crossX() Helper

Usage (2D cross)

Steps: 12*30
X(o): crossX(o, 30, 300,360, 240,60, 200,60, -240/6, Math.PI/8)
Y(o): crossY(o, 30, 300,360, 240,60, 200,60, -240/6, Math.PI/8)
Z(o): 0