41     u_(
p[0], 
p[1]), v_(
q[0], 
q[1])
 
   45   bool Line2D::isCrossing(Line2D& other)
 
   47     const float d = ((v_[0] - u_[0]) * (other.v_[1] - other.u_[1])
 
   48                      - (v_[1] - u_[1]) * (other.v_[0] - other.u_[0]));
 
   52     const float u = ((other.u_[0] - u_[0])*(other.v_[1] - other.u_[1])
 
   53                      - (other.u_[1] - u_[1])*(other.v_[0] - other.u_[0]))/d;
 
   54     const float v = ((other.u_[0] - u_[0])*(v_[1] - u_[1])
 
   55                      - (other.u_[1] - u_[1])*(v_[0] - u_[0]))/d;
 
   56     if (u < 0.0 || u > 1.0) {
 
   59     if (v < 0.0 || v > 1.0) {