Particle::render()
     if(!m_texture)
         g_painter->drawFilledRect(m_rect);
     else {
+        g_painter->saveState();
         g_painter->setCompositionMode(m_compositionMode);
         g_painter->drawTexturedRect(m_rect, m_texture);
-        g_painter->setCompositionMode(Painter::CompositionMode_Normal);
+        g_painter->restoreSavedState();
     }
 }
 

src/framework/graphics/texture.cpp

@@ -129,6 +129,12 @@ uint Texture::internalLoadGLTexture(uchar *pixels, int channels, int width, int
     return id;
 }
 
+void Texture::copyFromScreen(const Rect& screenRect)
+{
+    bind();
+    glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, screenRect.x(), screenRect.y(), screenRect.width(), screenRect.height());
+}
+
 void Texture::bind()
 {
     // must reset painter texture state

src/framework/graphics/texture.h

@@ -30,9 +30,11 @@ class Texture : public std::enable_shared_from_this<Texture>
 public:
     Texture();
     Texture(const ImagePtr& image);
-    Texture(int width, int height, int channels, uchar* pixels = NULL);
+    Texture(int width, int height, int channels = 4, uchar* pixels = NULL);
     virtual ~Texture();
 
+    void copyFromScreen(const Rect& screenRect);
+
     void bind();
 
     /// Tries to generate mipmaps via hardware, otherwise fallback to software implementation