prevent glm assertion failing when normalizing normals in loadGeometryDataFromOBJ

src/ACGL/OpenGL/Data/GeometryDataLoadStoreOBJ.cc

@@ -307,7 +307,9 @@ SharedGeometryData loadGeometryDataFromOBJ(const std::string& _filename, bool _c
                 glm::vec3 v0 = (glm::vec3)positionData[indices[3 * triangleIndex + 0].position];
                 glm::vec3 v1 = (glm::vec3)positionData[indices[3 * triangleIndex + 1].position];
                 glm::vec3 v2 = (glm::vec3)positionData[indices[3 * triangleIndex + 2].position];
-                glm::vec3 normal = glm::normalize(glm::cross(v1 - v0, v2 - v0));
+                glm::vec3 normal = glm::cross(v1 - v0, v2 - v0);
+                if (normal != glm::vec3(0))
+                    normal = glm::normalize(normal);
                 abData[pos++] = normal.x;
                 abData[pos++] = normal.y;
                 abData[pos++] = normal.z;