vertex.java

一个用于排队系统仿真的开源软件,有非常形象的图象仿真过程!

// Copyright (C) Chris Pudney, The University of Western Australia, 1998.
// All rights reserved.
//  
// Permission to use, copy, modify and distribute this software and its
// documentation only for the purposes of teaching and research is hereby
// granted without fee, provided that the above copyright notice and this
// permission notice appear in all copies of this software/documentation
// and that you do not sell the software.  No commercial use or
// distribution of the software is permitted without the consent of the
// copyright owners.  Commercial licensing is available by contacting the
// author(s).
// 
// THIS SOFTWARE/DOCUMENTATION IS PROVIDED WITH NO WARRANTY, EXPRESS OR
// IMPLIED, INCLUDING, WITHOUT LIMITATION, WARRANTY OF MERCHANTABILITY OR
// FITNESS FOR A PARTICULAR PURPOSE.

package jmt.engine.jaba.Hull;

/**
 * A class defining a vertex.
 *
 * @author  Chris Pudney <[e-mail]>
 * @version 1.1
 */
public class Vertex
{
  /**
   * The 3D coordinates (x, y, z) of the vertex.
   */
  private int x, y, z;


  /**
   * Construct the vertex at (0, 0, 0).
   */
  public Vertex()
    {
      x = 0;
      y = 0;
      z = 0;
    }


  /**
   * Construct a vertex given a set of coordinates.
   *
   * @param x, y, z  The coordinates.
   */
  public Vertex(int x, int y, int z)
    {
      this.x = x;
      this.y = y;
      this.z = z;
    }


  /**
   * Get the coordinates of the vertex.
   *
   * @return An array of three integers containing the coordinates (x, y, z).
   */
  public int[] getCoords()
    {
      int[] c = new int[3];

      c[0] = x;
      c[1] = y;
      c[2] = z;
      return c;
    }


  /**
   * Tests whether two vertices are the same point.
   *
   * @param  v1, v2  the vertices to compare
   * @return True/false if the vertices are the same/different.
   */
  public static boolean sameVertex(Vertex v1, Vertex v2)
    {
      return v1 == v2 ||
	(v1.x == v2.x &&
	 v1.y == v2.y &&
	 v1.z == v2.z);
    }


  /**
   * Tests whether three vertices are collinear.
   *
   * @param  v1, v2, v3  the vertices to test
   * @return True/false if the vertices are collinear/non-collinear
   */
  public static boolean collinear(Vertex v1, Vertex v2, Vertex v3)
    {
      long x1 = v1.x, y1 = v1.y, z1 = v1.z;
      long x2 = v2.x, y2 = v2.y, z2 = v2.z;
      long x3 = v3.x, y3 = v3.y, z3 = v3.z;
      return (z3 - z1) * (y2 - y1) - (z2 - z1) * (y3 - y1) == 0 &&
	(z2 - z1) * (x3 - x1) - (x2 - x1) * (z3 - z1) == 0 &&
	  (x2 - x1) * (y3 - y1) - (y2 - y1) * (x3 - x1) == 0;
    }


  /**
   * Returns the pair of vertices that bound three collinear vertices.
   * 
   * @param  v1, v2, v3  the vertices to test
   * @return An array of two vertices that bound the tested vertices
   */
  public static Vertex[] bounds(Vertex v1, Vertex v2, Vertex v3)
    {
      Vertex min12, max12;

      // Compare v1 and v2    
      if (v1.x == v2.x)
	{
	  if (v1.y == v2.y)
	    {
	      if (v1.z <= v2.z)
		{
		  min12 = v1;
		  max12 = v2;
		}
	      else
		{
		  min12 = v2;
		  max12 = v1;
		}
	    }
	  else if (v1.y < v2.y)
	    {
	      min12 = v1;
	      max12 = v2;
	    }
	  else
	    {
	      min12 = v2;
	      max12 = v1;
	    }
	}
      else if (v1.x < v2.x)
	{
	  min12 = v1;
	  max12 = v2;
	}
      else
	{
	  min12 = v2;
	  max12 = v1;
	}

      Vertex[] bounds = new Vertex[2];

      // Compare min of v1, v2 with v3
      if (min12.x == v3.x)
	{
	  if (min12.y == v3.y)
	    {
	      bounds[0] = min12.z <= v3.z ? min12 : v3;
	    }
	  else
	    {
	      bounds[0] = min12.y < v3.y ? min12 : v3;
	    }
	}
      else
	{
	  bounds[0] = min12.x < v3.x ? min12 : v3;
	}


      // Compare max of v1, v2 with v3
      if (max12.x == v3.x)
	{
	  if (max12.y == v3.y)
	    {
	      bounds[1] = max12.z >= v3.z ? max12 : v3;
	    }
	  else
	    {
	      bounds[1] = max12.y > v3.y ? max12 : v3;
	    }
	}
      else
	{
	  bounds[1] = max12.x > v3.x ? max12 : v3;
	}
      return bounds;
    }

  /** 
   * Returns the square of the distance between two vertices.
   *
   * @param v1, v2  the vertices
   * @return        the distance squared between them
   */
  public static long distanceSquared(Vertex v1,
			     Vertex v2)
    {
      long x1 = v1.x, y1 = v1.y, z1 = v1.z;
      long x2 = v2.x, y2 = v2.y, z2 = v2.z;
      return (x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2) +
	(z1 - z2) * (z1 - z2);
    }

  /**
    * Returns the square of the norm of a vector
    *
    * @param v  the vector
    * @return   the square of the norm of v
    */
  public long normSq()
    {
      long x = this.x;
      long y = this.y;
      long z = this.z;
      return x * x + y * y + z * z;
    }


  /**
   * Returns the dot product of two vectors
   *
   * @param v1, v2  the vectors
   * @return        v1.v2
   */
  public static long dotProduct(Vertex v1,
			       Vertex v2)
    {
      long x1 = v1.x, y1 = v1.y, z1 = v1.z;
      long x2 = v2.x, y2 = v2.y, z2 = v2.z; 
      return x1 * x2 + y1 * y2 + z1 * z2;
    }

  /**
    * Returns the vector difference between two vertices
    *
    * @param v1, v2  the vertices
    * @return        v1 - v2
    */
  public static Vertex vectorDiff(Vertex v1,
			       Vertex v2)
    {
      return new Vertex(v1.x - v2.x,
			v1.y - v2.y,
			v1.z - v2.z);
    }

  /**
    * Returns the cross product of two vectors
    *
    * @param v1, v2  the vectors
    * @return        v1 x v2
    */
  public static Vertex crossProduct(Vertex v1,
				    Vertex v2)
    {
      return new Vertex(v1.y * v2.z - v1.z * v2.y,
			v1.z * v2.x - v1.x * v2.z,
			v1.x * v2.y - v1.y * v2.x);
    }

  /**
   * Returns a string that describes a vertex.
   */
  public String toString()
    {
      return ("(" + x + ", " + y + ", " + z + ")");
    }
}