Changed assimp to force regeneration of normals.

code/GenFaceNormalsProcess.cpp

@@ -106,7 +106,8 @@ void GenFaceNormalsProcess::Execute( aiScene* pScene)
 bool GenFaceNormalsProcess::GenMeshFaceNormals (aiMesh* pMesh)
 {
     if (NULL != pMesh->mNormals) {
-        return false;
+        // return false;
+        delete[] pMesh->mNormals;
     }
 
     // If the mesh consists of lines and/or points but not of
@@ -135,8 +136,19 @@ bool GenFaceNormalsProcess::GenMeshFaceNormals (aiMesh* pMesh)
         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]];
+
+        auto pV12 = *pV2 - *pV1;
+        auto pV31 = *pV3 - *pV1;
+
         const aiVector3D vNor = ((*pV2 - *pV1) ^ (*pV3 - *pV1)).Normalize();
 
+        if (std::isnan(vNor.x) || std::isnan(vNor.y) || std::isnan(vNor.z)) {
+            for (unsigned int i = 0; i < face.mNumIndices; ++i) {
+                pMesh->mNormals[face.mIndices[i]] = aiVector3D(0.0f, 0.0f, 0.0f);
+            }
+            continue;
+        }
+
         for (unsigned int i = 0;i < face.mNumIndices;++i) {
             pMesh->mNormals[face.mIndices[i]] = vNor;
         }

code/GenVertexNormalsProcess.cpp

@@ -112,8 +112,10 @@ void GenVertexNormalsProcess::Execute( aiScene* pScene)
 // Executes the post processing step on the given imported data.
 bool GenVertexNormalsProcess::GenMeshVertexNormals (aiMesh* pMesh, unsigned int meshIndex)
 {
-    if (NULL != pMesh->mNormals)
-        return false;
+    if (NULL != pMesh->mNormals) {
+        delete[] pMesh->mNormals;
+    }
+//        return false;
 
     // If the mesh consists of lines and/or points but not of
     // triangles or higher-order polygons the normal vectors