Transposes just the upper 3x3 rotation matrix.
Source
void transposeRotation() {
double temp;
temp = _m4storage[1];
_m4storage[1] = _m4storage[4];
_m4storage[4] = temp;
temp = _m4storage[2];
_m4storage[2] = _m4storage[8];
_m4storage[8] = temp;
temp = _m4storage[4];
_m4storage[4] = _m4storage[1];
_m4storage[1] = temp;
temp = _m4storage[6];
_m4storage[6] = _m4storage[9];
_m4storage[9] = temp;
temp = _m4storage[8];
_m4storage[8] = _m4storage[2];
_m4storage[2] = temp;
temp = _m4storage[9];
_m4storage[9] = _m4storage[6];
_m4storage[6] = temp;
}