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diff --git a/libs/assimp/code/PostProcessing/FindDegenerates.cpp b/libs/assimp/code/PostProcessing/FindDegenerates.cpp
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+/*
+---------------------------------------------------------------------------
+Open Asset Import Library (assimp)
+---------------------------------------------------------------------------
+
+Copyright (c) 2006-2022, 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 FindDegenerates.cpp
+ * @brief Implementation of the FindDegenerates post-process step.
+*/
+
+#include "ProcessHelper.h"
+#include "FindDegenerates.h"
+
+#include <assimp/Exceptional.h>
+
+#include <unordered_map>
+
+using namespace Assimp;
+
+// Correct node indices to meshes and remove references to deleted mesh
+static void updateSceneGraph(aiNode* pNode, const std::unordered_map<unsigned int, unsigned int>& meshMap);
+
+// ------------------------------------------------------------------------------------------------
+// Constructor to be privately used by Importer
+FindDegeneratesProcess::FindDegeneratesProcess() :
+ mConfigRemoveDegenerates( false ),
+ mConfigCheckAreaOfTriangle( false ){
+ // empty
+}
+
+// ------------------------------------------------------------------------------------------------
+// Destructor, private as well
+FindDegeneratesProcess::~FindDegeneratesProcess() {
+ // nothing to do here
+}
+
+// ------------------------------------------------------------------------------------------------
+// Returns whether the processing step is present in the given flag field.
+bool FindDegeneratesProcess::IsActive( unsigned int pFlags) const {
+ return 0 != (pFlags & aiProcess_FindDegenerates);
+}
+
+// ------------------------------------------------------------------------------------------------
+// Setup import configuration
+void FindDegeneratesProcess::SetupProperties(const Importer* pImp) {
+ // Get the current value of AI_CONFIG_PP_FD_REMOVE
+ mConfigRemoveDegenerates = (0 != pImp->GetPropertyInteger(AI_CONFIG_PP_FD_REMOVE,0));
+ mConfigCheckAreaOfTriangle = ( 0 != pImp->GetPropertyInteger(AI_CONFIG_PP_FD_CHECKAREA) );
+}
+
+// ------------------------------------------------------------------------------------------------
+// Executes the post processing step on the given imported data.
+void FindDegeneratesProcess::Execute( aiScene* pScene) {
+ ASSIMP_LOG_DEBUG("FindDegeneratesProcess begin");
+ if ( nullptr == pScene) {
+ return;
+ }
+
+ std::unordered_map<unsigned int, unsigned int> meshMap;
+ meshMap.reserve(pScene->mNumMeshes);
+
+ const unsigned int originalNumMeshes = pScene->mNumMeshes;
+ unsigned int targetIndex = 0;
+ for (unsigned int i = 0; i < pScene->mNumMeshes; ++i) {
+ // Do not process point cloud, ExecuteOnMesh works only with faces data
+ if ((pScene->mMeshes[i]->mPrimitiveTypes != aiPrimitiveType::aiPrimitiveType_POINT) && ExecuteOnMesh(pScene->mMeshes[i])) {
+ delete pScene->mMeshes[i];
+ // Not strictly required, but clean:
+ pScene->mMeshes[i] = nullptr;
+ } else {
+ meshMap[i] = targetIndex;
+ pScene->mMeshes[targetIndex] = pScene->mMeshes[i];
+ ++targetIndex;
+ }
+ }
+ pScene->mNumMeshes = targetIndex;
+
+ if (meshMap.size() < originalNumMeshes) {
+ updateSceneGraph(pScene->mRootNode, meshMap);
+ }
+
+ ASSIMP_LOG_DEBUG("FindDegeneratesProcess finished");
+}
+
+static void updateSceneGraph(aiNode* pNode, const std::unordered_map<unsigned int, unsigned int>& meshMap) {
+ unsigned int targetIndex = 0;
+ for (unsigned i = 0; i < pNode->mNumMeshes; ++i) {
+ const unsigned int sourceMeshIndex = pNode->mMeshes[i];
+ auto it = meshMap.find(sourceMeshIndex);
+ if (it != meshMap.end()) {
+ pNode->mMeshes[targetIndex] = it->second;
+ ++targetIndex;
+ }
+ }
+ pNode->mNumMeshes = targetIndex;
+ //recurse to all children
+ for (unsigned i = 0; i < pNode->mNumChildren; ++i) {
+ updateSceneGraph(pNode->mChildren[i], meshMap);
+ }
+}
+
+static ai_real heron( ai_real a, ai_real b, ai_real c ) {
+ ai_real s = (a + b + c) / 2;
+ ai_real area = pow((s * ( s - a ) * ( s - b ) * ( s - c ) ), (ai_real)0.5 );
+ return area;
+}
+
+static ai_real distance3D( const aiVector3D &vA, aiVector3D &vB ) {
+ const ai_real lx = ( vB.x - vA.x );
+ const ai_real ly = ( vB.y - vA.y );
+ const ai_real lz = ( vB.z - vA.z );
+ ai_real a = lx*lx + ly*ly + lz*lz;
+ ai_real d = pow( a, (ai_real)0.5 );
+
+ return d;
+}
+
+static ai_real calculateAreaOfTriangle( const aiFace& face, aiMesh* mesh ) {
+ ai_real area = 0;
+
+ aiVector3D vA( mesh->mVertices[ face.mIndices[ 0 ] ] );
+ aiVector3D vB( mesh->mVertices[ face.mIndices[ 1 ] ] );
+ aiVector3D vC( mesh->mVertices[ face.mIndices[ 2 ] ] );
+
+ ai_real a( distance3D( vA, vB ) );
+ ai_real b( distance3D( vB, vC ) );
+ ai_real c( distance3D( vC, vA ) );
+ area = heron( a, b, c );
+
+ return area;
+}
+
+// ------------------------------------------------------------------------------------------------
+// Executes the post processing step on the given imported mesh
+bool FindDegeneratesProcess::ExecuteOnMesh( aiMesh* mesh) {
+ mesh->mPrimitiveTypes = 0;
+
+ std::vector<bool> remove_me;
+ if (mConfigRemoveDegenerates) {
+ remove_me.resize( mesh->mNumFaces, false );
+ }
+
+ unsigned int deg = 0, limit;
+ for ( unsigned int a = 0; a < mesh->mNumFaces; ++a ) {
+ aiFace& face = mesh->mFaces[a];
+ bool first = true;
+
+ // check whether the face contains degenerated entries
+ for (unsigned int i = 0; i < face.mNumIndices; ++i) {
+ // Polygons with more than 4 points are allowed to have double points, that is
+ // simulating polygons with holes just with concave polygons. However,
+ // double points may not come directly after another.
+ limit = face.mNumIndices;
+ if (face.mNumIndices > 4) {
+ limit = std::min( limit, i+2 );
+ }
+
+ for (unsigned int t = i+1; t < limit; ++t) {
+ if (mesh->mVertices[face.mIndices[ i ] ] == mesh->mVertices[ face.mIndices[ t ] ]) {
+ // we have found a matching vertex position
+ // remove the corresponding index from the array
+ --face.mNumIndices;
+ --limit;
+ for (unsigned int m = t; m < face.mNumIndices; ++m) {
+ face.mIndices[ m ] = face.mIndices[ m+1 ];
+ }
+ --t;
+
+ // NOTE: we set the removed vertex index to an unique value
+ // to make sure the developer gets notified when his
+ // application attempts to access this data.
+ face.mIndices[ face.mNumIndices ] = 0xdeadbeef;
+
+ if(first) {
+ ++deg;
+ first = false;
+ }
+
+ if ( mConfigRemoveDegenerates ) {
+ remove_me[ a ] = true;
+ goto evil_jump_outside; // hrhrhrh ... yeah, this rocks baby!
+ }
+ }
+ }
+
+ if ( mConfigCheckAreaOfTriangle ) {
+ if ( face.mNumIndices == 3 ) {
+ ai_real area = calculateAreaOfTriangle( face, mesh );
+ if (area < ai_epsilon) {
+ if ( mConfigRemoveDegenerates ) {
+ remove_me[ a ] = true;
+ ++deg;
+ goto evil_jump_outside;
+ }
+
+ // todo: check for index which is corrupt.
+ }
+ }
+ }
+ }
+
+ // We need to update the primitive flags array of the mesh.
+ switch (face.mNumIndices)
+ {
+ case 1u:
+ mesh->mPrimitiveTypes |= aiPrimitiveType_POINT;
+ break;
+ case 2u:
+ mesh->mPrimitiveTypes |= aiPrimitiveType_LINE;
+ break;
+ case 3u:
+ mesh->mPrimitiveTypes |= aiPrimitiveType_TRIANGLE;
+ break;
+ default:
+ mesh->mPrimitiveTypes |= aiPrimitiveType_POLYGON;
+ break;
+ };
+evil_jump_outside:
+ continue;
+ }
+
+ // If AI_CONFIG_PP_FD_REMOVE is true, remove degenerated faces from the import
+ if (mConfigRemoveDegenerates && deg) {
+ unsigned int n = 0;
+ for (unsigned int a = 0; a < mesh->mNumFaces; ++a)
+ {
+ aiFace& face_src = mesh->mFaces[a];
+ if (!remove_me[a]) {
+ aiFace& face_dest = mesh->mFaces[n++];
+
+ // Do a manual copy, keep the index array
+ face_dest.mNumIndices = face_src.mNumIndices;
+ face_dest.mIndices = face_src.mIndices;
+
+ if (&face_src != &face_dest) {
+ // clear source
+ face_src.mNumIndices = 0;
+ face_src.mIndices = nullptr;
+ }
+ }
+ else {
+ // Otherwise delete it if we don't need this face
+ delete[] face_src.mIndices;
+ face_src.mIndices = nullptr;
+ face_src.mNumIndices = 0;
+ }
+ }
+ // Just leave the rest of the array unreferenced, we don't care for now
+ mesh->mNumFaces = n;
+ if (!mesh->mNumFaces) {
+ //The whole mesh consists of degenerated faces
+ //signal upward, that this mesh should be deleted.
+ ASSIMP_LOG_VERBOSE_DEBUG("FindDegeneratesProcess removed a mesh full of degenerated primitives");
+ return true;
+ }
+ }
+
+ if (deg && !DefaultLogger::isNullLogger()) {
+ ASSIMP_LOG_WARN( "Found ", deg, " degenerated primitives");
+ }
+ return false;
+}
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