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diff --git a/thirdparty/assimp/code/PostProcessing/GenVertexNormalsProcess.cpp b/thirdparty/assimp/code/PostProcessing/GenVertexNormalsProcess.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.
+---------------------------------------------------------------------------
+*/
+
+/** @file Implementation of the post processing step to generate face
+* normals for all imported faces.
+*/
+
+
+
+// internal headers
+#include "GenVertexNormalsProcess.h"
+#include "ProcessHelper.h"
+#include <assimp/Exceptional.h>
+#include <assimp/qnan.h>
+
+using namespace Assimp;
+
+// ------------------------------------------------------------------------------------------------
+// Constructor to be privately used by Importer
+GenVertexNormalsProcess::GenVertexNormalsProcess()
+: configMaxAngle( AI_DEG_TO_RAD( 175.f ) ) {
+    // empty
+}
+
+// ------------------------------------------------------------------------------------------------
+// Destructor, private as well
+GenVertexNormalsProcess::~GenVertexNormalsProcess() {
+    // nothing to do here
+}
+
+// ------------------------------------------------------------------------------------------------
+// Returns whether the processing step is present in the given flag field.
+bool GenVertexNormalsProcess::IsActive( unsigned int pFlags) const
+{
+    force_ = (pFlags & aiProcess_ForceGenNormals) != 0;
+    return (pFlags & aiProcess_GenSmoothNormals) != 0;
+}
+
+// ------------------------------------------------------------------------------------------------
+// Executes the post processing step on the given imported data.
+void GenVertexNormalsProcess::SetupProperties(const Importer* pImp)
+{
+    // Get the current value of the AI_CONFIG_PP_GSN_MAX_SMOOTHING_ANGLE property
+    configMaxAngle = pImp->GetPropertyFloat(AI_CONFIG_PP_GSN_MAX_SMOOTHING_ANGLE,(ai_real)175.0);
+    configMaxAngle = AI_DEG_TO_RAD(std::max(std::min(configMaxAngle,(ai_real)175.0),(ai_real)0.0));
+}
+
+// ------------------------------------------------------------------------------------------------
+// Executes the post processing step on the given imported data.
+void GenVertexNormalsProcess::Execute( aiScene* pScene)
+{
+    ASSIMP_LOG_DEBUG("GenVertexNormalsProcess begin");
+
+    if (pScene->mFlags & AI_SCENE_FLAGS_NON_VERBOSE_FORMAT) {
+        throw DeadlyImportError("Post-processing order mismatch: expecting pseudo-indexed (\"verbose\") vertices here");
+    }
+
+    bool bHas = false;
+    for( unsigned int a = 0; a < pScene->mNumMeshes; ++a) {
+        if(GenMeshVertexNormals( pScene->mMeshes[a],a))
+            bHas = true;
+    }
+
+    if (bHas)   {
+        ASSIMP_LOG_INFO("GenVertexNormalsProcess finished. "
+            "Vertex normals have been calculated");
+    } else {
+        ASSIMP_LOG_DEBUG("GenVertexNormalsProcess finished. "
+            "Normals are already there");
+    }
+}
+
+// ------------------------------------------------------------------------------------------------
+// Executes the post processing step on the given imported data.
+bool GenVertexNormalsProcess::GenMeshVertexNormals (aiMesh* pMesh, unsigned int meshIndex)
+{
+    if (NULL != pMesh->mNormals) {
+        if (force_) delete[] pMesh->mNormals;
+        else return false;
+    }
+
+    // If the mesh consists of lines and/or points but not of
+    // triangles or higher-order polygons the normal vectors
+    // are undefined.
+    if (!(pMesh->mPrimitiveTypes & (aiPrimitiveType_TRIANGLE | aiPrimitiveType_POLYGON)))
+    {
+        ASSIMP_LOG_INFO("Normal vectors are undefined for line and point meshes");
+        return false;
+    }
+
+    // Allocate the array to hold the output normals
+    const float qnan = std::numeric_limits<ai_real>::quiet_NaN();
+    pMesh->mNormals = new aiVector3D[pMesh->mNumVertices];
+
+    // Compute per-face normals but store them per-vertex
+    for( unsigned int a = 0; a < pMesh->mNumFaces; a++)
+    {
+        const aiFace& face = pMesh->mFaces[a];
+        if (face.mNumIndices < 3)
+        {
+            // either a point or a line -> no normal vector
+            for (unsigned int i = 0;i < face.mNumIndices;++i) {
+                pMesh->mNormals[face.mIndices[i]] = aiVector3D(qnan);
+            }
+
+            continue;
+        }
+
+        const aiVector3D* pV1 = &pMesh->mVertices[face.mIndices[0]];
+        const aiVector3D* pV2 = &pMesh->mVertices[face.mIndices[1]];
+        const aiVector3D* pV3 = &pMesh->mVertices[face.mIndices[face.mNumIndices-1]];
+        const aiVector3D vNor = ((*pV2 - *pV1) ^ (*pV3 - *pV1)).NormalizeSafe();
+
+        for (unsigned int i = 0;i < face.mNumIndices;++i) {
+            pMesh->mNormals[face.mIndices[i]] = vNor;
+        }
+    }
+
+    // Set up a SpatialSort to quickly find all vertices close to a given position
+    // check whether we can reuse the SpatialSort of a previous step.
+    SpatialSort* vertexFinder = NULL;
+    SpatialSort  _vertexFinder;
+    ai_real posEpsilon = ai_real( 1e-5 );
+    if (shared) {
+        std::vector<std::pair<SpatialSort,ai_real> >* avf;
+        shared->GetProperty(AI_SPP_SPATIAL_SORT,avf);
+        if (avf)
+        {
+            std::pair<SpatialSort,ai_real>& blubb = avf->operator [] (meshIndex);
+            vertexFinder = &blubb.first;
+            posEpsilon = blubb.second;
+        }
+    }
+    if (!vertexFinder)  {
+        _vertexFinder.Fill(pMesh->mVertices, pMesh->mNumVertices, sizeof( aiVector3D));
+        vertexFinder = &_vertexFinder;
+        posEpsilon = ComputePositionEpsilon(pMesh);
+    }
+    std::vector<unsigned int> verticesFound;
+    aiVector3D* pcNew = new aiVector3D[pMesh->mNumVertices];
+
+    if (configMaxAngle >= AI_DEG_TO_RAD( 175.f ))   {
+        // There is no angle limit. Thus all vertices with positions close
+        // to each other will receive the same vertex normal. This allows us
+        // to optimize the whole algorithm a little bit ...
+        std::vector<bool> abHad(pMesh->mNumVertices,false);
+        for (unsigned int i = 0; i < pMesh->mNumVertices;++i)   {
+            if (abHad[i]) {
+                continue;
+            }
+
+            // Get all vertices that share this one ...
+            vertexFinder->FindPositions( pMesh->mVertices[i], posEpsilon, verticesFound);
+
+            aiVector3D pcNor;
+            for (unsigned int a = 0; a < verticesFound.size(); ++a) {
+                const aiVector3D& v = pMesh->mNormals[verticesFound[a]];
+                if (is_not_qnan(v.x))pcNor += v;
+            }
+            pcNor.NormalizeSafe();
+
+            // Write the smoothed normal back to all affected normals
+            for (unsigned int a = 0; a < verticesFound.size(); ++a)
+            {
+                unsigned int vidx = verticesFound[a];
+                pcNew[vidx] = pcNor;
+                abHad[vidx] = true;
+            }
+        }
+    }
+    // Slower code path if a smooth angle is set. There are many ways to achieve
+    // the effect, this one is the most straightforward one.
+    else    {
+        const ai_real fLimit = std::cos(configMaxAngle);
+        for (unsigned int i = 0; i < pMesh->mNumVertices;++i)   {
+            // Get all vertices that share this one ...
+            vertexFinder->FindPositions( pMesh->mVertices[i] , posEpsilon, verticesFound);
+
+            aiVector3D vr = pMesh->mNormals[i];
+
+            aiVector3D pcNor;
+            for (unsigned int a = 0; a < verticesFound.size(); ++a) {
+                aiVector3D v = pMesh->mNormals[verticesFound[a]];
+
+                // Check whether the angle between the two normals is not too large.
+                // Skip the angle check on our own normal to avoid false negatives
+                // (v*v is not guaranteed to be 1.0 for all unit vectors v)
+                if (is_not_qnan(v.x) && (verticesFound[a] == i || (v * vr >= fLimit)))
+                    pcNor += v;
+            }
+            pcNew[i] = pcNor.NormalizeSafe();
+        }
+    }
+
+    delete[] pMesh->mNormals;
+    pMesh->mNormals = pcNew;
+
+    return true;
+}