p1x = tx1 * cosang + ty1 * sinang + cx
p1y = -tx1 * sinang + ty1 * cosang + cy
tx2, ty2 = x2 - cx, y2 - cy
p2x = tx2 * cosang + ty2 * sinang + cx
p2y = -tx2 * sinang + ty2 * cosang + cy
pl.set_line(line, [p1x, p2x], [p1y, p2y])
Rotate line around center point given two vertices