/*

-----------------------------------------------------------------------------

This source file is part of OGRE

    (Object-oriented Graphics Rendering Engine)

For the latest info, see http://www.ogre3d.org/

Copyright (c) 2000-2014 Torus Knot Software Ltd

Permission is hereby granted, free of charge, to any person obtaining a copy

of this software and associated documentation files (the "Software"), to deal

in the Software without restriction, including without limitation the rights

to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

copies of the Software, and to permit persons to whom the Software is

furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in

all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

THE SOFTWARE.

-----------------------------------------------------------------------------

*/

#ifndef __Lod_Strategy_H__

#define __Lod_Strategy_H__

#include "OgrePrerequisites.h"

#include "OgreMesh.h"

#include "OgreMaterial.h"

#include "OgreHeaderPrefix.h"

namespace Ogre {

    /** \addtogroup Core

    *  @{

    */

    /** \defgroup LOD Level of Detail

    *  @{

    */

    /** Strategy for determining level of detail.

        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

    {

    private:

        /** 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.

            By default, performs no transformation.

            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