/*

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

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 __Mesh_H__

#define __Mesh_H__

#include "OgrePrerequisites.h"

#include "OgreResource.h"

#include "OgreAxisAlignedBox.h"

#include "OgreVertexBoneAssignment.h"

#include "OgreAnimation.h"

#include "OgreAnimationTrack.h"

#include "OgreHeaderPrefix.h"

#include "OgreSharedPtr.h"

#include "OgreUserObjectBindings.h"

#include "OgreVertexIndexData.h"

namespace Ogre {

    /** \addtogroup Core

    *  @{

    */

    /** \addtogroup Resources

    *  @{

    */

    struct MeshLodUsage;

    class LodStrategy;

    /** Resource holding data about 3D mesh.

        This class holds the data used to represent a discrete

        3-dimensional object. Mesh data usually contains more

        than just vertices and triangle information; it also

        includes references to materials (and the faces which use them),

        level-of-detail reduction information, convex hull definition,

        skeleton/bones information, keyframe animation etc.

        However, it is important to note the emphasis on the word

        'discrete' here. This class does not cover the large-scale

        sprawling geometry found in level / landscape data.

    @par

        Multiple world objects can (indeed should) be created from a

        single mesh object - see the Entity class for more info.

        The mesh object will have it's own default

        material properties, but potentially each world instance may

        wish to customise the materials from the original. When the object

        is instantiated into a scene node, the mesh material properties

        will be taken by default but may be changed. These properties

        are actually held at the SubMesh level since a single mesh may

        have parts with different materials.

    @par

        As described above, because the mesh may have sections of differing

        material properties, a mesh is inherently a compound construct,

        consisting of one or more SubMesh objects.

        However, it strongly 'owns' it's SubMeshes such that they

        are loaded / unloaded at the same time. This is contrary to

        the approach taken to hierarchically related (but loosely owned)

        scene nodes, where data is loaded / unloaded separately. Note

        also that mesh sub-sections (when used in an instantiated object)

        share the same scene node as the parent.

    */

    class _OgreExport Mesh: public Resource, public AnimationContainer

    {

        friend class SubMesh;

        friend class MeshSerializerImpl;

        friend class MeshSerializerImpl_v1_8;

        friend class MeshSerializerImpl_v1_4;

        friend class MeshSerializerImpl_v1_3;

        friend class MeshSerializerImpl_v1_2;

        friend class MeshSerializerImpl_v1_1;

    public:

        typedef std::vector<Real> LodValueList;

        typedef std::vector<MeshLodUsage> MeshLodUsageList;

        /// Multimap of vertex bone assignments (orders by vertex index).

        typedef std::multimap<size_t, VertexBoneAssignment> VertexBoneAssignmentList;

        typedef MapIterator<VertexBoneAssignmentList> BoneAssignmentIterator;

        typedef std::vector<SubMesh*> SubMeshList;

        typedef std::vector<unsigned short> IndexMap;

    private:

        /** A list of submeshes which make up this mesh.

            Each mesh is made up of 1 or more submeshes, which

            are each based on a single material and can have their

            own vertex data (they may not - they can share vertex data

            from the Mesh, depending on preference).

        */

        SubMeshList mSubMeshList;

        /** Internal method for making the space for a vertex element to hold tangents. */

        void organiseTangentsBuffer(VertexData *vertexData, 

            VertexElementSemantic targetSemantic, unsigned short index, 

            unsigned short sourceTexCoordSet);

    public:

        /** A hashmap used to store optional SubMesh names.

            Translates a name into SubMesh index.

        */

        typedef std::unordered_map<String, ushort> SubMeshNameMap ;

    private:

        DataStreamPtr mFreshFromDisk;

        SubMeshNameMap mSubMeshNameMap ;

        UserObjectBindings mUserObjectBindings;

        /// Local bounding box volume.

        AxisAlignedBox mAABB;

        /// Local bounding sphere radius (centered on object).

        Real mBoundRadius;

        /// Largest bounding radius of any bone in the skeleton (centered on each bone, only considering verts weighted to the bone)

        Real mBoneBoundingRadius;

        /// Optional linked skeleton.

        SkeletonPtr mSkeleton;

        VertexBoneAssignmentList mBoneAssignments;

        /// Flag indicating that bone assignments need to be recompiled.

        bool mBoneAssignmentsOutOfDate;

        /** Build the index map between bone index and blend index. */

        void buildIndexMap(const VertexBoneAssignmentList& boneAssignments,

            IndexMap& boneIndexToBlendIndexMap, IndexMap& blendIndexToBoneIndexMap);

        /** Compile bone assignments into blend index and weight buffers. */

        void compileBoneAssignments(const VertexBoneAssignmentList& boneAssignments,

            unsigned short numBlendWeightsPerVertex, 

            IndexMap& blendIndexToBoneIndexMap,

            VertexData* targetVertexData);

#if !OGRE_NO_MESHLOD

        const LodStrategy *mLodStrategy;

        bool mHasManualLodLevel;

        ushort mNumLods;

        MeshLodUsageList mMeshLodUsageList;

#else

        const LodStrategy *mLodStrategy;

        const bool mHasManualLodLevel;

        const ushort mNumLods;

        MeshLodUsageList mMeshLodUsageList;

#endif

        HardwareBufferManagerBase* mBufferManager;

        HardwareBufferUsage mVertexBufferUsage;

        HardwareBufferUsage mIndexBufferUsage;

        bool mVertexBufferShadowBuffer;

        bool mIndexBufferShadowBuffer;

        bool mPreparedForShadowVolumes;

        bool mEdgeListsBuilt;

        bool mAutoBuildEdgeLists;

        /// Storage of morph animations, lookup by name

        AnimationList mAnimationsList;

        /// The vertex animation type associated with the shared vertex data

        mutable VertexAnimationType mSharedVertexDataAnimationType;

        /// Whether vertex animation includes normals

        mutable bool mSharedVertexDataAnimationIncludesNormals;

        /// Do we need to scan animations for animation types?

        mutable bool mAnimationTypesDirty;

        /// List of available poses for shared and dedicated geometryPoseList

        PoseList mPoseList;

        mutable bool mPosesIncludeNormals;

        /** Loads the mesh from disk.  This call only performs IO, it

            does not parse the bytestream or check for any errors therein.

            It also does not set up submeshes, etc.  You have to call load()

            to do that.

         */

        void prepareImpl(void) override;

        /** Destroys data cached by prepareImpl.

         */

        void unprepareImpl(void) override;

        /// @copydoc Resource::loadImpl

        void loadImpl(void) override;

        /// @copydoc Resource::postLoadImpl

        void postLoadImpl(void) override;

        /// @copydoc Resource::unloadImpl

        void unloadImpl(void) override;

        /// @copydoc Resource::calculateSize

        size_t calculateSize(void) const override;

        void mergeAdjacentTexcoords( unsigned short finalTexCoordSet,

                                     unsigned short texCoordSetToDestroy, VertexData *vertexData );

    public:

        /** Default constructor - used by MeshManager

        @warning

            Do not call this method directly.

        */

        Mesh(ResourceManager* creator, const String& name, ResourceHandle handle,

            const String& group, bool isManual = false, ManualResourceLoader* loader = 0);

        ~Mesh();

        // NB All methods below are non-virtual since they will be

        // called in the rendering loop - speed is of the essence.

        /** Creates a new SubMesh.

            Method for manually creating geometry for the mesh.

            Note - use with extreme caution - you must be sure that

            you have set up the geometry properly.

        */

        SubMesh* createSubMesh(void);

        /** Creates a new SubMesh and gives it a name

        */

        SubMesh* createSubMesh(const String& name);

        /** Gives a name to a SubMesh

        */

        void nameSubMesh(const String& name, ushort index);

        /** Removes a name from a SubMesh

        */

        void unnameSubMesh(const String& name);

        /** Gets the index of a submesh with a given name.

            Useful if you identify the SubMeshes by name (using nameSubMesh)

            but wish to have faster repeat access.

        */

        ushort _getSubMeshIndex(const String& name) const;

        /** Gets the number of sub meshes which comprise this mesh.

        *  @deprecated use getSubMeshes() instead

        */

        size_t getNumSubMeshes(void) const {

            return mSubMeshList.size();

        }

        /** Gets a pointer to the submesh indicated by the index.

        *  @deprecated use getSubMeshes() instead

        */

        SubMesh* getSubMesh(size_t index) const {

            return mSubMeshList[index];

        }

        /** Gets a SubMesh by name

        */

        SubMesh* getSubMesh(const String& name) const ;

        /** Destroy a SubMesh with the given index. 

        @note

            This will invalidate the contents of any existing Entity, or

            any other object that is referring to the SubMesh list. Entity will

            detect this and reinitialise, but it is still a disruptive action.

        */

        void destroySubMesh(unsigned short index);

        /** Destroy a SubMesh with the given name. 

        @note

            This will invalidate the contents of any existing Entity, or

            any other object that is referring to the SubMesh list. Entity will

            detect this and reinitialise, but it is still a disruptive action.

        */

        void destroySubMesh(const String& name);

        typedef VectorIterator<SubMeshList> SubMeshIterator;

        /// Gets an iterator over the available submeshes

        /// @deprecated use getSubMeshes() instead

        OGRE_DEPRECATED SubMeshIterator getSubMeshIterator(void)

        { return SubMeshIterator(mSubMeshList.begin(), mSubMeshList.end()); }

        /// Gets the available submeshes

        const SubMeshList& getSubMeshes() const {

            return mSubMeshList;

        }

        /** Shared vertex data.

            This vertex data can be shared among multiple submeshes. SubMeshes may not have

            their own VertexData, they may share this one.

        @par

            The use of shared or non-shared buffers is determined when

            model data is converted to the OGRE .mesh format.

        */

        VertexData *sharedVertexData;

        /// replace the shared vertex data with a new one

        void resetVertexData(VertexData* data = nullptr)

        {

            delete sharedVertexData;

            sharedVertexData = data;

        }

        /// Creates a new shared vertex data object

        void createVertexData(HardwareBufferManagerBase* mgr = nullptr) { resetVertexData(new VertexData(mgr)); }

        /** Shared index map for translating blend index to bone index.

            This index map can be shared among multiple submeshes. SubMeshes might not have

            their own IndexMap, they might share this one.

        @par

            We collect actually used bones of all bone assignments, and build the

            blend index in 'packed' form, then the range of the blend index in vertex

            data VES_BLEND_INDICES element is continuous, with no gaps. Thus, by

            minimising the world matrix array constants passing to GPU, we can support

            more bones for a mesh when hardware skinning is used. The hardware skinning

            support limit is applied to each set of vertex data in the mesh, in other words, the

            hardware skinning support limit is applied only to the actually used bones of each

            SubMeshes, not all bones across the entire Mesh.

        @par

            Because the blend index is different to the bone index, therefore, we use

            the index map to translate the blend index to bone index.

        @par

            The use of shared or non-shared index map is determined when

            model data is converted to the OGRE .mesh format.

        */

        IndexMap sharedBlendIndexToBoneIndexMap;

        /** Makes a copy of this mesh object and gives it a new name.

            This is useful if you want to tweak an existing mesh without affecting the original one. The

            newly cloned mesh is registered with the MeshManager under the new name.

        @param newName

            The name to give the clone.

        @param newGroup

            Optional name of the new group to assign the clone to;

            if you leave this blank, the clone will be assigned to the same

            group as this Mesh.

        */

        MeshPtr clone(const String& newName, const String& newGroup = BLANKSTRING);

        /** @copydoc Resource::reload */

        void reload(LoadingFlags flags = LF_DEFAULT) override;

        /** Get the axis-aligned bounding box for this mesh.

        */

        const AxisAlignedBox& getBounds(void) const;

        /** Gets the radius of the bounding sphere surrounding this mesh. */

        Real getBoundingSphereRadius(void) const;

        /** Gets the radius used to inflate the bounding box around the bones. */

        Real getBoneBoundingRadius() const;

        /** Manually set the bounding box for this Mesh.

            Calling this method is required when building manual meshes now, because OGRE can no longer 

            update the bounds for you, because it cannot necessarily read vertex data back from 

            the vertex buffers which this mesh uses (they very well might be write-only, and even

            if they are not, reading data from a hardware buffer is a bottleneck).

            @param bounds The axis-aligned bounding box for this mesh

            @param pad If true, a certain padding will be added to the bounding box to separate it from the mesh

        */

        void _setBounds(const AxisAlignedBox& bounds, bool pad = true);

        /** Manually set the bounding radius. 

            Calling this method is required when building manual meshes now, because OGRE can no longer 

            update the bounds for you, because it cannot necessarily read vertex data back from 

            the vertex buffers which this mesh uses (they very well might be write-only, and even

            if they are not, reading data from a hardware buffer is a bottleneck).

        */

        void _setBoundingSphereRadius(Real radius);

        /** Manually set the bone bounding radius. 

            This value is normally computed automatically, however it can be overridden with this method.

        */

        void _setBoneBoundingRadius(Real radius);

        /** Compute the bone bounding radius by looking at the vertices, vertex-bone-assignments, and skeleton bind pose.

            This is automatically called by Entity if necessary.  Only does something if the boneBoundingRadius is zero to

            begin with.  Only works if vertex data is readable (i.e. not WRITE_ONLY).

        */

        void _computeBoneBoundingRadius();

        /** Automatically update the bounding radius and bounding box for this Mesh.

        Calling this method is required when building manual meshes. However it is recommended to

        use _setBounds and _setBoundingSphereRadius instead, because the vertex buffer may not have

        a shadow copy in the memory. Reading back the buffer from video memory is very slow!

        @param pad If true, a certain padding will be added to the bounding box to separate it from the mesh

        */

        void _updateBoundsFromVertexBuffers(bool pad = false);

        /** Calculates 

        Calling this method is required when building manual meshes. However it is recommended to

        use _setBounds and _setBoundingSphereRadius instead, because the vertex buffer may not have

        a shadow copy in the memory. Reading back the buffer from video memory is very slow!

        */

        void _calcBoundsFromVertexBuffer(VertexData* vertexData, AxisAlignedBox& outAABB, Real& outRadius, bool updateOnly = false);

        /** Sets the name of the skeleton this Mesh uses for animation.

            Meshes can optionally be assigned a skeleton which can be used to animate

            the mesh through bone assignments. The default is for the Mesh to use no

            skeleton. Calling this method with a valid skeleton filename will cause the

            skeleton to be loaded if it is not already (a single skeleton can be shared

            by many Mesh objects).

        @param skelName

            The name of the .skeleton file to use, or an empty string to use

            no skeleton

        */

        void setSkeletonName(const String& skelName);

        /** Returns true if this Mesh has a linked Skeleton. */

        bool hasSkeleton(void) const { return mSkeleton != 0; }

        /** Returns whether or not this mesh has some kind of vertex animation. 

        */

        bool hasVertexAnimation(void) const;

        /** Gets a pointer to any linked Skeleton. 

        @return

            Weak reference to the skeleton - copy this if you want to hold a strong pointer.

        */

        const SkeletonPtr& getSkeleton(void) const { return mSkeleton; }

        /** Gets the name of any linked Skeleton */

        const String& getSkeletonName(void) const;

        /** Initialise an animation set suitable for use with this mesh. 

            Only recommended for use inside the engine, not by applications.

        */

        void _initAnimationState(AnimationStateSet* animSet);

        /** Refresh an animation set suitable for use with this mesh. 

            Only recommended for use inside the engine, not by applications.

        */

        void _refreshAnimationState(AnimationStateSet* animSet);

        /** Assigns a vertex to a bone with a given weight, for skeletal animation. 

            This method is only valid after calling setSkeletonName.

            Since this is a one-off process there exists only 'addBoneAssignment' and

            'clearBoneAssignments' methods, no 'editBoneAssignment'. You should not need

            to modify bone assignments during rendering (only the positions of bones) and OGRE

            reserves the right to do some internal data reformatting of this information, depending

            on render system requirements.

        @par

            This method is for assigning weights to the shared geometry of the Mesh. To assign

            weights to the per-SubMesh geometry, see the equivalent methods on SubMesh.

        */

        void addBoneAssignment(const VertexBoneAssignment& vertBoneAssign);

        /** Removes all bone assignments for this mesh. 

            This method is for modifying weights to the shared geometry of the Mesh. To assign

            weights to the per-SubMesh geometry, see the equivalent methods on SubMesh.

        */

        void clearBoneAssignments(void);

        /** Internal notification, used to tell the Mesh which Skeleton to use without loading it. 

            This is only here for unusual situation where you want to manually set up a

            Skeleton. Best to let OGRE deal with this, don't call it yourself unless you

            really know what you're doing.

        */

        void _notifySkeleton(const SkeletonPtr& pSkel);

        /// @deprecated use getBoneAssignments

        OGRE_DEPRECATED BoneAssignmentIterator getBoneAssignmentIterator(void);

        /** Gets a const reference to the list of bone assignments

        */

        const VertexBoneAssignmentList& getBoneAssignments() const { return mBoneAssignments; }

        /** Returns the number of levels of detail that this mesh supports. 

            This number includes the original model.

        */

        ushort getNumLodLevels(void) const { return mNumLods; }

        /** Gets details of the numbered level of detail entry. */

        const MeshLodUsage& getLodLevel(ushort index) const;

        /** Retrieves the level of detail index for the given LOD value. 

        @note

            The value passed in is the 'transformed' value. If you are dealing with

            an original source value (e.g. distance), use LodStrategy::transformUserValue

            to turn this into a lookup value.

        */

        ushort getLodIndex(Real value) const;

        /** Returns true if this mesh has a manual LOD level.

            A mesh can either use automatically generated LOD, or it can use alternative

            meshes as provided by an artist.

        */

        bool hasManualLodLevel(void) const { return mHasManualLodLevel; }

#if !OGRE_NO_MESHLOD

        /** Changes the alternate mesh to use as a manual LOD at the given index.

            Note that the index of a LOD may change if you insert other LODs. If in doubt,

            use getLodIndex().

        @param index

            The index of the level to be changed.

        @param meshName

            The name of the mesh which will be the lower level detail version.

        */

        void updateManualLodLevel(ushort index, const String& meshName);

        /** Internal methods for loading LOD, do not use. */

        void _setLodInfo(unsigned short numLevels);

        /** Internal methods for loading LOD, do not use. */

        void _setLodUsage(unsigned short level, const MeshLodUsage& usage);

        /** Internal methods for loading LOD, do not use. */

        void _setSubMeshLodFaceList(unsigned short subIdx, unsigned short level, IndexData* facedata);

#endif

        /** Internal methods for loading LOD, do not use. */

        bool _isManualLodLevel(unsigned short level) const;

        /** Removes all LOD data from this Mesh. */

        void removeLodLevels(void);

        /** Sets the manager for the vertex and index buffers to be used when loading

            this Mesh.

        @param bufferManager

            If set to @ref DefaultHardwareBufferManager, the buffers will be created in system memory

            only, without hardware counterparts. Such mesh could not be rendered, but LODs could be

            generated for such mesh, it could be cloned, transformed and serialized.

        */

        void setHardwareBufferManager(HardwareBufferManagerBase* bufferManager) { mBufferManager = bufferManager; }

        HardwareBufferManagerBase* getHardwareBufferManager();

        /** Sets the policy for the vertex buffers to be used when loading

            this Mesh.

            By default, when loading the %Mesh, static, write-only vertex and index buffers

            will be used where possible in order to improve rendering performance. 

            However, such buffers

            cannot be manipulated on the fly by CPU code (although shader code can). If you

            wish to use the CPU to modify these buffers, you should call this method.

            @note This only takes effect after the Mesh has been reloaded. Also, you

            still have the option of manually replacing the buffers in this mesh with your

            own if you see fit too, in which case you don't need to call this method since it

            only affects buffers created by the mesh itself.

            You can define the approach to a %Mesh by changing the default parameters to

            MeshManager::load if you wish; this means the Mesh is loaded with those options

            the first time instead of you having to reload the mesh after changing these options.

        @param usage

            The usage flag, which by default is #HBU_GPU_ONLY

        @param shadowBuffer

            If set to @c true, the vertex buffers will be created with a

            system memory shadow buffer. You should set this if you want to be able to

            read from the buffer

        */

        void setVertexBufferPolicy(HardwareBuffer::Usage usage, bool shadowBuffer = false);

        /** Sets the policy for the index buffers to be used when loading

            this Mesh.

            @copydetails setVertexBufferPolicy

        */

        void setIndexBufferPolicy(HardwareBuffer::Usage usage, bool shadowBuffer = false);

        /** Gets the usage setting for this meshes vertex buffers. */

        HardwareBufferUsage getVertexBufferUsage(void) const { return mVertexBufferUsage; }

        /** Gets the usage setting for this meshes index buffers. */

        HardwareBufferUsage getIndexBufferUsage(void) const { return mIndexBufferUsage; }

        /** Gets whether or not this meshes vertex buffers are shadowed. */

        bool isVertexBufferShadowed(void) const { return mVertexBufferShadowBuffer; }

        /** Gets whether or not this meshes index buffers are shadowed. */

        bool isIndexBufferShadowed(void) const { return mIndexBufferShadowBuffer; }

        /** Rationalises the passed in bone assignment list.

            OGRE supports up to 4 bone assignments per vertex. The reason for this limit

            is that this is the maximum number of assignments that can be passed into

            a hardware-assisted blending algorithm. This method identifies where there are

            more than 4 bone assignments for a given vertex, and eliminates the bone

            assignments with the lowest weights to reduce to this limit. The remaining

            weights are then re-balanced to ensure that they sum to 1.0.

        @param vertexCount

            The number of vertices.

        @param assignments

            The bone assignment list to rationalise. This list will be modified and

            entries will be removed where the limits are exceeded.

        @return

            The maximum number of bone assignments per vertex found, clamped to [1-4]

        */

        unsigned short _rationaliseBoneAssignments(size_t vertexCount, VertexBoneAssignmentList& assignments);

        /** Internal method, be called once to compile bone assignments into geometry buffer. 

            The OGRE engine calls this method automatically. It compiles the information 

            submitted as bone assignments into a format usable in realtime. It also 

            eliminates excessive bone assignments (max is OGRE_MAX_BLEND_WEIGHTS)

            and re-normalises the remaining assignments.

        */

        void _compileBoneAssignments(void);

        /** Internal method, be called once to update the compiled bone assignments.

            The OGRE engine calls this method automatically. It updates the compiled bone

            assignments if requested.

        */

        void _updateCompiledBoneAssignments(void);

        /** This method collapses two texcoords into one for all submeshes where this is possible.

            Often a submesh can have two tex. coords. (i.e. TEXCOORD0 & TEXCOORD1), being both

            composed of two floats. There are many practical reasons why it would be more convenient

            to merge both of them into one TEXCOORD0 of 4 floats. This function does exactly that

            The finalTexCoordSet must have enough space for the merge, or else the submesh will be

            skipped. (i.e. you can't merge a tex. coord with 3 floats with one having 2 floats)

            finalTexCoordSet & texCoordSetToDestroy must be in the same buffer source, and must

            be adjacent.

        @param finalTexCoordSet The tex. coord index to merge to. Should have enough space to

            actually work.

        @param texCoordSetToDestroy The texture coordinate index that will disappear on

            successful merges.

        */

        void mergeAdjacentTexcoords( unsigned short finalTexCoordSet, unsigned short texCoordSetToDestroy );

        /** This method builds a set of tangent vectors for a given mesh into a 3D texture coordinate buffer.

            Tangent vectors are vectors representing the local 'X' axis for a given vertex based

            on the orientation of the 2D texture on the geometry. They are built from a combination

            of existing normals, and from the 2D texture coordinates already baked into the model.

            They can be used for a number of things, but most of all they are useful for 

            vertex and fragment programs, when you wish to arrive at a common space for doing

            per-pixel calculations.

        @par

            The prerequisites for calling this method include that the vertex data used by every

            SubMesh has both vertex normals and 2D texture coordinates.

        @param sourceTexCoordSet

            The texture coordinate index which should be used as the source

            of 2D texture coordinates, with which to calculate the tangents.

        @param splitMirrored

            Sets whether or not to split vertices when a mirrored tangent space

            transition is detected (matrix parity differs). @ref TangentSpaceCalc::setSplitMirrored

        @param splitRotated

            Sets whether or not to split vertices when a rotated tangent space

            is detected. @ref TangentSpaceCalc::setSplitRotated

        @param storeParityInW

            If @c true, store tangents as a 4-vector and include parity in w.

        */

        void buildTangentVectors(unsigned short sourceTexCoordSet = 0, bool splitMirrored = false,

                                 bool splitRotated = false, bool storeParityInW = false);

        /// @deprecated

        OGRE_DEPRECATED void buildTangentVectors(VertexElementSemantic targetSemantic,

                                                 unsigned short sourceTexCoordSet = 0, unsigned short index = 0,

                                                 bool splitMirrored = false, bool splitRotated = false,

                                                 bool storeParityInW = false)

        {

            OgreAssert(targetSemantic == VES_TANGENT && index == 0, "Invalid Parameters");

            buildTangentVectors(sourceTexCoordSet, splitMirrored, splitRotated, storeParityInW);

        }

        /** Ask the mesh to suggest a source texture coordinate set to a future buildTangentVectors call

            It will detect when there are inappropriate

            conditions (such as multiple geometry sets which don't agree).

        @param outSourceCoordSet

            Reference to a source texture coordinate set which

            will be used.

        @return @c true if it detects that tangents may have been prepared already.

        */

        bool suggestTangentVectorBuildParams(unsigned short& outSourceCoordSet);

        /// @deprecated

        OGRE_DEPRECATED bool suggestTangentVectorBuildParams(VertexElementSemantic targetSemantic,

                                                             unsigned short& outSourceCoordSet,

                                                             unsigned short& outIndex)

        {

            OgreAssert(targetSemantic == VES_TANGENT, "Invalid targetSemantic");

            outIndex = 0;

            return suggestTangentVectorBuildParams(outSourceCoordSet);

        }

        /** Builds an edge list for this mesh, which can be used for generating a shadow volume

            among other things.

        */

        void buildEdgeList(void);

        /** Destroys and frees the edge lists this mesh has built. */

        void freeEdgeList(void);

        /// @copydoc VertexData::prepareForShadowVolume

        void prepareForShadowVolume(void);

        /** Return the edge list for this mesh, building it if required. 

            You must ensure that the Mesh as been prepared for shadow volume 

            rendering if you intend to use this information for that purpose.

        @param lodIndex

            The LOD at which to get the edge list, 0 being the highest.

        */

        EdgeData* getEdgeList(unsigned short lodIndex = 0);

        /** Return the edge list for this mesh, building it if required. 

            You must ensure that the Mesh as been prepared for shadow volume 

            rendering if you intend to use this information for that purpose.

        @param lodIndex

            The LOD at which to get the edge list, 0 being the highest.

        */

        const EdgeData* getEdgeList(unsigned short lodIndex = 0) const;

        /** Returns whether this mesh has already had it's geometry prepared for use in 

            rendering shadow volumes. */

        bool isPreparedForShadowVolumes(void) const { return mPreparedForShadowVolumes; }

        /** Returns whether this mesh has an attached edge list. */

        bool isEdgeListBuilt(void) const { return mEdgeListsBuilt; }

        /** Prepare matrices for software indexed vertex blend.

            This function organise bone indexed matrices to blend indexed matrices,

            so software vertex blending can access to the matrix via blend index

            directly.

        @param blendMatrices

            Pointer to an array of matrix pointers to store

            prepared results, which indexed by blend index.

        @param boneMatrices

            Pointer to an array of matrices to be used to blend,

            which indexed by bone index.

        @param indexMap

            The index map used to translate blend index to bone index.

        */

        static void prepareMatricesForVertexBlend(const Affine3** blendMatrices,

            const Affine3* boneMatrices, const IndexMap& indexMap);

        /** Performs a software indexed vertex blend, of the kind used for

            skeletal animation although it can be used for other purposes. 

            This function is supplied to update vertex data with blends 

            done in software, either because no hardware support is available, 

            or that you need the results of the blend for some other CPU operations.

        @param sourceVertexData

            VertexData class containing positions, normals,

            blend indices and blend weights.

        @param targetVertexData

            VertexData class containing target position

            and normal buffers which will be updated with the blended versions.

            Note that the layout of the source and target position / normal 

            buffers must be identical, ie they must use the same buffer indexes

        @param blendMatrices

            Pointer to an array of matrix pointers to be used to blend,

            indexed by blend indices in the sourceVertexData

        @param numMatrices

            Number of matrices in the blendMatrices, it might be used

            as a hint for optimisation.

        @param blendNormals

            If @c true, normals are blended as well as positions.

        */

        static void softwareVertexBlend(const VertexData* sourceVertexData, 

            const VertexData* targetVertexData,

            const Affine3* const* blendMatrices, size_t numMatrices,

            bool blendNormals);

        /** Performs a software vertex morph, of the kind used for

            morph animation although it can be used for other purposes. 

            This function will linearly interpolate positions between two

            source buffers, into a third buffer.

        @param t

            Parametric distance between the start and end buffer positions.

        @param b1

            Vertex buffer containing VET_FLOAT3 entries for the start positions.

        @param b2

            Vertex buffer containing VET_FLOAT3 entries for the end positions.

        @param targetVertexData

            VertexData destination; assumed to have a separate position

            buffer already bound, and the number of vertices must agree with the

            number in start and end

        */

        static void softwareVertexMorph(float t,

            const HardwareVertexBufferSharedPtr& b1, 

            const HardwareVertexBufferSharedPtr& b2, 

            VertexData* targetVertexData);

        /** Performs a software vertex pose blend, of the kind used for

            morph animation although it can be used for other purposes. 

            This function will apply a weighted offset to the positions in the 

            incoming vertex data (therefore this is a read/write operation, and 

            if you expect to call it more than once with the same data, then

            you would be best to suppress hardware uploads of the position buffer

            for the duration).

        @param weight

            Parametric weight to scale the offsets by.

        @param vertexOffsetMap

            Potentially sparse map of vertex index -> offset.

        @param normalsMap

            Potentially sparse map of vertex index -> normal.

        @param targetVertexData 

            VertexData destination; assumed to have a separate position

            buffer already bound, and the number of vertices must agree with the

            number in start and end.

        */

        static void softwareVertexPoseBlend(float weight,

            const std::map<uint32, Vector3f>& vertexOffsetMap,

            const std::map<uint32, Vector3f>& normalsMap,

            VertexData* targetVertexData);

        /** Gets a reference to the optional name assignments of the SubMeshes. */

        const SubMeshNameMap& getSubMeshNameMap(void) const { return mSubMeshNameMap; }

        /** Sets whether or not this Mesh should automatically build edge lists

            when asked for them, or whether it should never build them if

            they are not already provided.

            This allows you to create meshes which do not have edge lists calculated, 

            because you never want to use them. This value defaults to 'true'

            for mesh formats which did not include edge data, and 'false' for 

            newer formats, where edge lists are expected to have been generated

            in advance.

        */

        void setAutoBuildEdgeLists(bool autobuild) { mAutoBuildEdgeLists = autobuild; }

        /** Sets whether or not this Mesh should automatically build edge lists

            when asked for them, or whether it should never build them if

            they are not already provided.

        */

        bool getAutoBuildEdgeLists(void) const { return mAutoBuildEdgeLists; }

        /** Gets the type of vertex animation the shared vertex data of this mesh supports.

        */

        virtual VertexAnimationType getSharedVertexDataAnimationType(void) const;

        /// Returns whether animation on shared vertex data includes normals.

        bool getSharedVertexDataAnimationIncludesNormals() const { return mSharedVertexDataAnimationIncludesNormals; }

        Animation* createAnimation(const String& name, Real length) override;

        Animation* getAnimation(const String& name) const override;

        /** Internal access to the named vertex Animation object - returns null 

            if it does not exist. 

        @param name

            The name of the animation.

        */

        virtual Animation* _getAnimationImpl(const String& name) const;

        bool hasAnimation(const String& name) const override;

        void removeAnimation(const String& name) override;

        unsigned short getNumAnimations(void) const override;

        Animation* getAnimation(unsigned short index) const override;

        /** Removes all morph Animations from this mesh. */

        virtual void removeAllAnimations(void);

        /** Gets a pointer to a vertex data element based on a morph animation 

            track handle.

            0 means the shared vertex data, 1+ means a submesh vertex data (index+1)

        */

        VertexData* getVertexDataByTrackHandle(unsigned short handle);

        /** Internal method which, if animation types have not been determined,

            scans any vertex animations and determines the type for each set of

            vertex data (cannot have 2 different types).

        */

        void _determineAnimationTypes(void) const;

        /** Are the derived animation types out of date? */

        bool _getAnimationTypesDirty(void) const { return mAnimationTypesDirty; }

        /** Create a new Pose for this mesh or one of its submeshes.

        @param target

            The target geometry index; 0 is the shared Mesh geometry, 1+ is the

            dedicated SubMesh geometry belonging to submesh index + 1.

        @param name

            Name to give the pose, which is optional.

        @return

            A new Pose ready for population.

        */

        Pose* createPose(ushort target, const String& name = BLANKSTRING);

        /** Get the number of poses */

        size_t getPoseCount(void) const { return mPoseList.size(); }

        /** Retrieve an existing Pose by index */

        Pose* getPose(size_t index) const { return mPoseList.at(index); }

        /** Retrieve an existing Pose by name.*/

        Pose* getPose(const String& name) const;

        /** Destroy a pose by index.

        @note

            This will invalidate any animation tracks referring to this pose or those after it.

        */

        void removePose(ushort index);

        /** Destroy a pose by name.

        @note

            This will invalidate any animation tracks referring to this pose or those after it.

        */

        void removePose(const String& name);

        /** Destroy all poses. */

        void removeAllPoses(void);

        typedef VectorIterator<PoseList> PoseIterator;

        typedef ConstVectorIterator<PoseList> ConstPoseIterator;

        /** Get an iterator over all the poses defined.

         * @deprecated use getPoseList() */

        OGRE_DEPRECATED PoseIterator getPoseIterator(void);

        /** Get an iterator over all the poses defined.

         * @deprecated use getPoseList()  */

        OGRE_DEPRECATED ConstPoseIterator getPoseIterator(void) const;

        /** Get pose list. */

        const PoseList& getPoseList(void) const;

        /** Get LOD strategy used by this mesh. */

        const LodStrategy *getLodStrategy() const;

#if !OGRE_NO_MESHLOD

        /** Set the lod strategy used by this mesh. */

        void setLodStrategy(LodStrategy *lodStrategy);

#endif

        void _convertVertexElement(VertexElementSemantic semantic, VertexElementType dstType);

        /// @copydoc UserObjectBindings

        UserObjectBindings& getUserObjectBindings() { return mUserObjectBindings; }

        /// @overload

        const UserObjectBindings& getUserObjectBindings() const { return mUserObjectBindings; }

    };

    /** A way of recording the way each LODs is recorded this Mesh. */

    struct MeshLodUsage

    {

        /** User-supplied values used to determine on which distance the lod is applies.

            This is required in case the LOD strategy changes.

        */

        Real userValue;

        /** Value used by to determine when this LOD applies.

            May be interpreted differently by different strategies.

            Transformed from user-supplied values with LodStrategy::transformUserValue.

        */

        Real value;

        /// Only relevant if mIsLodManual is true, the name of the alternative mesh to use.

        String manualName;

        /// Hard link to mesh to avoid looking up each time.

        mutable MeshPtr manualMesh;

        /// Edge list for this LOD level (may be derived from manual mesh).

        mutable EdgeData* edgeData;

        MeshLodUsage() : userValue(0.0), value(0.0), edgeData(0) {}

    };

    /** @} */

    /** @} */

} // namespace Ogre

#include "OgreHeaderSuffix.h"

#endif // __Mesh_H__