/*

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

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.

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*/

#ifndef __Skeleton_H__

#define __Skeleton_H__

#include "OgrePrerequisites.h"

#include "OgreResource.h"

#include "OgreStringVector.h"

#include "OgreAnimation.h"

#include "OgreHeaderPrefix.h"

#include "OgreSharedPtr.h"

namespace Ogre {

    /** \addtogroup Core

    *  @{

    */

    /** \addtogroup Animation

    *  @{

    */

    /**  */

    enum SkeletonAnimationBlendMode : uint8 {

        /// Animations are applied by calculating a weighted average of all animations

        ANIMBLEND_AVERAGE = 0,

        /// Animations are applied by calculating a weighted cumulative total

        ANIMBLEND_CUMULATIVE = 1

    };

    struct LinkedSkeletonAnimationSource;

    /** A collection of Bone objects used to animate a skinned mesh.

        Skeletal animation works by having a collection of 'bones' which are 

        actually just joints with a position and orientation, arranged in a tree structure.

        For example, the wrist joint is a child of the elbow joint, which in turn is a

        child of the shoulder joint. Rotating the shoulder automatically moves the elbow

        and wrist as well due to this hierarchy.

    @par

        So how does this animate a mesh? Well every vertex in a mesh is assigned to one or more

        bones which affects it's position when the bone is moved. If a vertex is assigned to 

        more than one bone, then weights must be assigned to determine how much each bone affects

        the vertex (actually a weight of 1.0 is used for single bone assignments). 

        Weighted vertex assignments are especially useful around the joints themselves

        to avoid 'pinching' of the mesh in this region. 

    @par

        Therefore by moving the skeleton using preset animations, we can animate the mesh. The

        advantage of using skeletal animation is that you store less animation data, especially

        as vertex counts increase. In addition, you are able to blend multiple animations together

        (e.g. walking and looking around, running and shooting) and provide smooth transitions

        between animations without incurring as much of an overhead as would be involved if you

        did this on the core vertex data.

    @par

        Skeleton definitions are loaded from datafiles, namely the .skeleton file format. They

        are loaded on demand, especially when referenced by a Mesh.

    */

    class _OgreExport Skeleton : public Resource, public AnimationContainer

    {

        friend class SkeletonInstance;

    private:

        /// Internal constructor for use by SkeletonInstance only

        Skeleton();

    public:

        /** Constructor, don't call directly, use SkeletonManager.

            On creation, a Skeleton has a no bones, you should create them and link

            them together appropriately. 

        */

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

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

        virtual ~Skeleton();

        /** Creates a brand new Bone owned by this Skeleton. 

            This method creates an unattached new Bone for this skeleton.

            Unless this is to be a root bone (there may be more than one of 

            these), you must attach it to another Bone in the skeleton using addChild for it to be any use.

            For this reason you will likely be better off creating child bones using the

            Bone::createChild method instead, once you have created the root bone. 

        @par

            Note that this method automatically generates a handle for the bone, which you

            can retrieve using Bone::getHandle. If you wish the new Bone to have a specific

            handle, use the alternate form of this method which takes a handle as a parameter,

            although you should note the restrictions.

        */

        virtual Bone* createBone(void);

        /** Creates a brand new Bone owned by this Skeleton. 

            This method creates an unattached new Bone for this skeleton and assigns it a 

            specific handle. Unless this is to be a root bone (there may be more than one of 

            these), you must attach it to another Bone in the skeleton using addChild for it to be any use. 

            For this reason you will likely be better off creating child bones using the

            Bone::createChild method instead, once you have created a root bone. 

        @param handle The handle to give to this new bone - must be unique within this skeleton. 

            You should also ensure that all bone handles are eventually contiguous (this is to simplify

            their compilation into an indexed array of transformation matrices). For this reason

            it is advised that you use the simpler createBone method which automatically assigns a

            sequential handle starting from 0.

        */

        virtual Bone* createBone(unsigned short handle);

        /** Creates a brand new Bone owned by this Skeleton. 

            This method creates an unattached new Bone for this skeleton and assigns it a 

            specific name.Unless this is to be a root bone (there may be more than one of 

            these), you must attach it to another Bone in the skeleton using addChild for it to be any use.

            For this reason you will likely be better off creating child bones using the

            Bone::createChild method instead, once you have created the root bone. 

        @param name The name to give to this new bone - must be unique within this skeleton. 

            Note that the way OGRE looks up bones is via a numeric handle, so if you name a

            Bone this way it will be given an automatic sequential handle. The name is just

            for your convenience, although it is recommended that you only use the handle to 

            retrieve the bone in performance-critical code.

        */

        virtual Bone* createBone(const String& name);

        /** Creates a brand new Bone owned by this Skeleton. 

            This method creates an unattached new Bone for this skeleton and assigns it a 

            specific name and handle. Unless this is to be a root bone (there may be more than one of 

            these), you must attach it to another Bone in the skeleton using addChild for it to be any use.

            For this reason you will likely be better off creating child bones using the

            Bone::createChild method instead, once you have created the root bone. 

        @param name The name to give to this new bone - must be unique within this skeleton. 

        @param handle The handle to give to this new bone - must be unique within this skeleton. 

        */

        virtual Bone* createBone(const String& name, unsigned short handle);

        /** Returns the number of bones in this skeleton. */

        unsigned short getNumBones(void) const { return (unsigned short)mBoneList.size(); }

        typedef std::vector<Bone*> BoneList;

        typedef VectorIterator<BoneList> BoneIterator;

        /// Get an iterator over the root bones in the skeleton, ie those with no parents

        /// @deprecated use Skeleton::getRootBones

        OGRE_DEPRECATED virtual BoneIterator getRootBoneIterator(void);

        /** Get the root bones in the skeleton, ie those with no parents

            The system derives the root bone the first time you ask for it. The root bone is the

            only bone in the skeleton which has no parent. The system locates it by taking the

            first bone in the list and going up the bone tree until there are no more parents,

            and saves this top bone as the root. If you are building the skeleton manually using

            createBone then you must ensure there is only one bone which is not a child of

            another bone, otherwise your skeleton will not work properly. If you use createBone

            only once, and then use Bone::createChild from then on, then inherently the first

            bone you create will by default be the root.

        */

        const BoneList& getRootBones() const;

        /// Get an iterator over all the bones in the skeleton

        /// @deprecated use getBones()

        OGRE_DEPRECATED virtual BoneIterator getBoneIterator(void);

        /// Get all the bones in the skeleton

        const BoneList& getBones() const {

            return mBoneList;

        }

        /** Gets a bone by it's handle. */

        Bone* getBone(unsigned short handle) const

        {

            assert(handle < mBoneList.size() && "Index out of bounds");

            return mBoneList[handle];

        }

        /** Gets a bone by it's name. */

        Bone* getBone(const String& name) const;

        /** Returns whether this skeleton contains the named bone. */

        bool hasBone(const String& name) const;

        /** Sets the current position / orientation to be the 'binding pose' i.e. the layout in which 

            bones were originally bound to a mesh.

        */

        void setBindingPose(void);

        /** Resets the position and orientation of all bones in this skeleton to their original binding position.

            A skeleton is bound to a mesh in a binding pose. Bone positions are then modified from this

            position during animation. This method returns all the bones to their original position and

            orientation.

        @param resetManualBones If set to true, causes the state of manual bones to be reset

            too, which is normally not done to allow the manual state to persist even 

            when keyframe animation is applied.

        */

        void reset(bool resetManualBones = false);

        /** Creates a new Animation object for animating this skeleton. 

        @copydetails AnimationContainer::createAnimation

        */

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

        /** Returns the named Animation object. 

            Will pick up animations in linked skeletons 

            (@see addLinkedSkeletonAnimationSource). 

        @param name The name of the animation

        @param linker Optional pointer to a pointer to the linked skeleton animation

            where this is coming from.

        */

        virtual Animation* getAnimation(const String& name, 

            const LinkedSkeletonAnimationSource** linker) const;

        /** Returns the named Animation object.

             Will pick up animations in linked skeletons 

             (@see addLinkedSkeletonAnimationSource). 

         @param name The name of the animation

         */

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

        /// Internal accessor for animations (returns null if animation does not exist)

        virtual Animation* _getAnimationImpl(const String& name, 

            const LinkedSkeletonAnimationSource** linker = 0) const;

        bool hasAnimation(const String& name) const override;

        void removeAnimation(const String& name) override;

        /** Changes the state of the skeleton to reflect the application of the passed in collection of animations.

            Animating a skeleton involves both interpolating between keyframes of a specific animation,

            and blending between the animations themselves. Calling this method sets the state of

            the skeleton so that it reflects the combination of all the passed in animations, at the

            time index specified for each, using the weights specified. Note that the weights between 

            animations do not have to sum to 1.0, because some animations may affect only subsets

            of the skeleton. If the weights exceed 1.0 for the same area of the skeleton, the 

            movement will just be exaggerated.

        */

        virtual void setAnimationState(const AnimationStateSet& animSet);

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

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

        */

        virtual void _initAnimationState(AnimationStateSet* animSet);

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

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

        */

        virtual void _refreshAnimationState(AnimationStateSet* animSet);

        /** Populates the passed in array with the bone matrices based on the current position.

            Internal use only. The array pointed to by the passed in pointer must

            be at least as large as the number of bones.

            Assumes animation has already been updated.

        */

        void _getBoneMatrices(Affine3* pMatrices);

        unsigned short getNumAnimations(void) const override;

        /** Gets a single animation by index. 

            Will NOT pick up animations in linked skeletons 

            (@see addLinkedSkeletonAnimationSource).

        */

        Animation* getAnimation(unsigned short index) const override;

        /** Gets the animation blending mode which this skeleton will use. */

        SkeletonAnimationBlendMode getBlendMode() const { return mBlendState; }

        /** Sets the animation blending mode this skeleton will use. */

        void setBlendMode(SkeletonAnimationBlendMode state) { mBlendState = state; }

        /// Updates all the derived transforms in the skeleton

        virtual void _updateTransforms(void);

        /** Optimise all of this skeleton's animations.

        @see Animation::optimise

        @param

            preservingIdentityNodeTracks If true, don't destroy identity node tracks.

        */

        virtual void optimiseAllAnimations(bool preservingIdentityNodeTracks = false);

        /** Allows you to use the animations from another Skeleton object to animate

            this skeleton.

            If you have skeletons of identical structure (that means identically

            named bones with identical handles, and with the same hierarchy), but

            slightly different proportions or binding poses, you can re-use animations

            from one in the other. Because animations are actually stored as

            changes to bones from their bind positions, it's possible to use the

            same animation data for different skeletons, provided the skeletal

            structure matches and the 'deltas' stored in the keyframes apply

            equally well to the other skeletons bind position (so they must be

            roughly similar, but don't have to be identical). You can use the 

            'scale' option to adjust the translation and scale keyframes where

            there are large differences in size between the skeletons.

        @note

            This method takes a skeleton name, rather than a more specific 

            animation name, for two reasons; firstly it allows some validation 

            of compatibility of skeletal structure, and secondly skeletons are

            the unit of loading. Linking a skeleton to another in this way means

            that the linkee will be prevented from being destroyed until the 

            linker is destroyed.

            You cannot set up cyclic relationships, e.g. SkeletonA uses SkeletonB's

            animations, and SkeletonB uses SkeletonA's animations. This is because

            it would set up a circular dependency which would prevent proper 

            unloading - make one of the skeletons the 'master' in this case.

        @param skelName Name of the skeleton to link animations from. This 

            skeleton will be loaded immediately if this skeleton is already 

            loaded, otherwise it will be loaded when this skeleton is.

        @param scale A scale factor to apply to translation and scaling elements

            of the keyframes in the other skeleton when applying the animations

            to this one. Compensates for skeleton size differences.

        */

        virtual void addLinkedSkeletonAnimationSource(const String& skelName, 

            Real scale = 1.0f);

        /// Remove all links to other skeletons for the purposes of sharing animation

        virtual void removeAllLinkedSkeletonAnimationSources(void);

        typedef std::vector<LinkedSkeletonAnimationSource> 

            LinkedSkeletonAnimSourceList;

        typedef ConstVectorIterator<LinkedSkeletonAnimSourceList> 

            LinkedSkeletonAnimSourceIterator;

        /// Get the linked skeletons used as animation sources

        virtual const LinkedSkeletonAnimSourceList& getLinkedSkeletonAnimationSources() const

        {

            return mLinkedSkeletonAnimSourceList;

        }

        /// @deprecated use getLinkedSkeletonAnimationSources

        OGRE_DEPRECATED virtual LinkedSkeletonAnimSourceIterator

            getLinkedSkeletonAnimationSourceIterator(void) const;

        /// Internal method for marking the manual bones as dirty

        virtual void _notifyManualBonesDirty(void);

        /// Internal method for notifying that a bone is manual

        virtual void _notifyManualBoneStateChange(Bone* bone);

        /// Have manual bones been modified since the skeleton was last updated?

        virtual bool getManualBonesDirty(void) const { return mManualBonesDirty; }

        /// Are there any manually controlled bones?

        virtual bool hasManualBones(void) const { return !mManualBones.empty(); }

        /// Map to translate bone handle from one skeleton to another skeleton.

        typedef std::vector<ushort> BoneHandleMap;

        /** Merge animations from another Skeleton object into this skeleton.

            This function allow merge two structures compatible skeletons. The

            'compatible' here means identically bones will have same hierarchy,

            but skeletons are not necessary to have same number of bones (if

            number bones of source skeleton's more than this skeleton, they will

            copied as is, except that duplicate names are disallowed; and in the

            case of bones missing in source skeleton, nothing happen for those

            bones).

        @par

            There are also unnecessary to have same binding poses, this function

            will adjust keyframes of the source skeleton to match this skeleton

            automatically.

        @par

            It's useful for exporting skeleton animations separately. i.e. export

            mesh and 'master' skeleton at the same time, and then other animations

            will export separately (even if used completely difference binding

            pose), finally, merge separately exported animations into 'master'

            skeleton.

        @param

            source Pointer to source skeleton. It'll keep unmodified.

        @param

            boneHandleMap A map to translate identically bone's handle from source

            skeleton to this skeleton. If mapped bone handle doesn't exists in this

            skeleton, it'll created. You can populate bone handle map manually, or

            use predefined functions build bone handle map for you. (@see 

            _buildMapBoneByHandle, _buildMapBoneByName)

        @param

            animations A list name of animations to merge, if empty, all animations

            of source skeleton are used to merge. Note that the animation names

            must not presented in this skeleton, and will NOT pick up animations

            in linked skeletons (@see addLinkedSkeletonAnimationSource).

        */

        virtual void _mergeSkeletonAnimations(const Skeleton* source,

            const BoneHandleMap& boneHandleMap,

            const StringVector& animations = StringVector());

        /** Build the bone handle map to use with Skeleton::_mergeSkeletonAnimations.

            Identically bones are determine by handle.

        */

        virtual void _buildMapBoneByHandle(const Skeleton* source,

            BoneHandleMap& boneHandleMap) const;

        /** Build the bone handle map to use with Skeleton::_mergeSkeletonAnimations.

            Identically bones are determine by name.

        */

        virtual void _buildMapBoneByName(const Skeleton* source,

            BoneHandleMap& boneHandleMap) const;

    protected:

        /// Storage of animations, lookup by name

        AnimationList mAnimationsList;

    private:

        /// Lookup by bone name

        typedef std::map<String, Bone*> BoneListByName;

        BoneListByName mBoneListByName;

        /// Pointer to root bones (can now have multiple roots)

        mutable BoneList mRootBones;

        typedef std::set<Bone*> BoneSet;

        /// Manual bones

        BoneSet mManualBones;

        /// List of references to other skeletons to use animations from 

        mutable LinkedSkeletonAnimSourceList mLinkedSkeletonAnimSourceList;

        SkeletonAnimationBlendMode mBlendState;

        /// Manual bones dirty?

        bool mManualBonesDirty;

        /// Storage of bones, indexed by bone handle

        BoneList mBoneList;

        /** Internal method which parses the bones to derive the root bone. 

            Must be const because called in getRootBone but mRootBone is mutable

            since lazy-updated.

        */

        void deriveRootBone(void) const;

        /// Debugging method

        _OgreExport friend std::ostream& operator<<(std::ostream& o, const Skeleton& s);

        void loadImpl() override {}

        void unloadImpl() override { unprepareImpl(); }

        void prepareImpl(void) override;

        void unprepareImpl(void) override;

        /// @copydoc Resource::calculateSize

        size_t calculateSize(void) const override;

    };

    /// Link to another skeleton to share animations

    struct LinkedSkeletonAnimationSource

    {

        String skeletonName;

        SkeletonPtr pSkeleton;

        Real scale;

        LinkedSkeletonAnimationSource(const String& skelName, Real scl)

            : skeletonName(skelName), scale(scl) {}

            LinkedSkeletonAnimationSource(const String& skelName, Real scl, 

                const SkeletonPtr& skelPtr)

                : skeletonName(skelName), pSkeleton(skelPtr), scale(scl) {}

    };

    /** @} */

    /** @} */

}

#include "OgreHeaderSuffix.h"

#endif