basisGradient[0] = 4.0 * rr + 4.0 * ss - 3.0;
basisGradient[1] = 4.0 * rr + 4.0 * ss - 3.0;
basisGradient[2] = 0.0;

basisGradient[3] = 4.0 * rr - 1.0;
basisGradient[4] = 0.0;
basisGradient[5] = 0.0;

basisGradient[6] = 0.0;
basisGradient[7] = 4.0 * ss - 1.0;
basisGradient[8] = 0.0;

basisGradient[9] = -4.0 * (2.0 * rr + ss - 1.0);
basisGradient[10] = -4.0 * rr;
basisGradient[11] = 0.0;

basisGradient[12] = 4.0 * ss;
basisGradient[13] = 4.0 * rr;
basisGradient[14] = 0.0;

basisGradient[15] = -4.0 * ss;
basisGradient[16] = -4.0 * (rr + 2.0 * ss - 1.0);
basisGradient[17] = 0.0;
