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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() = default;

// ------------------------------------------------------------------------------------------------
// 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];

 if (vertexWeights.size() <= vw.mVertexId)
 continue;

 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("Removed ", removed, " weights. Input bones: ", old_bones, ". Output bones: ", pMesh->mNumBones);
 }
}