closes https://github.com/assimp/assimp/issues/216: check the area of a triangle to check if its degenerated or not.

code/FBXBinaryTokenizer.cpp

@@ -422,7 +422,6 @@ bool ReadScope(TokenList& output_tokens, const char* input, const char*& cursor,
     return true;
 }
 
-
 }
 
 // ------------------------------------------------------------------------------------------------

code/FindDegenerates.cpp

@@ -56,35 +56,32 @@ using namespace Assimp;
 // ------------------------------------------------------------------------------------------------
 // Constructor to be privately used by Importer
 FindDegeneratesProcess::FindDegeneratesProcess()
-: configRemoveDegenerates (false)
-{}
+: configRemoveDegenerates (false) {
+    // empty
+}
 
 // ------------------------------------------------------------------------------------------------
 // Destructor, private as well
-FindDegeneratesProcess::~FindDegeneratesProcess()
-{
+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
-{
+bool FindDegeneratesProcess::IsActive( unsigned int pFlags) const {
     return 0 != (pFlags & aiProcess_FindDegenerates);
 }
 
 // ------------------------------------------------------------------------------------------------
 // Setup import configuration
-void FindDegeneratesProcess::SetupProperties(const Importer* pImp)
-{
+void FindDegeneratesProcess::SetupProperties(const Importer* pImp) {
     // Get the current value of AI_CONFIG_PP_FD_REMOVE
     configRemoveDegenerates = (0 != pImp->GetPropertyInteger(AI_CONFIG_PP_FD_REMOVE,0));
 }
 
 // ------------------------------------------------------------------------------------------------
 // Executes the post processing step on the given imported data.
-void FindDegeneratesProcess::Execute( aiScene* pScene)
-{
+void FindDegeneratesProcess::Execute( aiScene* pScene) {
     DefaultLogger::get()->debug("FindDegeneratesProcess begin");
     for (unsigned int i = 0; i < pScene->mNumMeshes;++i){
         ExecuteOnMesh( pScene->mMeshes[ i ] );
@@ -92,41 +89,69 @@ void FindDegeneratesProcess::Execute( aiScene* pScene)
     DefaultLogger::get()->debug("FindDegeneratesProcess finished");
 }
 
+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 ) ), 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, 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
-void FindDegeneratesProcess::ExecuteOnMesh( aiMesh* mesh)
-{
+void FindDegeneratesProcess::ExecuteOnMesh( aiMesh* mesh) {
     mesh->mPrimitiveTypes = 0;
 
     std::vector<bool> remove_me;
-    if (configRemoveDegenerates)
+    if (configRemoveDegenerates) {
         remove_me.resize( mesh->mNumFaces, false );
+    }
 
     unsigned int deg = 0, limit;
-    for (unsigned int a = 0; a < mesh->mNumFaces; ++a)
-    {
+    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)
-        {
+        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)
+            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]])
-                {
+            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.mNumIndices;
+                    --limit;
+                    for (unsigned int m = t; m < face.mNumIndices; ++m) {
                         face.mIndices[ m ] = face.mIndices[ m+1 ];
                     }
                     --t;
@@ -136,8 +161,7 @@ void FindDegeneratesProcess::ExecuteOnMesh( aiMesh* mesh)
                     // application attemps to access this data.
                     face.mIndices[ face.mNumIndices ] = 0xdeadbeef;
 
-                    if(first)
-                    {
+                    if(first) {
                         ++deg;
                         first = false;
                     }
@@ -148,6 +172,15 @@ void FindDegeneratesProcess::ExecuteOnMesh( aiMesh* mesh)
                     }
                 }
             }
+            ai_real area = calculateAreaOfTriangle( face, mesh );
+            if ( area < 1e-6 ) {
+                if ( configRemoveDegenerates ) {
+                    remove_me[ a ] = true;
+                    goto evil_jump_outside;
+                }
+
+                // todo: check for index which is corrupt.
+            }
         }
 
         // We need to update the primitive flags array of the mesh.

code/STLLoader.cpp

@@ -207,12 +207,6 @@ void STLImporter::InternReadFile( const std::string& pFile, aiScene* pScene, IOS
         throw DeadlyImportError( "Failed to determine STL storage representation for " + pFile + ".");
     }
 
-    // add all created meshes to the single node
-    /*pScene->mRootNode->mNumMeshes = pScene->mNumMeshes;
-    pScene->mRootNode->mMeshes = new unsigned int[pScene->mNumMeshes];
-    for (unsigned int i = 0; i < pScene->mNumMeshes; i++)
-        pScene->mRootNode->mMeshes[i] = i;
-    */
     // create a single default material, using a white diffuse color for consistency with
     // other geometric types (e.g., PLY).
     aiMaterial* pcMat = new aiMaterial();

code/XFileImporter.h

@@ -65,14 +65,11 @@ struct Node;
 /** The XFileImporter is a worker class capable of importing a scene from a
  * DirectX file .x
  */
-class XFileImporter : public BaseImporter
-{
+class XFileImporter : public BaseImporter {
 public:
     XFileImporter();
     ~XFileImporter();
 
-
-public:
     // -------------------------------------------------------------------
     /** Returns whether the class can handle the format of the given file.
      * See BaseImporter::CanRead() for details. */