Perliminary support for glGenerateMinMapEXT.

src/osgUtil/CullVisitor.cpp

@@ -1066,6 +1066,7 @@ void CullVisitor::apply(osg::CameraNode& camera)
         if (!rtts)
         {
             rtts = new osgUtil::RenderToTextureStage;
+            rtts->setCameraNode(&camera);
             camera.setRenderingCache(rtts.get());
         }
         else

src/osgUtil/RenderToTextureStage.cpp

@@ -43,6 +43,28 @@ void RenderToTextureStage::reset()
     RenderStage::reset();
 }
 
+class GenerateMipMapHelper : public StateAttribute::ModeUsage
+{
+    public:
+        GenerateMipMapHelper(osg::FBOExtensions* fbo_ext):
+            _fbo_ext(fbo_ext) {}
+            
+        virtual ~GenerateMipMapHelper() {}
+        
+        virtual void usesMode(StateAttribute::GLMode)
+        {
+        }
+
+        virtual void usesTextureMode(StateAttribute::GLMode mode)
+        {
+            _fbo_ext->glGenerateMipmapEXT((GLenum)mode);
+        }
+        
+        osg::FBOExtensions* _fbo_ext;
+        
+};
+
+
 void RenderToTextureStage::draw(osg::State& state,RenderLeaf*& previous)
 {
     
@@ -126,6 +148,23 @@ void RenderToTextureStage::draw(osg::State& state,RenderLeaf*& previous)
         _image->readPixels(_viewport->x(),_viewport->y(),_viewport->width(),_viewport->height(),_imageReadPixelFormat,_imageReadPixelDataType);
     }
        
+    if (fbo_supported && _camera)
+    {
+        // now generate mipmaps if they are required.
+        const osg::CameraNode::BufferAttachmentMap& bufferAttachements = _camera->getBufferAttachmentMap();
+        for(osg::CameraNode::BufferAttachmentMap::const_iterator itr = bufferAttachements.begin();
+            itr != bufferAttachements.end();
+            ++itr)
+        {
+            if (itr->second._texture.valid() && itr->second._mipMapGeneration) 
+            {
+                itr->second._texture->apply(*useState);
+                GenerateMipMapHelper generateMipMap(fbo_ext);
+                itr->second._texture->getModeUsage(generateMipMap);
+            }
+        }
+    }
+    
     if (_camera && _camera->getPostDrawCallback())
     {
         // if we have a camera with a post draw callback invoke it.