3d rotation fast

function turn (X, Y) {
	// for the math, see http://www.texpaste.com/n/ev3443eo
        var
            X2 = X*X, Y2 = Y*Y,
            q = 1 + X2 + Y2,
            s = 1 - X2 - Y2,
            r2 = 1/(q*q), s2 = s*s,
            A = (s2 + 4*(Y2 - X2))*r2, B = -8*X*Y*r2, C = 4*s*X*r2,
                D = (s2 + 4*(X2 - Y2))*r2, E = 4*s*Y*r2,
                    F = (s2 - 4*(X2 + Y2))*r2;
        mat4.multiply(mo_matrix, [
                     A,  B, C, 0,
                     B,  D, E, 0,
                    -C, -E, F, 0,
                     0,  0, 0, 1
                    ],
                mo_matrix);
    }