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diff --git a/thirdparty/assimp/code/LimitBoneWeightsProcess.cpp b/thirdparty/assimp/code/LimitBoneWeightsProcess.cpp
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+++ b/thirdparty/assimp/code/LimitBoneWeightsProcess.cpp
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+/*
+Open Asset Import Library (assimp)
+----------------------------------------------------------------------
+
+Copyright (c) 2006-2019, assimp 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 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.
+
+----------------------------------------------------------------------
+*/
+
+/** Implementation of the LimitBoneWeightsProcess post processing step */
+
+
+#include "LimitBoneWeightsProcess.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 a = 0; a < pScene->mNumMeshes; ++a ) {
+        ProcessMesh(pScene->mMeshes[a]);
+    }
+
+    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 std::vector< std::vector< Weight > > WeightsPerVertex;
+    WeightsPerVertex vertexWeights( pMesh->mNumVertices);
+
+    // collect all weights per vertex
+    for( unsigned int a = 0; a < pMesh->mNumBones; a++)
+    {
+        const aiBone* bone = pMesh->mBones[a];
+        for( unsigned int b = 0; b < bone->mNumWeights; b++)
+        {
+            const aiVertexWeight& w = bone->mWeights[b];
+            vertexWeights[w.mVertexId].push_back( Weight( a, w.mWeight));
+        }
+    }
+
+    unsigned int removed = 0, old_bones = pMesh->mNumBones;
+
+    // now cut the weight count if it exceeds the maximum
+    bool bChanged = false;
+    for( WeightsPerVertex::iterator vit = vertexWeights.begin(); vit != vertexWeights.end(); ++vit)
+    {
+        if( vit->size() <= mMaxWeights)
+            continue;
+
+        bChanged = true;
+
+        // 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->erase( vit->begin() + mMaxWeights, vit->end());
+        removed += static_cast<unsigned int>(m-vit->size());
+
+        // and renormalize the weights
+        float sum = 0.0f;
+        for( std::vector<Weight>::const_iterator it = vit->begin(); it != vit->end(); ++it ) {
+            sum += it->mWeight;
+        }
+        if( 0.0f != sum ) {
+            const float invSum = 1.0f / sum;
+            for( std::vector<Weight>::iterator it = vit->begin(); it != vit->end(); ++it ) {
+                it->mWeight *= invSum;
+            }
+        }
+    }
+
+    if (bChanged)   {
+        // rebuild the vertex weight array for all bones
+        typedef std::vector< std::vector< aiVertexWeight > > WeightsPerBone;
+        WeightsPerBone boneWeights( pMesh->mNumBones);
+        for( unsigned int a = 0; a < vertexWeights.size(); a++)
+        {
+            const std::vector<Weight>& vw = vertexWeights[a];
+            for( std::vector<Weight>::const_iterator it = vw.begin(); it != vw.end(); ++it)
+                boneWeights[it->mBone].push_back( aiVertexWeight( a, it->mWeight));
+        }
+
+        // and finally copy the vertex weight list over to the mesh's bones
+        std::vector<bool> abNoNeed(pMesh->mNumBones,false);
+        bChanged = false;
+
+        for( unsigned int a = 0; a < pMesh->mNumBones; a++)
+        {
+            const std::vector<aiVertexWeight>& bw = boneWeights[a];
+            aiBone* bone = pMesh->mBones[a];
+
+            if ( bw.empty() )
+            {
+                abNoNeed[a] = bChanged = true;
+                continue;
+            }
+
+            // copy the weight list. should always be less weights than before, so we don't need a new allocation
+            ai_assert( bw.size() <= bone->mNumWeights);
+            bone->mNumWeights = static_cast<unsigned int>( bw.size() );
+            ::memcpy( bone->mWeights, &bw[0], bw.size() * sizeof( aiVertexWeight));
+        }
+
+        if (bChanged)   {
+            // the number of new bones is smaller than before, so we can reuse the old array
+            aiBone** ppcCur = pMesh->mBones;aiBone** ppcSrc = ppcCur;
+
+            for (std::vector<bool>::const_iterator iter  = abNoNeed.begin();iter != abNoNeed.end()  ;++iter)    {
+                if (*iter)  {
+                    delete *ppcSrc;
+                    --pMesh->mNumBones;
+                }
+                else *ppcCur++ = *ppcSrc;
+                ++ppcSrc;
+            }
+        }
+
+        if (!DefaultLogger::isNullLogger()) {
+            ASSIMP_LOG_INFO_F("Removed ", removed, " weights. Input bones: ", old_bones, ". Output bones: ", pMesh->mNumBones );
+        }
+    }
+}