- case POSITIVE_X: return directions[0];
- case NEGATIVE_X: return directions[1];
- case POSITIVE_Y: return directions[2];
- case NEGATIVE_Y: return directions[3];
- case POSITIVE_Z: return directions[4];
- case NEGATIVE_Z: return directions[5];
- default: throw invalid_argument("TextureCube::get_face_direction");
+ case POSITIVE_X: return 0;
+ case NEGATIVE_X: return 1;
+ case POSITIVE_Y: return 2;
+ case NEGATIVE_Y: return 3;
+ case POSITIVE_Z: return 4;
+ case NEGATIVE_Z: return 5;
+ default: throw invalid_argument("TextureCube::get_face_index");