点线面关系

射线与射线的交点计算

p0,v0
p1,v1
if v1.x * v0.y == v0.x * v1.y
  # 两条射线平行 无交点
else
  t0 = ((p0.x - p1.x) * v1.y - (p0.y - p1.y) * v1.x) / (v1.x * v0.y - v0.x * v1.y)
  t1 = ((p0.x - p1.x) * v0.y - (p0.y - p1.y) * v0.x) / (v1.x * v0.y - v0.x * v1.y)
  if t0 <= Fix16(0) or t1 <= Fix16(0)
    # 交点不在两射线方向，不相交
  else
    p = p0.x + v0.x * t0 , p0.y + v0.y * t0