Ogre Composition解析

enum PassType
        {
            PT_CLEAR,           /// Clear target to one colour
            PT_STENCIL,         /// Set stencil operation
            PT_RENDERSCENE,     /// Render the scene or part of it
            PT_RENDERQUAD,      /// Render a full screen quad
            PT_RENDERCUSTOM     /// Render a custom sequence
        };

enum InputMode
        {
            IM_NONE,        /// No input
            IM_PREVIOUS     /// Output of previous Composition in chain
        };

class TextureDefinition : public CompositorInstAlloc
        {
        public:
            String name;
            //Texture definition being a reference is determined by these two fields not being empty.
            String refCompName; //If a reference, the name of the compositor being referenced
            String refTexName;  //If a reference, the name of the texture in the compositor being referenced
            size_t width;       // 0 means adapt to target width
            size_t height;      // 0 means adapt to target height
            float widthFactor;  // multiple of target width to use (if width = 0)
            float heightFactor; // multiple of target height to use (if height = 0)
            PixelFormatList formatList; // more than one means MRT
            bool fsaa;          // FSAA enabled; true = determine from main target (if render_scene), false = disable
            bool hwGammaWrite;  // Do sRGB gamma correction on write (only 8-bit per channel formats) 
            uint16 depthBufferId;//Depth Buffer‘s pool ID. (unrelated to "pool" variable below)
            bool pooled;        // whether to use pooled textures for this one
            TextureScope scope; // Which scope has access to this texture

            TextureDefinition() :width(0), height(0), widthFactor(1.0f), heightFactor(1.0f), 
                fsaa(true), hwGammaWrite(false), depthBufferId(1), pooled(false), scope(TS_LOCAL) {}
        };

class TargetOperation
        {
        public:
            TargetOperation()
            { 
            }
            TargetOperation(RenderTarget *inTarget):
                target(inTarget), currentQueueGroupID(0), visibilityMask(0xFFFFFFFF),
                lodBias(1.0f),
                onlyInitial(false), hasBeenRendered(false), findVisibleObjects(false), 
                materialScheme(MaterialManager::DEFAULT_SCHEME_NAME), shadowsEnabled(true)
            { 
            }
            /// Target
            RenderTarget *target;

            /// Current group ID
            int currentQueueGroupID;

            /// RenderSystem operations to queue into the scene manager, by
            /// uint8
            RenderSystemOpPairs renderSystemOperations;

            /// Scene visibility mask
            /// If this is 0, the scene is not rendered at all
            uint32 visibilityMask;
            
            /// LOD offset. This is multiplied with the camera LOD offset
            /// 1.0 is default, lower means lower detail, higher means higher detail
            float lodBias;
            
            /** A set of render queues to either include or exclude certain render queues.
            */
            typedef std::bitset<RENDER_QUEUE_COUNT> RenderQueueBitSet;

            /// Which renderqueues to render from scene
            RenderQueueBitSet renderQueues;
            
            /** @see CompositionTargetPass::mOnlyInitial
            */
            bool onlyInitial;
            /** "Has been rendered" flag; used in combination with
                onlyInitial to determine whether to skip this target operation.
            */
            bool hasBeenRendered;
            /** Whether this op needs to find visible scene objects or not 
            */
            bool findVisibleObjects;
            /** Which material scheme this op will use */
            String materialScheme;
            /** Whether shadows will be enabled */
            bool shadowsEnabled;
        };

class _OgreExport RenderSystemOperation : public CompositorInstAlloc
        {
        public:
            virtual ~RenderSystemOperation();
            /// Set state to SceneManager and RenderSystem
            virtual void execute(SceneManager *sm, RenderSystem *rs) = 0;
        };

class _OgreExport RQListener: public RenderQueueListener
        {
        public:
            RQListener() : mOperation(0), mSceneManager(0), mRenderSystem(0), mViewport(0) {}

            /** @copydoc RenderQueueListener::renderQueueStarted
            */
            virtual void renderQueueStarted(uint8 queueGroupId, const String& invocation, bool& skipThisInvocation);
            /** @copydoc RenderQueueListener::renderQueueEnded
            */
            virtual void renderQueueEnded(uint8 queueGroupId, const String& invocation, bool& repeatThisInvocation);

            /** Set current operation and target. */
            void setOperation(CompositorInstance::TargetOperation *op,SceneManager *sm,RenderSystem *rs);

            /** Notify current destination viewport. */
            void notifyViewport(Viewport* vp) { mViewport = vp; }

            /** Flush remaining render system operations. */
            void flushUpTo(uint8 id);
        private:
            CompositorInstance::TargetOperation *mOperation;
            SceneManager *mSceneManager;
            RenderSystem *mRenderSystem;
            Viewport* mViewport;
            CompositorInstance::RenderSystemOpPairs::iterator currentOp, lastOp;
        };

    class _OgreExport CompositorTranslator : public ScriptTranslator
    {
    protected:
        Compositor *mCompositor;
    public:
        CompositorTranslator();
        void translate(ScriptCompiler *compiler, const AbstractNodePtr &node);
    };
    class _OgreExport CompositionTechniqueTranslator : public ScriptTranslator
    {
    protected:
        CompositionTechnique *mTechnique;
    public:
        CompositionTechniqueTranslator();
        void translate(ScriptCompiler *compiler, const AbstractNodePtr &node);
    };
    class _OgreExport CompositionTargetPassTranslator : public ScriptTranslator
    {
    protected:
        CompositionTargetPass *mTarget;
    public:
        CompositionTargetPassTranslator();
        void translate(ScriptCompiler *compiler, const AbstractNodePtr &node);
    };
    class _OgreExport CompositionPassTranslator : public ScriptTranslator
    {
    protected:
        CompositionPass *mPass;
    public:
        CompositionPassTranslator();
        void translate(ScriptCompiler *compiler, const AbstractNodePtr &node);
    };

CompositorChain::CompositorChain(Viewport *vp):
    mViewport(vp),
    mOriginalScene(0),
    mDirty(true),
    mAnyCompositorsEnabled(false)
{
    assert(vp);
    mOldClearEveryFrameBuffers = vp->getClearBuffers();
    vp->addListener(this);

    createOriginalScene();
    vp->getTarget()->addListener(this);
}

class _OgreGLExport GLFBORenderTexture: public GLRenderTexture
    {
    public:
        GLFBORenderTexture(GLFBOManager *manager, const String &name, const GLSurfaceDesc &target, bool writeGamma, uint fsaa);

        virtual void getCustomAttribute(const String& name, void* pData);

        /// Override needed to deal with multisample buffers
        virtual void swapBuffers();

        /// Override so we can attach the depth buffer to the FBO
        virtual bool attachDepthBuffer( DepthBuffer *depthBuffer );
        virtual void detachDepthBuffer();
        virtual void _detachDepthBuffer();
    protected:
        GLFrameBufferObject mFB;
    };

void CompositorInstance::_compileTargetOperations(CompiledState &compiledState)
{
    /// Collect targets of previous state
    if(mPreviousInstance)
        mPreviousInstance->_compileTargetOperations(compiledState);
    /// Texture targets
    CompositionTechnique::TargetPassIterator it = mTechnique->getTargetPassIterator();
    while(it.hasMoreElements())
    {
        CompositionTargetPass *target = it.getNext();
        
        TargetOperation ts(getTargetForTex(target->getOutputName()));
        /// Set "only initial" flag, visibilityMask and lodBias according to CompositionTargetPass.
        ts.onlyInitial = target->getOnlyInitial();
        ts.visibilityMask = target->getVisibilityMask();
        ts.lodBias = target->getLodBias();
        ts.shadowsEnabled = target->getShadowsEnabled();
        ts.materialScheme = target->getMaterialScheme();
        /// Check for input mode previous
        if(target->getInputMode() == CompositionTargetPass::IM_PREVIOUS)
        {
            /// Collect target state for previous compositor
            /// The TargetOperation for the final target is collected separately as it is merged
            /// with later operations
            mPreviousInstance->_compileOutputOperation(ts);
        }
        /// Collect passes of our own target
        collectPasses(ts, target);
        compiledState.push_back(ts);
    }
}

void CompositorChain::preTargetOperation(CompositorInstance::TargetOperation &op, Viewport *vp, Camera *cam)
{
    if (cam)
    {
        SceneManager *sm = cam->getSceneManager();
        /// Set up render target listener
        mOurListener.setOperation(&op, sm, sm->getDestinationRenderSystem());
        mOurListener.notifyViewport(vp);
        /// Register it
        sm->addRenderQueueListener(&mOurListener);
        /// Set whether we find visibles
        mOldFindVisibleObjects = sm->getFindVisibleObjects();
        sm->setFindVisibleObjects(op.findVisibleObjects);
        /// Set LOD bias level
        mOldLodBias = cam->getLodBias();
        cam->setLodBias(cam->getLodBias() * op.lodBias);
    }

    // Set the visibility mask
    mOldVisibilityMask = vp->getVisibilityMask();
    vp->setVisibilityMask(op.visibilityMask);
    /// Set material scheme 
    mOldMaterialScheme = vp->getMaterialScheme();
    vp->setMaterialScheme(op.materialScheme);
    /// Set shadows enabled
    mOldShadowsEnabled = vp->getShadowsEnabled();
    vp->setShadowsEnabled(op.shadowsEnabled);
    /// XXX TODO
    //vp->setClearEveryFrame( true );
    //vp->setOverlaysEnabled( false );
    //vp->setBackgroundColour( op.clearColour );
}

void CompositorChain::RQListener::flushUpTo(uint8 id)
{
    /// Process all RenderSystemOperations up to and including render queue id.
    /// Including, because the operations for RenderQueueGroup x should be executed
    /// at the beginning of the RenderQueueGroup render for x.
    while(currentOp != lastOp && currentOp->first <= id)
    {
        currentOp->second->execute(mSceneManager, mRenderSystem);
        ++currentOp;
    }
}

void CompositorChain::RQListener::renderQueueStarted(uint8 id, 
    const String& invocation, bool& skipThisQueue)
{
    // Skip when not matching viewport
    // shadows update is nested within main viewport update
    if (mSceneManager->getCurrentViewport() != mViewport)
        return;

    flushUpTo(id);
    /// If no one wants to render this queue, skip it
    /// Don‘t skip the OVERLAY queue because that‘s handled separately
    if(!mOperation->renderQueues.test(id) && id!=RENDER_QUEUE_OVERLAY)
    {
        skipThisQueue = true;
    }
}