Reverted bitangent calculation to ASSIMP's good old code in model.cpp

auto_vk_toolkit/src/model.cpp

@@ -1489,17 +1489,17 @@ namespace avk
 		    tangent.x = (w.x * sy - v.x * ty) * dirCorrection;
 		    tangent.y = (w.y * sy - v.y * ty) * dirCorrection;
 		    tangent.z = (w.z * sy - v.z * ty) * dirCorrection;
-		    bitangent.x = (- w.x * sx + v.x * tx) * dirCorrection;
-		    bitangent.y = (- w.y * sx + v.y * tx) * dirCorrection;
-		    bitangent.z = (- w.z * sx + v.z * tx) * dirCorrection;
+		    bitangent.x = (w.x * sx - v.x * tx) * dirCorrection;
+		    bitangent.y = (w.y * sx - v.y * tx) * dirCorrection;
+		    bitangent.z = (w.z * sx - v.z * tx) * dirCorrection;
 
 		    // store for every vertex of that face
 		    for (unsigned int b = 0; b < face.mNumIndices; ++b) {
 		        unsigned int p = face.mIndices[b];
 
 		        // project tangent and bitangent into the plane formed by the vertex' normal
 		        aiVector3D localTangent = tangent - meshNorm[p] * (tangent * meshNorm[p]);
-		        aiVector3D localBitangent = bitangent - meshNorm[p] * (bitangent * meshNorm[p]) - localTangent * (bitangent * localTangent);
+		        aiVector3D localBitangent = bitangent - meshNorm[p] * (bitangent * meshNorm[p]);
 		        localTangent.NormalizeSafe();
 		        localBitangent.NormalizeSafe();