assimp/code/PostProcessing/LimitBoneWeightsProcess.cpp

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/** Implementation of the LimitBoneWeightsProcess post processing step */


#include "LimitBoneWeightsProcess.h"
#include <assimp/SmallVector.h>
#include <assimp/StringUtils.h>
#include <assimp/postprocess.h>
#include <assimp/DefaultLogger.hpp>
#include <assimp/scene.h>
#include <stdio.h>

using namespace Assimp;

// ------------------------------------------------------------------------------------------------
// Constructor to be privately used by Importer
LimitBoneWeightsProcess::LimitBoneWeightsProcess()
{
	mMaxWeights = AI_LMW_MAX_WEIGHTS;
}

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

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

// ------------------------------------------------------------------------------------------------
// Executes the post processing step on the given imported data.
void LimitBoneWeightsProcess::Execute( aiScene* pScene)
{
	ASSIMP_LOG_DEBUG("LimitBoneWeightsProcess begin");

	for (unsigned int m = 0; m < pScene->mNumMeshes; ++m) {
		ProcessMesh(pScene->mMeshes[m]);
	}

	ASSIMP_LOG_DEBUG("LimitBoneWeightsProcess end");
}

// ------------------------------------------------------------------------------------------------
// Executes the post processing step on the given imported data.
void LimitBoneWeightsProcess::SetupProperties(const Importer* pImp)
{
	// get the current value of the property
	this->mMaxWeights = pImp->GetPropertyInteger(AI_CONFIG_PP_LBW_MAX_WEIGHTS,AI_LMW_MAX_WEIGHTS);
}

// ------------------------------------------------------------------------------------------------
// Unites identical vertices in the given mesh
void LimitBoneWeightsProcess::ProcessMesh(aiMesh* pMesh)
{
	if (!pMesh->HasBones())
		return;

	// collect all bone weights per vertex
	typedef SmallVector<Weight,8> VertexWeightArray;
	typedef std::vector<VertexWeightArray> WeightsPerVertex;
	WeightsPerVertex vertexWeights(pMesh->mNumVertices);
	size_t maxVertexWeights = 0;

	for (unsigned int b = 0; b < pMesh->mNumBones; ++b)
	{
		const aiBone* bone = pMesh->mBones[b];
		for (unsigned int w = 0; w < bone->mNumWeights; ++w)
		{
			const aiVertexWeight& vw = bone->mWeights[w];
			vertexWeights[vw.mVertexId].push_back(Weight(b, vw.mWeight));
			maxVertexWeights = std::max(maxVertexWeights, vertexWeights[vw.mVertexId].size());
		}
	}

	if (maxVertexWeights <= mMaxWeights)
		return;

	unsigned int removed = 0, old_bones = pMesh->mNumBones;

	// now cut the weight count if it exceeds the maximum
	for (WeightsPerVertex::iterator vit = vertexWeights.begin(); vit != vertexWeights.end(); ++vit)
	{
		if (vit->size() <= mMaxWeights)
			continue;

		// more than the defined maximum -> first sort by weight in descending order. That's
		// why we defined the < operator in such a weird way.
		std::sort(vit->begin(), vit->end());

		// now kill everything beyond the maximum count
		unsigned int m = static_cast<unsigned int>(vit->size());
		vit->resize(mMaxWeights);
		removed += static_cast<unsigned int>(m - vit->size());

		// and renormalize the weights
		float sum = 0.0f;
		for(const Weight* it = vit->begin(); it != vit->end(); ++it) {
			sum += it->mWeight;
		}
		if (0.0f != sum) {
			const float invSum = 1.0f / sum;
			for(Weight* it = vit->begin(); it != vit->end(); ++it) {
				it->mWeight *= invSum;
			}
		}
	}

	// clear weight count for all bone
	for (unsigned int a = 0; a < pMesh->mNumBones; ++a)
	{
		pMesh->mBones[a]->mNumWeights = 0;
	}

	// rebuild the vertex weight array for all bones
	for (unsigned int a = 0; a < vertexWeights.size(); ++a)
	{
		const VertexWeightArray& vw = vertexWeights[a];
		for (const Weight* it = vw.begin(); it != vw.end(); ++it)
		{
			aiBone* bone = pMesh->mBones[it->mBone];
			bone->mWeights[bone->mNumWeights++] = aiVertexWeight(a, it->mWeight);
		}
	}

	// remove empty bones
	unsigned int writeBone = 0;

	for (unsigned int readBone = 0; readBone< pMesh->mNumBones; ++readBone)
	{
		aiBone* bone = pMesh->mBones[readBone];
		if (bone->mNumWeights > 0)
		{
			pMesh->mBones[writeBone++] = bone;
		}
		else
		{
			delete bone;
		}
	}
	pMesh->mNumBones = writeBone;

	if (!DefaultLogger::isNullLogger()) {
		ASSIMP_LOG_INFO_F("Removed ", removed, " weights. Input bones: ", old_bones, ". Output bones: ", pMesh->mNumBones);
	}
}