assimp/code/JoinVerticesProcess.cpp

/*
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Open Asset Import Library (ASSIMP)
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*/

/** @file Implementation of the post processing step to join identical vertices
 * for all imported meshes
 */

#include "AssimpPCH.h"

// internal headers
#include "JoinVerticesProcess.h"
#include "ProcessHelper.h"

using namespace Assimp;

// Data structure to keep a vertex in an interlaced format
struct Vertex
{
	aiVector3D mPosition;
	aiVector3D mNormal;
	aiVector3D mTangent, mBitangent;
	aiColor4D  mColors     [AI_MAX_NUMBER_OF_COLOR_SETS];
	aiVector3D mTexCoords  [AI_MAX_NUMBER_OF_TEXTURECOORDS];
};

// ------------------------------------------------------------------------------------------------
// Constructor to be privately used by Importer
JoinVerticesProcess::JoinVerticesProcess()
{
	// nothing to do here
}

// ------------------------------------------------------------------------------------------------
// Destructor, private as well
JoinVerticesProcess::~JoinVerticesProcess()
{
	// nothing to do here
}

// ------------------------------------------------------------------------------------------------
// Returns whether the processing step is present in the given flag field.
bool JoinVerticesProcess::IsActive( unsigned int pFlags) const
{
	return (pFlags & aiProcess_JoinIdenticalVertices) != 0;
}
// ------------------------------------------------------------------------------------------------
// Executes the post processing step on the given imported data.
void JoinVerticesProcess::Execute( aiScene* pScene)
{
	DefaultLogger::get()->debug("JoinVerticesProcess begin");

	// get the total number of vertices BEFORE the step is executed
	int iNumOldVertices = 0;
	if (!DefaultLogger::isNullLogger()) {
		for( unsigned int a = 0; a < pScene->mNumMeshes; a++)	{
			iNumOldVertices +=	pScene->mMeshes[a]->mNumVertices;
		}
	}

	// execute the step
	int iNumVertices = 0;
	for( unsigned int a = 0; a < pScene->mNumMeshes; a++)	{
		iNumVertices +=	ProcessMesh( pScene->mMeshes[a],a);
	}

	// if logging is active, print detailed statistics
	if (!DefaultLogger::isNullLogger())
	{
		if (iNumOldVertices == iNumVertices)DefaultLogger::get()->debug("JoinVerticesProcess finished ");
		else
		{
			char szBuff[128]; // should be sufficiently large in every case
			sprintf(szBuff,"JoinVerticesProcess finished | Verts in: %i out: %i | ~%.1f%%",
				iNumOldVertices,
				iNumVertices,
				((iNumOldVertices - iNumVertices) / (float)iNumOldVertices) * 100.f);
			DefaultLogger::get()->info(szBuff);
		}
	}

	pScene->mFlags |= AI_SCENE_FLAGS_NON_VERBOSE_FORMAT;
}

// ------------------------------------------------------------------------------------------------
// Unites identical vertices in the given mesh
int JoinVerticesProcess::ProcessMesh( aiMesh* pMesh, unsigned int meshIndex)
{
	BOOST_STATIC_ASSERT( AI_MAX_NUMBER_OF_COLOR_SETS    == 4);
	BOOST_STATIC_ASSERT( AI_MAX_NUMBER_OF_TEXTURECOORDS == 4);

	// Return early if we don't have any positions
	if (!pMesh->HasPositions() || !pMesh->HasFaces())
		return 0;

	// We'll never have more vertices afterwards.
	std::vector<Vertex> uniqueVertices;
	uniqueVertices.reserve( pMesh->mNumVertices);

	// For each vertex the index of the vertex it was replaced by. 
	std::vector<unsigned int> replaceIndex( pMesh->mNumVertices, 0xffffffff);
	// for each vertex whether it was replaced by an existing unique vertex (true) or a new vertex was created for it (false)
	std::vector<bool> isVertexUnique( pMesh->mNumVertices, false);

	// A little helper to find locally close vertices faster
	// FIX: check whether we can reuse the SpatialSort of a previous step
	const static float epsilon = 1e-5f;
	float posEpsilonSqr;
	SpatialSort*  vertexFinder = NULL;
	SpatialSort  _vertexFinder;
	if (shared)	{
		std::vector<std::pair<SpatialSort,float> >* avf;
		shared->GetProperty(AI_SPP_SPATIAL_SORT,avf);
		if (avf)	{
			std::pair<SpatialSort,float>& blubb = avf->operator [] (meshIndex);
			vertexFinder  = &blubb.first;posEpsilonSqr = blubb.second;
		}
	}
	if (!vertexFinder)	{
		_vertexFinder.Fill(pMesh->mVertices, pMesh->mNumVertices, sizeof( aiVector3D));
		vertexFinder = &_vertexFinder; 
		posEpsilonSqr = ComputePositionEpsilon(pMesh);
	}

	// squared because we check against squared length of the vector difference
	static const float squareEpsilon = epsilon * epsilon;

	// again, better waste some bytes than a realloc ...
	std::vector<unsigned int> verticesFound;
	verticesFound.reserve(10);

	// run an optimized code path if we don't have multiple UVs or vertex colors
	const bool complex = (
		pMesh->mTextureCoords[1]	||
		pMesh->mTextureCoords[2]	|| 
		pMesh->mTextureCoords[3]	||
		pMesh->mColors[0]			|| 
		pMesh->mColors[1]			|| 
		pMesh->mColors[2]			||
		pMesh->mColors[3] );

	// Now check each vertex if it brings something new to the table
	for( unsigned int a = 0; a < pMesh->mNumVertices; a++)
	{
		// collect the vertex data
		Vertex v;
		v.mPosition = pMesh->mVertices[a];

		if (pMesh->mNormals)
			v.mNormal = pMesh->mNormals[a];
		if (pMesh->mTangents)
			v.mTangent = pMesh->mTangents[a];
		if (pMesh->mBitangents)
			v.mBitangent = pMesh->mBitangents[a];

		if (pMesh->mColors[0]) { // manually unrolled here
			v.mColors[0] = pMesh->mColors[0][a];
			if (pMesh->mColors[1]) {
				v.mColors[1] = pMesh->mColors[1][a];
				if (pMesh->mColors[2]) {
					v.mColors[2] = pMesh->mColors[2][a];
					if (pMesh->mColors[3]) {
						v.mColors[3] = pMesh->mColors[3][a];
		}}}}
		if (pMesh->mTextureCoords[0]) { // manually unrolled here
			v.mTexCoords[0] = pMesh->mTextureCoords[0][a];
			if (pMesh->mTextureCoords[1]) {
				v.mTexCoords[1] = pMesh->mTextureCoords[1][a];
				if (pMesh->mTextureCoords[2]) {
					v.mTexCoords[2] = pMesh->mTextureCoords[2][a];
					if (pMesh->mTextureCoords[3]) {
						v.mTexCoords[3] = pMesh->mTextureCoords[3][a];
		}}}}

		// collect all vertices that are close enough to the given position
		vertexFinder->FindPositions( v.mPosition, posEpsilonSqr, verticesFound);

		unsigned int matchIndex = 0xffffffff;
		// check all unique vertices close to the position if this vertex is already present among them
		for( unsigned int b = 0; b < verticesFound.size(); b++)
		{
			const unsigned int vidx = verticesFound[b];
			const unsigned int uidx = replaceIndex[ vidx];
			if( uidx == 0xffffffff || !isVertexUnique[ vidx])
				continue;

			const Vertex& uv = uniqueVertices[ uidx];
			// Position mismatch is impossible - the vertex finder already discarded all non-matching positions

			// We just test the other attributes even if they're not present in the mesh.
			// In this case they're initialized to 0 so the comparision succeeds. 
			// By this method the non-present attributes are effectively ignored in the comparision.
			if( (uv.mNormal - v.mNormal).SquareLength() > squareEpsilon)
				continue;
			if( (uv.mTangent - v.mTangent).SquareLength() > squareEpsilon)
				continue;
			if( (uv.mBitangent - v.mBitangent).SquareLength() > squareEpsilon)
				continue;

			if( (uv.mTexCoords[0] - v.mTexCoords[0]).SquareLength() > squareEpsilon)
				continue;

			// Usually we won't have vertex colors or multiple UVs, so we can skip from here
			// Actually this increases runtime performance slightly.
			if (complex) 
			{
				// manually unrolled because continue wouldn't work as desired in an inner loop
				if( GetColorDifference( uv.mColors[0], v.mColors[0]) > squareEpsilon)
					continue;
				if( GetColorDifference( uv.mColors[1], v.mColors[1]) > squareEpsilon)
					continue;
				if( GetColorDifference( uv.mColors[2], v.mColors[2]) > squareEpsilon)
					continue;
				if( GetColorDifference( uv.mColors[3], v.mColors[3]) > squareEpsilon)
					continue;

				// texture coord matching manually unrolled as well
				if( (uv.mTexCoords[1] - v.mTexCoords[1]).SquareLength() > squareEpsilon)
					continue;
				if( (uv.mTexCoords[2] - v.mTexCoords[2]).SquareLength() > squareEpsilon)
					continue;
				if( (uv.mTexCoords[3] - v.mTexCoords[3]).SquareLength() > squareEpsilon)
					continue;
			}

			// we're still here -> this vertex perfectly matches our given vertex
			matchIndex = uidx;
			break;
		}

		// found a replacement vertex among the uniques?
		if( matchIndex != 0xffffffff)
		{
			// store where to found the matching unique vertex
			replaceIndex[a] = matchIndex;
			isVertexUnique[a] = false;
		}
		else
		{
			// no unique vertex matches it upto now -> so add it
			replaceIndex[a] = (unsigned int)uniqueVertices.size();
			uniqueVertices.push_back( v);
			isVertexUnique[a] = true;
		}
	}

	if (!DefaultLogger::isNullLogger() && DefaultLogger::get()->getLogSeverity() == Logger::VERBOSE)
	{
		char szBuff[128]; // should be sufficiently large in every case
		::sprintf(szBuff,"Mesh %i | Verts in: %i out: %i | ~%.1f%%",
			meshIndex,
			pMesh->mNumVertices,
			(int)uniqueVertices.size(),
			((pMesh->mNumVertices - uniqueVertices.size()) / (float)pMesh->mNumVertices) * 100.f);
		DefaultLogger::get()->debug(szBuff);
	}

	// replace vertex data with the unique data sets
	pMesh->mNumVertices = (unsigned int)uniqueVertices.size();

	// Position
	delete [] pMesh->mVertices;
	pMesh->mVertices = new aiVector3D[pMesh->mNumVertices];
	for( unsigned int a = 0; a < pMesh->mNumVertices; a++)
		pMesh->mVertices[a] = uniqueVertices[a].mPosition;

	// Normals, if present
	if( pMesh->mNormals)
	{
		delete [] pMesh->mNormals;
		pMesh->mNormals = new aiVector3D[pMesh->mNumVertices];
		for( unsigned int a = 0; a < pMesh->mNumVertices; a++)
			pMesh->mNormals[a] = uniqueVertices[a].mNormal;
	}
	// Tangents, if present
	if( pMesh->mTangents)
	{
		delete [] pMesh->mTangents;
		pMesh->mTangents = new aiVector3D[pMesh->mNumVertices];
		for( unsigned int a = 0; a < pMesh->mNumVertices; a++)
			pMesh->mTangents[a] = uniqueVertices[a].mTangent;
	}
	// Bitangents as well
	if( pMesh->mBitangents)
	{
		delete [] pMesh->mBitangents;
		pMesh->mBitangents = new aiVector3D[pMesh->mNumVertices];
		for( unsigned int a = 0; a < pMesh->mNumVertices; a++)
			pMesh->mBitangents[a] = uniqueVertices[a].mBitangent;
	}
	// Vertex colors
	for( unsigned int a = 0; a < AI_MAX_NUMBER_OF_COLOR_SETS; a++)
	{
		if( !pMesh->mColors[a])
			break;

		delete [] pMesh->mColors[a];
		pMesh->mColors[a] = new aiColor4D[pMesh->mNumVertices];
		for( unsigned int b = 0; b < pMesh->mNumVertices; b++)
			pMesh->mColors[a][b] = uniqueVertices[b].mColors[a];
	}
	// Texture coords
	for( unsigned int a = 0; a < AI_MAX_NUMBER_OF_TEXTURECOORDS; a++)
	{
		if( !pMesh->mTextureCoords[a])
			break;

		delete [] pMesh->mTextureCoords[a];
		pMesh->mTextureCoords[a] = new aiVector3D[pMesh->mNumVertices];
		for( unsigned int b = 0; b < pMesh->mNumVertices; b++)
			pMesh->mTextureCoords[a][b] = uniqueVertices[b].mTexCoords[a];
	}

	// adjust the indices in all faces
	for( unsigned int a = 0; a < pMesh->mNumFaces; a++)
	{
		aiFace& face = pMesh->mFaces[a];
		for( unsigned int b = 0; b < face.mNumIndices; b++)	{
			face.mIndices[b] = replaceIndex[face.mIndices[b]];
		}
	}

	// adjust bone vertex weights.
	for( int a = 0; a < (int)pMesh->mNumBones; a++)
	{
		aiBone* bone = pMesh->mBones[a];
		std::vector<aiVertexWeight> newWeights;
		newWeights.reserve( bone->mNumWeights);

		for( unsigned int b = 0; b < bone->mNumWeights; b++)
		{
			const aiVertexWeight& ow = bone->mWeights[b];
			// if the vertex is a unique one, translate it
			if( isVertexUnique[ow.mVertexId])
			{
				aiVertexWeight nw;
				nw.mVertexId = replaceIndex[ow.mVertexId];
				nw.mWeight = ow.mWeight;
				newWeights.push_back( nw);
			}
		}

		if (newWeights.size() > 0) {
			// kill the old and replace them with the translated weights
			delete [] bone->mWeights;
			bone->mNumWeights = (unsigned int)newWeights.size();

			bone->mWeights = new aiVertexWeight[bone->mNumWeights];
			memcpy( bone->mWeights, &newWeights[0], bone->mNumWeights * sizeof( aiVertexWeight));
		}
		else {
		
			/*  NOTE:
			 *
			 *  In the algorithm above we're assuming that there are no vertices
			 *  with a different bone weight setup at the same position. That wouldn't
			 *  make sense, but it is not absolutely impossible. SkeletonMeshBuilder
			 *  for example generates such input data if two skeleton points
			 *  share the same position. Again this doesn't make sense but is
			 *  reality for some model formats (MD5 for example uses these special
			 *  nodes as attachment tags for its weapons). 
			 *
			 *  Then it is possible that a bone has no weights anymore .... as a quick
			 *  workaround, we're just removing these bones. If they're animated,
			 *  model geometry might be modified but at least there's no risk of a crash.
			 */
			delete bone;
			--pMesh->mNumBones;
			for (unsigned int n = a; n < pMesh->mNumBones; ++n) 
				pMesh->mBones[n] = pMesh->mBones[n+1];

			--a; 
			DefaultLogger::get()->warn("Removing bone -> no weights remaining");
		}
	}
	return pMesh->mNumVertices;
}