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Open Asset Import Library (ASSIMP)
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*/

/** @file SceneAnimator.h 
 *  Manages animations for a given scene and calculates present
 *  transformations for all nodes 
 */

#ifndef AV_SCENEANIMATOR_H_INCLUDED
#define AV_SCENEANIMATOR_H_INCLUDED

#include <map>

namespace AssimpView	{

// ---------------------------------------------------------------------------------
/** A little tree structure to match the scene's node structure, but holding 
 *  additional data. Needs to be public to allow using it in templates at 
 *  certain compilers.
 */
struct SceneAnimNode
{
	std::string mName;
	SceneAnimNode* mParent;
	std::vector<SceneAnimNode*> mChildren;

	//! most recently calculated local transform
	aiMatrix4x4 mLocalTransform; 

	//! same, but in world space
	aiMatrix4x4 mGlobalTransform;

	//!  index in the current animation's channel array. -1 if not animated.
	size_t mChannelIndex;        

	//! Default construction
	SceneAnimNode() {
		mChannelIndex = -1; mParent = NULL; 
	}

	//! Construction from a given name
	SceneAnimNode( const std::string& pName) 
		: mName( pName) { 
			mChannelIndex = -1; mParent = NULL;
	}

	//! Destruct all children recursively
	~SceneAnimNode() {
		for( std::vector<SceneAnimNode*>::iterator it = mChildren.begin(); it != mChildren.end(); ++it)
			delete *it; 
	}
};

// ---------------------------------------------------------------------------------
/** Calculates the animated node transformations for a given scene and timestamp. 
 *
 *  Create an instance for a aiScene you want to animate and set the current animation 
 *  to play. You can then have the instance calculate the current pose for all nodes 
 *  by calling Calculate() for a given timestamp. After this you can retrieve the 
 *  present transformation for a given node by calling GetLocalTransform() or
 *  GetGlobalTransform(). A full set of bone matrices can be retrieved by 
 *  GetBoneMatrices() for a given mesh. 
 */
class SceneAnimator
{
public:

	// ----------------------------------------------------------------------------
	/** Constructor for a given scene.
	 *
	 * The object keeps a reference to the scene during its lifetime, but 
	 * ownership stays at the caller. 
	 * @param pScene The scene to animate.
	 * @param pAnimIndex [optional] Index of the animation to play. Assumed to
	 *  be 0 if not given.
	 */
	SceneAnimator( const aiScene* pScene, size_t pAnimIndex = 0);

	/** Destructor */
	~SceneAnimator();

	// ----------------------------------------------------------------------------
	/** Sets the animation to use for playback. This also recreates the internal 
	 * mapping structures, which might take a few cycles.
	 * @param pAnimIndex Index of the animation in the scene's animation array 
	 */
	void SetAnimIndex( size_t pAnimIndex);

	// ----------------------------------------------------------------------------
	/** Calculates the node transformations for the scene. Call this to get 
	 * uptodate results before calling one of the getters.
	 * @param pTime Current time. Can be an arbitrary range.
	 */
	void Calculate( double pTime);

	// ----------------------------------------------------------------------------
	/** Retrieves the most recent local transformation matrix for the given node. 
	 * 
	 * The returned matrix is in the node's parent's local space, just like the 
	 * original node's transformation matrix. If the node is not animated, the
	 * node's original transformation is returned so that you can safely use or 
	 * assign it to the node itsself. If there is no node with the given name, 
	 * the identity matrix is returned. All transformations are updated whenever
	 * Calculate() is called.
	 * @param pNodeName Name of the node
	 * @return A reference to the node's most recently calculated local 
	 *   transformation matrix.
	 */
	const aiMatrix4x4& GetLocalTransform( const aiNode* node) const; 

	// ----------------------------------------------------------------------------
	/** Retrieves the most recent global transformation matrix for the given node.
	 *
	 * The returned matrix is in world space, which is the same coordinate space 
	 * as the transformation of the scene's root node. If the node is not animated, 
	 * the node's original transformation is returned so that you can safely use or 
	 * assign it to the node itsself. If there is no node with the given name, the 
	 * identity matrix is returned. All transformations are updated whenever 
	 * Calculate() is called.
	 * @param pNodeName Name of the node
	 * @return A reference to the node's most recently calculated global 
	 *   transformation matrix.
	 */
	const aiMatrix4x4& GetGlobalTransform( const aiNode* node) const;

	// ----------------------------------------------------------------------------
	/** Calculates the bone matrices for the given mesh.
	 *
	 * Each bone matrix transforms from mesh space in bind pose to mesh space in 
	 * skinned pose, it does not contain the mesh's world matrix. Thus the usual
	 * matrix chain for using in the vertex shader is
	 * @code
	 * boneMatrix * worldMatrix * viewMatrix * projMatrix
	 * @endcode
	 * @param pNode The node carrying the mesh.
	 * @param pMeshIndex Index of the mesh in the node's mesh array. The NODE's
	 *   mesh array, not  the scene's mesh array! Leave out to use the first mesh
	 *   of the node, which is usually also the only one.
	 * @return A reference to a vector of bone matrices. Stays stable till the
	 *   next call to GetBoneMatrices();
	 */
	const std::vector<aiMatrix4x4>& GetBoneMatrices( const aiNode* pNode, 
		size_t pMeshIndex = 0);


	// ----------------------------------------------------------------------------
	/** @brief Get the current animation index
	 */
	size_t CurrentAnimIndex() const {
		return mCurrentAnimIndex;
	}

	// ----------------------------------------------------------------------------
	/** @brief Get the current animation or NULL
	 */
	aiAnimation* CurrentAnim() const {
		return  mCurrentAnimIndex < mScene->mNumAnimations ? mScene->mAnimations[ mCurrentAnimIndex ] : NULL;
	}

protected:

	/** Recursively creates an internal node structure matching the 
	 *  current scene and animation. 
	 */
	SceneAnimNode* CreateNodeTree( aiNode* pNode, SceneAnimNode* pParent);

	/** Recursively updates the internal node transformations from the
	 *  given matrix array 
	 */
	void UpdateTransforms( SceneAnimNode* pNode, const std::vector<aiMatrix4x4>& pTransforms);

	/** Calculates the global transformation matrix for the given internal node */
	void CalculateGlobalTransform( SceneAnimNode* pInternalNode);

protected:
	/** The scene we're operating on */
	const aiScene* mScene;

	/** Current animation index */
	size_t mCurrentAnimIndex;

	/** The AnimEvaluator we use to calculate the current pose for the current animation */
	AnimEvaluator* mAnimEvaluator;

	/** Root node of the internal scene structure */
	SceneAnimNode* mRootNode;

	/** Name to node map to quickly find nodes by their name */
	typedef std::map<const aiNode*, SceneAnimNode*> NodeMap;
	NodeMap mNodesByName;

	/** Name to node map to quickly find nodes for given bones by their name */
	typedef std::map<const char*, const aiNode*> BoneMap;
	BoneMap mBoneNodesByName;

	/** Array to return transformations results inside. */
	std::vector<aiMatrix4x4> mTransforms;

	/** Identity matrix to return a reference to in case of error */
	aiMatrix4x4 mIdentityMatrix;
};

} // end of namespace AssimpView

#endif // AV_SCENEANIMATOR_H_INCLUDED