source: downloads/ogre_src_v1-9-0/OgreMain/include/OgreLodStrategy.h @ 153

/*
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This source file is part of OGRE
    (Object-oriented Graphics Rendering Engine)
For the latest info, see http://www.ogre3d.org/

Copyright (c) 2000-2013 Torus Knot Software Ltd

Permission is hereby granted, free of charge, to any person obtaining a copy
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all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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THE SOFTWARE.
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*/
#ifndef __Lod_Strategy_H__
#define __Lod_Strategy_H__

#include "OgrePrerequisites.h"

#include "OgreMesh.h"

#include "OgreMovableObject.h"
#include "OgreCamera.h"
#include "OgreHeaderPrefix.h"

namespace Ogre {

        /** \addtogroup Core
        *  @{
        */
        /** \addtogroup LOD
        *  @{
        */
        /** Strategy for determining level of detail.
    @remarks
        Generally, to create a new LOD strategy, all of the following will
        need to be implemented: getValueImpl, getBaseValue, transformBias,
        getIndex, sort, and isSorted.
        In addition, transformUserValue may be overridden.
    */
        class _OgreExport LodStrategy : public LodAlloc
    {
    protected:
        /** Name of this strategy. */
        String mName;

        /** Compute the LOD value for a given movable object relative to a given camera. */
        virtual Real getValueImpl(const MovableObject *movableObject, const Camera *camera) const = 0;

    public:
        /** Constructor accepting name. */
        LodStrategy(const String& name);

        /** Virtual destructor. */
        virtual ~LodStrategy();

        /** Get the value of the first (highest) level of detail. */
        virtual Real getBaseValue() const = 0;

        /** Transform LOD bias so it only needs to be multiplied by the LOD value. */
        virtual Real transformBias(Real factor) const = 0;

        /** Transform user supplied value to internal value.
        @remarks
            By default, performs no transformation.
        @remarks
            Do not throw exceptions for invalid values here, as the LOD strategy
            may be changed such that the values become valid.
        */
        virtual Real transformUserValue(Real userValue) const;

        /** Compute the LOD value for a given movable object relative to a given camera. */
        Real getValue(const MovableObject *movableObject, const Camera *camera) const;

        /** Get the index of the LOD usage which applies to a given value. */
        virtual ushort getIndex(Real value, const Mesh::MeshLodUsageList& meshLodUsageList) const = 0;

        /** Get the index of the LOD usage which applies to a given value. */
        virtual ushort getIndex(Real value, const Material::LodValueList& materialLodValueList) const = 0;

        /** Sort mesh LOD usage list from greatest to least detail */
        virtual void sort(Mesh::MeshLodUsageList& meshLodUsageList) const = 0;

        /** Determine if the LOD values are sorted from greatest detail to least detail. */
        virtual bool isSorted(const Mesh::LodValueList& values) const = 0;

        /** Assert that the LOD values are sorted from greatest detail to least detail. */
        void assertSorted(const Mesh::LodValueList& values) const;

        /** Get the name of this strategy. */
        const String& getName() const { return mName; }

    protected:
        /** Implementation of isSorted suitable for ascending values. */
        static bool isSortedAscending(const Mesh::LodValueList& values);
        /** Implementation of isSorted suitable for descending values. */
        static bool isSortedDescending(const Mesh::LodValueList& values);

        /** Implementation of sort suitable for ascending values. */
        static void sortAscending(Mesh::MeshLodUsageList& meshLodUsageList);
        /** Implementation of sort suitable for descending values. */
        static void sortDescending(Mesh::MeshLodUsageList& meshLodUsageList);

        /** Implementation of getIndex suitable for ascending values. */
        static ushort getIndexAscending(Real value, const Mesh::MeshLodUsageList& meshLodUsageList);
        /** Implementation of getIndex suitable for descending values. */
        static ushort getIndexDescending(Real value, const Mesh::MeshLodUsageList& meshLodUsageList);

        /** Implementation of getIndex suitable for ascending values. */
        static ushort getIndexAscending(Real value, const Material::LodValueList& materialLodValueList);
        /** Implementation of getIndex suitable for descending values. */
        static ushort getIndexDescending(Real value, const Material::LodValueList& materialLodValueList);

    };
        /** @} */
        /** @} */

} // namespace

#include "OgreHeaderSuffix.h"

#endif