// add the rotation
rm[axis1][axis1] = +Math.cos(angle);
rm[axis1][axis2] = -Math.sin(angle);
rm[axis2][axis1] = +Math.sin(angle);
rm[axis2][axis2] = +Math.cos(angle);
t.addMatrix(new Matrix(rm));
Matrix tm2 = t.getTransformation();
// We know that we didn't do any translations and tm is the unity matrix
// so we can manually do the rotation on it, too.
tm.set(axis1, axis1, +Math.cos(angle));