/*
---------------------------------------------------------------------------
Open Asset Import Library (ASSIMP)
---------------------------------------------------------------------------

Copyright (c) 2006-2010, ASSIMP Development Team

All rights reserved.

Redistribution and use of this software in source and binary forms, 
with or without modification, are permitted provided that the following 
conditions are met:

* Redistributions of source code must retain the above
  copyright notice, this list of conditions and the
  following disclaimer.

* Redistributions in binary form must reproduce the above
  copyright notice, this list of conditions and the
  following disclaimer in the documentation and/or other
  materials provided with the distribution.

* Neither the name of the ASSIMP team, nor the names of its
  contributors may be used to endorse or promote products
  derived from this software without specific prior
  written permission of the ASSIMP Development Team.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
---------------------------------------------------------------------------
*/

/** @file SceneAnimator.cpp
 *  @brief Implementation of the utility class SceneAnimator
 */

#include "stdafx.h"
#include "assimp_view.h"

using namespace AssimpView;

// ------------------------------------------------------------------------------------------------
// Constructor for a given scene.
SceneAnimator::SceneAnimator( const aiScene* pScene, size_t pAnimIndex)
{
	mScene = pScene;
	mCurrentAnimIndex = -1;
	mAnimEvaluator = NULL;
	mRootNode = NULL;

	// build the nodes-for-bones table
	for (unsigned int i = 0; i < pScene->mNumMeshes;++i)
	{
		const aiMesh* mesh = pScene->mMeshes[i];
		for (unsigned int n = 0; n < mesh->mNumBones;++n)
		{
			const aiBone* bone = mesh->mBones[n];

			mBoneNodesByName[bone->mName.data] = pScene->mRootNode->FindNode(bone->mName);
		}
	}

	// changing the current animation also creates the node tree for this animation
	SetAnimIndex( pAnimIndex);
}

// ------------------------------------------------------------------------------------------------
// Destructor
SceneAnimator::~SceneAnimator()
{
	delete mRootNode;
	delete mAnimEvaluator;
}

// ------------------------------------------------------------------------------------------------
// Sets the animation to use for playback. 
void SceneAnimator::SetAnimIndex( size_t pAnimIndex)
{
	// no change
	if( pAnimIndex == mCurrentAnimIndex)
		return;

	// kill data of the previous anim
	delete mRootNode;  mRootNode = NULL;
	delete mAnimEvaluator;  mAnimEvaluator = NULL;
	mNodesByName.clear();

	mCurrentAnimIndex = pAnimIndex;

	// create the internal node tree. Do this even in case of invalid animation index
	// so that the transformation matrices are properly set up to mimic the current scene
	mRootNode = CreateNodeTree( mScene->mRootNode, NULL);

	// invalid anim index
	if( mCurrentAnimIndex >= mScene->mNumAnimations)
		return;

	// create an evaluator for this animation
	mAnimEvaluator = new AnimEvaluator( mScene->mAnimations[mCurrentAnimIndex]);
}

// ------------------------------------------------------------------------------------------------
// Calculates the node transformations for the scene. 
void SceneAnimator::Calculate( double pTime)
{
	// invalid anim
	if( !mAnimEvaluator)
		return;

	// calculate current local transformations
	mAnimEvaluator->Evaluate( pTime);

	// and update all node transformations with the results
	UpdateTransforms( mRootNode, mAnimEvaluator->GetTransformations());
}

// ------------------------------------------------------------------------------------------------
// Retrieves the most recent local transformation matrix for the given node. 
const aiMatrix4x4& SceneAnimator::GetLocalTransform( const aiNode* node) const
{
	NodeMap::const_iterator it = mNodesByName.find( node);
	if( it == mNodesByName.end())
		return mIdentityMatrix;

	return it->second->mLocalTransform;
}

// ------------------------------------------------------------------------------------------------
// Retrieves the most recent global transformation matrix for the given node. 
const aiMatrix4x4& SceneAnimator::GetGlobalTransform( const aiNode* node) const
{
	NodeMap::const_iterator it = mNodesByName.find( node);
	if( it == mNodesByName.end())
		return mIdentityMatrix;

	return it->second->mGlobalTransform;
}

// ------------------------------------------------------------------------------------------------
// Calculates the bone matrices for the given mesh. 
const std::vector<aiMatrix4x4>& SceneAnimator::GetBoneMatrices( const aiNode* pNode, size_t pMeshIndex /* = 0 */)
{
	ai_assert( pMeshIndex < pNode->mNumMeshes);
	size_t meshIndex = pNode->mMeshes[pMeshIndex];
	ai_assert( meshIndex < mScene->mNumMeshes);
	const aiMesh* mesh = mScene->mMeshes[meshIndex];

	// resize array and initialise it with identity matrices
	mTransforms.resize( mesh->mNumBones, aiMatrix4x4());

	// calculate the mesh's inverse global transform
	aiMatrix4x4 globalInverseMeshTransform = GetGlobalTransform( pNode);
	globalInverseMeshTransform.Inverse();

	// Bone matrices transform from mesh coordinates in bind pose to mesh coordinates in skinned pose
	// Therefore the formula is offsetMatrix * currentGlobalTransform * inverseCurrentMeshTransform
	for( size_t a = 0; a < mesh->mNumBones; ++a)
	{
		const aiBone* bone = mesh->mBones[a];
		const aiMatrix4x4& currentGlobalTransform = GetGlobalTransform( mBoneNodesByName[ bone->mName.data ]);
		mTransforms[a] = globalInverseMeshTransform * currentGlobalTransform * bone->mOffsetMatrix;
	}

	// and return the result
	return mTransforms;
}

// ------------------------------------------------------------------------------------------------
// Recursively creates an internal node structure matching the current scene and animation.
SceneAnimNode* SceneAnimator::CreateNodeTree( aiNode* pNode, SceneAnimNode* pParent)
{
	// create a node
	SceneAnimNode* internalNode = new SceneAnimNode( pNode->mName.data);
	internalNode->mParent = pParent;
	mNodesByName[pNode] = internalNode;

	// copy its transformation
	internalNode->mLocalTransform = pNode->mTransformation;
	CalculateGlobalTransform( internalNode);

	// find the index of the animation track affecting this node, if any
	if( mCurrentAnimIndex < mScene->mNumAnimations)
	{
		internalNode->mChannelIndex = -1;
		const aiAnimation* currentAnim = mScene->mAnimations[mCurrentAnimIndex];
		for( unsigned int a = 0; a < currentAnim->mNumChannels; a++)
		{
			if( currentAnim->mChannels[a]->mNodeName.data == internalNode->mName)
			{
				internalNode->mChannelIndex = a;
				break;
			}
		}
	}

	// continue for all child nodes and assign the created internal nodes as our children
	for( unsigned int a = 0; a < pNode->mNumChildren; a++)
	{
		SceneAnimNode* childNode = CreateNodeTree( pNode->mChildren[a], internalNode);
		internalNode->mChildren.push_back( childNode);
	}

	return internalNode;
}

// ------------------------------------------------------------------------------------------------
// Recursively updates the internal node transformations from the given matrix array
void SceneAnimator::UpdateTransforms( SceneAnimNode* pNode, const std::vector<aiMatrix4x4>& pTransforms)
{
	// update node local transform
	if( pNode->mChannelIndex != -1)
	{
		ai_assert( pNode->mChannelIndex < pTransforms.size());
		pNode->mLocalTransform = pTransforms[pNode->mChannelIndex];
	}

	// update global transform as well
	CalculateGlobalTransform( pNode);

	// continue for all children
	for( std::vector<SceneAnimNode*>::iterator it = pNode->mChildren.begin(); it != pNode->mChildren.end(); ++it)
		UpdateTransforms( *it, pTransforms);
}

// ------------------------------------------------------------------------------------------------
// Calculates the global transformation matrix for the given internal node
void SceneAnimator::CalculateGlobalTransform( SceneAnimNode* pInternalNode)
{
	// concatenate all parent transforms to get the global transform for this node
	pInternalNode->mGlobalTransform = pInternalNode->mLocalTransform;
	SceneAnimNode* node = pInternalNode->mParent;
	while( node)
	{
		pInternalNode->mGlobalTransform = node->mLocalTransform * pInternalNode->mGlobalTransform;
		node = node->mParent;
	}
}
