public class LineSeg2D
{
   Vector2D p1;
   Vector2D p2;
   
   boolean killMe;
   
   LineSeg2D()
   {
     p1 = new Vector2D();
     p2 = new Vector2D();
     killMe = false;
   }
   LineSeg2D(Vector2D v1, Vector2D v2)
   {
     p1 = new Vector2D();
     p2 = new Vector2D();     
     p1.Set(v1);
     p2.Set(v2);
     killMe = false;
   }  
   LineSeg2D(float x1, float y1, float x2, float y2)
   {
     p1 = new Vector2D();
     p2 = new Vector2D();
     p1.Set(x1, y1);
     p2.Set(x2, y2);
     killMe = false;
   }
   
   public float Length()
   {
     return ((float)(p1.Minus(p2)).magnitude());
   }
   
   public Vector2D CenterPoint()
   {
     return new Vector2D((p1.x+p2.x)*.5f,(p1.y+p2.y)*.5f); 
   }
   
   public void SetP1(float x, float y)
   {
     p1.x = x;
     p1.y = y;
   }
   
   public void SetP1(Vector2D v)
   {
     p1.Set(v);
   }
   
   public void SetP2(float x, float y)
   {
     p2.x = x;
     p2.y = y;
   }
   
   public void SetP2(Vector2D v)
   {
     p2.Set(v);
   }

   public Vector2D Norm()
   {
     Vector2D v = RayVector();
     v.Rotate90CW();
     return (v);
   }

   public Vector2D UnitNorm()
   {
     Vector2D v = RayVector();
     v.Rotate90CW();
     return (v.retNormalize());
   }

   public Vector2D RayVector()
   {
     return p2.Minus(p1);
   }

   //Returns 'D' - the distance from the origin in the plane equation
   public float GetD()
   {
     return -((UnitNorm()).Dot(p1));
   }               
   
   public float LengthSquared()
   {  
      float dx = p1.x - p2.x;
      float dy = p1.y - p2.y;
      
      return (dx*dx + dy*dy);     
   }

   public LineSeg2D retReverse()
   {
     return new LineSeg2D(p2,p1);
   }
}