source: GTP/branches/IllumWPdeliver2008dec/IlluminationWP/precompiled/include/IllumModule/RenderTechniques/HierarchicalParticleSystemTechnique.h @ 3255

#pragma once
#include "RenderTechnique.h"

/**
        @brief Base abstract class __declspec( dllexport ) of rendering a hierarchical particle system.

        A hierarchical particle system is a particle system made out of a smaller particle system. 
        It renders an image of the smaller particle system and multiplies this image to achieve a bigger particle system.
        This way fewer computation is needed to simulate large number of particles, while the trick is usually unnoticable.
*/
class __declspec( dllexport ) HierarchicalParticleSystemTechnique : virtual public RenderTechnique
{
public:
        /**
                @brief Constructor.

                @param startFrame                               adds an offset to the current frame number to help evenly distribute updates between frames
                @param impostorUpdateInterval   update frequency of the impostor texture (image of the smaller system)
                @param impostorResolution               resolution of the impostor texture
                @param useDistCalc                              flag to skip impostor update if object is far away (//not used)
                @param perspectiveRendering             sets if the impostor should be rendered with a perspective projection or orthogonal
                @param parentRenderable                 the object to operate on
                @param parentTechniqueGroup             the TechniqueGroup this RenderedTechnique is attached to
        */
        HierarchicalParticleSystemTechnique(
                                                        unsigned long startFrame,
                                                        unsigned long impostorUpdateInterval,
                                                        unsigned int impostorResolution,
                                                        bool useDistCalc,
                                                        bool perspectiveRendering,
                                                        ElementaryRenderable* parentRenderable,
                                                        TechniqueGroup* parentTechniqueGroup
                                                        );
        virtual ~HierarchicalParticleSystemTechnique();

        //inherited
        void update(unsigned long frameNum);
        //inherited
        void runChanged(RenderingRunType runType, RenderingRun* run);
        //inherited
        void runUpdated(RenderingRunType runType, RenderingRun* run);

protected:
        /**
                        @brief update frequency of the impostor texture (image of the smaller system)
        */
        unsigned long impostorUpdateInterval;
        /**
                        @brief resolution of the impostor texture
        */
        unsigned int impostorResolution;
        /**
                        @brief offset in frame number used during update
        */
        unsigned long startFrame;       
        /**
                        @brief flag to skip impostor update if object is far away (//not used)
        */
        bool useDistCalc;
        /**
                        @brief sets if the impostor should be rendered with a perspective projection or orthogonal
        */
        bool perspectiveRendering;
        /**
                        @brief Creates the ChildParticleSystemRenderingRun needed by this technique.

                        @return pointer to the ChildParticleSystemRenderingRun created instance
        */
        virtual RenderingRun* createChildPSysRenderingRun()=0;  
        /**
                        @brief Called if the impostor rendering run changed.

                        @param run pointer to the new ChildParticleSystemRenderingRun instance to use
        */
        virtual void impostorChanged(RenderingRun* run) = 0;
        /**
                        @brief Called if the impostor rendering run is updated.

                        @param run pointer to the updated ChildParticleSystemRenderingRu.
        */
        virtual void impostorUpdated(RenderingRun* run) = 0;
        
};