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Open Asset Import Library (ASSIMP)
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/** @file  MakeLeftHandedProcess.cpp
 *  @brief Implementation of the post processing step to convert all
 *  imported data to a left-handed coordinate system.
 *
 *  Face order & UV flip are also implemented here, for the sake of a
 *  better location.
 */

#include "AssimpPCH.h"
#include "ConvertToLHProcess.h"

using namespace Assimp;

#ifndef ASSIMP_BUILD_NO_MAKELEFTHANDED_PROCESS

// ------------------------------------------------------------------------------------------------
// Constructor to be privately used by Importer
MakeLeftHandedProcess::MakeLeftHandedProcess()
{}

// ------------------------------------------------------------------------------------------------
// Destructor, private as well
MakeLeftHandedProcess::~MakeLeftHandedProcess()
{}

// ------------------------------------------------------------------------------------------------
// Returns whether the processing step is present in the given flag field.
bool MakeLeftHandedProcess::IsActive( unsigned int pFlags) const
{
	return 0 != (pFlags & aiProcess_MakeLeftHanded);
}

// ------------------------------------------------------------------------------------------------
// Executes the post processing step on the given imported data.
void MakeLeftHandedProcess::Execute( aiScene* pScene)
{
	// Check for an existent root node to proceed
	ai_assert(pScene->mRootNode != NULL);
	DefaultLogger::get()->debug("MakeLeftHandedProcess begin");

	// recursively convert all the nodes 
	ProcessNode( pScene->mRootNode, aiMatrix4x4());

	// process the meshes accordingly
	for( unsigned int a = 0; a < pScene->mNumMeshes; ++a)
		ProcessMesh( pScene->mMeshes[a]);

	// process the materials accordingly
	for( unsigned int a = 0; a < pScene->mNumMaterials; ++a)
		ProcessMaterial( pScene->mMaterials[a]);

	// transform all animation channels as well
	for( unsigned int a = 0; a < pScene->mNumAnimations; a++)
	{
		aiAnimation* anim = pScene->mAnimations[a];
		for( unsigned int b = 0; b < anim->mNumChannels; b++)
		{
			aiNodeAnim* nodeAnim = anim->mChannels[b];
			ProcessAnimation( nodeAnim);
		}
	}

	// flipping a single vector component means inverting face order ...
	FlipWindingOrderProcess flipper;
	flipper.Execute(pScene);

	DefaultLogger::get()->debug("MakeLeftHandedProcess finished");
}

// ------------------------------------------------------------------------------------------------
// Recursively converts a node, all of its children and all of its meshes
void MakeLeftHandedProcess::ProcessNode( aiNode* pNode, const aiMatrix4x4& pParentGlobalRotation)
{
	// mirror all base vectors at the local Z axis
	pNode->mTransformation.c1 = -pNode->mTransformation.c1;
	pNode->mTransformation.c2 = -pNode->mTransformation.c2;
	pNode->mTransformation.c3 = -pNode->mTransformation.c3;
	pNode->mTransformation.c4 = -pNode->mTransformation.c4;

	// now invert the Z axis again to keep the matrix determinant positive.
	// The local meshes will be inverted accordingly so that the result should look just fine again.
	pNode->mTransformation.a3 = -pNode->mTransformation.a3;
	pNode->mTransformation.b3 = -pNode->mTransformation.b3;
	pNode->mTransformation.c3 = -pNode->mTransformation.c3;
	pNode->mTransformation.d3 = -pNode->mTransformation.d3; // useless, but anyways...

	// continue for all children
	for( size_t a = 0; a < pNode->mNumChildren; ++a)
		ProcessNode( pNode->mChildren[a], pParentGlobalRotation * pNode->mTransformation);
}

// ------------------------------------------------------------------------------------------------
// Converts a single mesh to left handed coordinates. 
void MakeLeftHandedProcess::ProcessMesh( aiMesh* pMesh)
{
	// mirror positions, normals and stuff along the Z axis
	for( size_t a = 0; a < pMesh->mNumVertices; ++a)
	{
		pMesh->mVertices[a].z *= -1.0f;
		if( pMesh->HasNormals())
			pMesh->mNormals[a].z *= -1.0f;
		if( pMesh->HasTangentsAndBitangents())
		{
			pMesh->mTangents[a].z *= -1.0f;
			pMesh->mBitangents[a].z *= -1.0f;
		}
	}

	// mirror offset matrices of all bones
	for( size_t a = 0; a < pMesh->mNumBones; ++a)
	{
		aiBone* bone = pMesh->mBones[a];
		bone->mOffsetMatrix.a3 = -bone->mOffsetMatrix.a3;
		bone->mOffsetMatrix.b3 = -bone->mOffsetMatrix.b3;
		bone->mOffsetMatrix.d3 = -bone->mOffsetMatrix.d3;
		bone->mOffsetMatrix.c1 = -bone->mOffsetMatrix.c1;
		bone->mOffsetMatrix.c2 = -bone->mOffsetMatrix.c2;
		bone->mOffsetMatrix.c4 = -bone->mOffsetMatrix.c4;
	}

	// mirror bitangents as well as they're derived from the texture coords
	if( pMesh->HasTangentsAndBitangents())
	{
		for( unsigned int a = 0; a < pMesh->mNumVertices; a++)
			pMesh->mBitangents[a] *= -1.0f;
	}
}

// ------------------------------------------------------------------------------------------------
// Converts a single material to left handed coordinates. 
void MakeLeftHandedProcess::ProcessMaterial( aiMaterial* _mat)
{
	MaterialHelper* mat = (MaterialHelper*)_mat;
	for (unsigned int a = 0; a < mat->mNumProperties;++a)	{
		aiMaterialProperty* prop = mat->mProperties[a];

		// Mapping axis for UV mappings?
		if (!::strcmp( prop->mKey.data, "$tex.mapaxis"))	{
			ai_assert( prop->mDataLength >= sizeof(aiVector3D)); /* something is wrong with the validation if we end up here */ 
			aiVector3D* pff = (aiVector3D*)prop->mData;

			pff->z *= -1.f;
		}
	}
}

// ------------------------------------------------------------------------------------------------
// Converts the given animation to LH coordinates. 
void MakeLeftHandedProcess::ProcessAnimation( aiNodeAnim* pAnim) 
{ 
	// position keys 
	for( unsigned int a = 0; a < pAnim->mNumPositionKeys; a++) 
		pAnim->mPositionKeys[a].mValue.z *= -1.0f; 

	// rotation keys 
	for( unsigned int a = 0; a < pAnim->mNumRotationKeys; a++) 
	{ 
		/* That's the safe version, but the float errors add up. So we try the short version instead 
		aiMatrix3x3 rotmat = pAnim->mRotationKeys[a].mValue.GetMatrix(); 
		rotmat.a3 = -rotmat.a3; rotmat.b3 = -rotmat.b3; 
		rotmat.c1 = -rotmat.c1; rotmat.c2 = -rotmat.c2; 
		aiQuaternion rotquat( rotmat); 
		pAnim->mRotationKeys[a].mValue = rotquat; 
		*/ 
		pAnim->mRotationKeys[a].mValue.x *= -1.0f; 
		pAnim->mRotationKeys[a].mValue.y *= -1.0f; 
	} 
} 

#endif // !!  ASSIMP_BUILD_NO_MAKELEFTHANDED_PROCESS
#ifndef  ASSIMP_BUILD_NO_FLIPUVS_PROCESS
// # FlipUVsProcess

// ------------------------------------------------------------------------------------------------
// Constructor to be privately used by Importer
FlipUVsProcess::FlipUVsProcess()
{}

// ------------------------------------------------------------------------------------------------
// Destructor, private as well
FlipUVsProcess::~FlipUVsProcess()
{}

// ------------------------------------------------------------------------------------------------
// Returns whether the processing step is present in the given flag field.
bool FlipUVsProcess::IsActive( unsigned int pFlags) const
{
	return 0 != (pFlags & aiProcess_FlipUVs);
}

// ------------------------------------------------------------------------------------------------
// Executes the post processing step on the given imported data.
void FlipUVsProcess::Execute( aiScene* pScene)
{
	DefaultLogger::get()->debug("FlipUVsProcess begin");
	for (unsigned int i = 0; i < pScene->mNumMeshes;++i)
		ProcessMesh(pScene->mMeshes[i]);

	for (unsigned int i = 0; i < pScene->mNumMaterials;++i)
		ProcessMaterial(pScene->mMaterials[i]);
	DefaultLogger::get()->debug("FlipUVsProcess finished");
}

// ------------------------------------------------------------------------------------------------
// Converts a single material 
void FlipUVsProcess::ProcessMaterial (aiMaterial* _mat)
{
	MaterialHelper* mat = (MaterialHelper*)_mat;
	for (unsigned int a = 0; a < mat->mNumProperties;++a)	{
		aiMaterialProperty* prop = mat->mProperties[a];

		// UV transformation key?
		if (!::strcmp( prop->mKey.data, "$tex.uvtrafo"))	{
			ai_assert( prop->mDataLength >= sizeof(aiUVTransform));  /* something is wrong with the validation if we end up here */
			aiUVTransform* uv = (aiUVTransform*)prop->mData;

			// just flip it, that's everything
			uv->mTranslation.y *= -1.f;
			uv->mRotation *= -1.f;
		}
	}
}

// ------------------------------------------------------------------------------------------------
// Converts a single mesh 
void FlipUVsProcess::ProcessMesh( aiMesh* pMesh)
{
	// mirror texture y coordinate
	for( unsigned int a = 0; a < AI_MAX_NUMBER_OF_TEXTURECOORDS; a++)	{
		if( !pMesh->HasTextureCoords( a))
			break;

		for( unsigned int b = 0; b < pMesh->mNumVertices; b++)
			pMesh->mTextureCoords[a][b].y = 1.0f - pMesh->mTextureCoords[a][b].y;
	}
}

#endif // !ASSIMP_BUILD_NO_FLIPUVS_PROCESS
#ifndef  ASSIMP_BUILD_NO_FLIPWINDING_PROCESS
// # FlipWindingOrderProcess

// ------------------------------------------------------------------------------------------------
// Constructor to be privately used by Importer
FlipWindingOrderProcess::FlipWindingOrderProcess()
{}

// ------------------------------------------------------------------------------------------------
// Destructor, private as well
FlipWindingOrderProcess::~FlipWindingOrderProcess()
{}

// ------------------------------------------------------------------------------------------------
// Returns whether the processing step is present in the given flag field.
bool FlipWindingOrderProcess::IsActive( unsigned int pFlags) const
{
	return 0 != (pFlags & aiProcess_FlipWindingOrder);
}

// ------------------------------------------------------------------------------------------------
// Executes the post processing step on the given imported data.
void FlipWindingOrderProcess::Execute( aiScene* pScene)
{
	DefaultLogger::get()->debug("FlipWindingOrderProcess begin");
	for (unsigned int i = 0; i < pScene->mNumMeshes;++i)
		ProcessMesh(pScene->mMeshes[i]);
	DefaultLogger::get()->debug("FlipWindingOrderProcess finished");
}

// ------------------------------------------------------------------------------------------------
// Converts a single mesh 
void FlipWindingOrderProcess::ProcessMesh( aiMesh* pMesh)
{
	// invert the order of all faces in this mesh
	for( unsigned int a = 0; a < pMesh->mNumFaces; a++)
	{
		aiFace& face = pMesh->mFaces[a];
		for( unsigned int b = 0; b < face.mNumIndices / 2; b++)
			std::swap( face.mIndices[b], face.mIndices[ face.mNumIndices - 1 - b]);
	}
}

#endif // !! ASSIMP_BUILD_NO_FLIPWINDING_PROCESS