geometry.java

j3me java

/*
 * J3DME Fast 3D software rendering for small devices
 * Copyright (C) 2001 Onno Hommes
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOS.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

package net.jscience.j3dme;

/**
 * This class is the root of all geometry types. It enforces that each
 * geometry is based on an array of int's known as the coordinate stream.
 * The coordinate stream is either empty or contains a a stream of int's
 * representing the x,y and z component of a vertex or normal vector.
 * The x,y and z components are all normal ints and should not contain
 * fixed point integers.
 *
 * @see Wireframe
 */
abstract class Geometry{

  protected int[] x;
  protected int[] y;
  protected int[] z;
  protected int bounding_radius;

  /**
   * Return the bounding radius of a geometry<p>
   * This method returns the bounding radius. The bounding radius defines
   * a sphere that encapsulates the 3D object defined by the geometry
   * object. This sphere is used to determine if a 3D-object is in the
   * view frustrum (in the field of view of a camera). This concept is
   * similar to the bounding box principle. However the bounding sphere
   * is a simpler version that does not require much machine cycles.
   *
   * @return The radius of the bounding sphere.
   */
  public int getBoundingRadius(){
    return bounding_radius;
  }

  /*
   * This method cheats it just takes the largest coordinate component.
   */
  protected int setBoundingRadius(){
     int radius = -1;
     for(int i=0;i<x.length;i++){
        radius = Math.max(radius,Math.abs(x[i]));
        radius = Math.max(radius,Math.abs(y[i]));
        radius = Math.max(radius,Math.abs(z[i]));
     }
     return radius;
  }
}