sphere.java

JAVA3D矩陈的相关类

/*
 * $RCSfile: Sphere.java,v $
 *
 * Copyright (c) 2007 Sun Microsystems, Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistribution of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * - Redistribution in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in
 *   the documentation and/or other materials provided with the
 *   distribution.
 *
 * Neither the name of Sun Microsystems, Inc. or the names of
 * contributors may be used to endorse or promote products derived
 * from this software without specific prior written permission.
 *
 * This software is provided "AS IS," without a warranty of any
 * kind. ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND
 * WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY
 * EXCLUDED. SUN MICROSYSTEMS, INC. ("SUN") AND ITS LICENSORS SHALL
 * NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF
 * USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR
 * ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL,
 * CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND
 * REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF OR
 * INABILITY TO USE THIS SOFTWARE, EVEN IF SUN HAS BEEN ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGES.
 *
 * You acknowledge that this software is not designed, licensed or
 * intended for use in the design, construction, operation or
 * maintenance of any nuclear facility.
 *
 * $Revision: 1.6 $
 * $Date: 2007/04/24 18:50:59 $
 * $State: Exp $
 */

package com.sun.j3d.utils.geometry;

import com.sun.j3d.utils.geometry.*;
import java.io.*;
import java.util.*;
import javax.media.j3d.*;
import javax.vecmath.*;
import java.math.*;

/**
 * Sphere is a geometry primitive created with a given radius and resolution.
 * It is centered at the origin.
 * <p>
 * When a texture is applied to a Sphere, it is mapped CCW from the back
 * of the sphere.
 * <p>
 * By default all primitives with the same parameters share their
 * geometry (e.g., you can have 50 shperes in your scene, but the
 * geometry is stored only once). A change to one primitive will
 * effect all shared nodes.  Another implication of this
 * implementation is that the capabilities of the geometry are shared,
 * and once one of the shared nodes is live, the capabilities cannot
 * be set.  Use the GEOMETRY_NOT_SHARED flag if you do not wish to
 * share geometry among primitives with the same parameters.
 */

public class Sphere extends Primitive {

  /**
   * Sphere shape identifier, used by <code>getShape</code>.
   *
   * @see Sphere#getShape
   */
  public static final int BODY = 0;

  static final int MID_REZ_DIV = 16;
  float  radius;
  int    divisions;

  /**
   *   Constructs a Sphere of a given radius. Normals are generated
   *   by default, texture coordinates are not. The resolution defaults to  
   *   15 divisions along sphere's axes. Appearance defaults to white.
   *   @param radius Radius
   */
  public Sphere (float radius) {
    this(radius,  GENERATE_NORMALS, MID_REZ_DIV);
  }

  /**  
   *   Constructs a default Sphere of radius of 1.0. Normals are generated
   *   by default, texture coordinates are not.
   *   Resolution defaults to 15 divisions. Appearance defaults to white.
   */
  public Sphere() {
    this(1.0f, GENERATE_NORMALS, MID_REZ_DIV);
  }

  /**  
   *   Constructs a Sphere of a given radius and appearance.
   *   Normals are generated by default, texture coordinates are not.
   *   @param radius Radius
   *   @param ap Appearance
   */

  public Sphere (float radius, Appearance ap) {
    this(radius, GENERATE_NORMALS, MID_REZ_DIV, ap);
  }

  /**  
   *   Constructs a Sphere of a given radius and appearance with
   *   additional parameters specified by the Primitive flags.
   *   @param radius Radius
   *   @param primflags 
   *   @param ap appearance
   */
  public Sphere(float radius, int primflags, Appearance ap) {
    this(radius, primflags, MID_REZ_DIV, ap);
  }

  /**  
   *   Constructs a Sphere of a given radius and number of divisions
   *   with additional parameters specified by the Primitive flags.
   *   Appearance defaults to white.
   *   @param radius Radius
   *   @param divisions Divisions
   *   @param primflags Primflags
   */
  public Sphere(float radius, int primflags, int divisions) {
    this(radius, primflags, divisions, null);
  }


  /**
   * Obtains Sphere's shape node that contains the geometry.
   * This allows users to modify the appearance or geometry.
   * @param partId The part to return (must be BODY for Spheres)
   * @return The Shape3D object associated with the partId.  If an
   * invalid partId is passed in, null is returned.
   */
  public Shape3D getShape(int partId) {
    if (partId != BODY) return null;
//     return (Shape3D)((Group)getChild(0)).getChild(BODY);
    return (Shape3D)getChild(BODY);
  }

  /** Obtains Sphere's shape node that contains the geometry.
   */
  public Shape3D getShape() {
//     return (Shape3D)((Group)getChild(0)).getChild(BODY);
      return (Shape3D)getChild(BODY);
  }

  /** Sets appearance of the Sphere.
   */
  public void setAppearance(Appearance ap) {
//     ((Shape3D)((Group)getChild(0)).getChild(BODY)).setAppearance(ap);
      ((Shape3D)getChild(BODY)).setAppearance(ap);
  }

    /**
     * Gets the appearance of the specified part of the sphere.
     *
     * @param partId identifier for a given subpart of the sphere
     *
     * @return The appearance object associated with the partID.  If an
     * invalid partId is passed in, null is returned.
     *
     * @since Java 3D 1.2.1
     */
    public Appearance getAppearance(int partId) {
	if (partId != BODY) return null;
	return getShape(partId).getAppearance();
    }


  /**  
   *   Constructs a customized Sphere of a given radius, 
   *   number of divisions, and appearance, with additional parameters
   *   specified by the Primitive flags.  The resolution is defined in
   *   terms of number of subdivisions along the sphere's axes. More
   *   divisions lead to more finely tesselated objects. 
   *   <p>
   *   If the appearance is null, the sphere defaults to a white appearance.
   */
  public Sphere(float radius, int primflags, int divisions, Appearance ap) {
    super();

    int sign;
    int n, nstep;

    this.radius = radius;
    this.divisions = divisions;

    /* 
     *     The sphere algorithm evaluates spherical angles along regular
     * units. For each spherical coordinate, (theta, rho), a (x,y,z) is
     * evaluated (along with the normals and texture coordinates).
     * 
     *       The spherical angles theta varies from 0 to 2pi and rho from 0
     * to pi. Sample points depends on the number of divisions.
     */

    flags = primflags;
    boolean texCoordYUp = (flags & GENERATE_TEXTURE_COORDS_Y_UP) != 0;    
 
    //Depending on whether normal inward bit is set.
    if ((flags & GENERATE_NORMALS_INWARD) != 0) {
	sign = -1;
    } else {
	sign = 1;
    }
    
    if (divisions < 4) {
	nstep = 1;
	n = 4;
    } else {
	int mod = divisions % 4;
	if (mod == 0) {
	    n = divisions;
	} else {
	    n = divisions + (4 - mod);
	}
	nstep = n/4;
    }
    

    GeomBuffer cache = getCachedGeometry(Primitive.SPHERE,
					 radius, 0.0f, 0.0f, 
					 divisions, 0, primflags);

    Shape3D shape;

    if (cache != null) {
	shape = new Shape3D(cache.getComputedGeometry());
	numVerts += cache.getNumVerts();
	numTris += cache.getNumTris();
    } else {
	// buffer size = 8*(1 + 2E{i} + (nstep+1))
	//         where E{i} = sum of i = 2 ... nstep
	GeomBuffer gbuf = new GeomBuffer(8*nstep*(nstep+2));
	
	for (int i=0; i < 4; i++) {
	    buildQuadrant(gbuf, i*Math.PI/2, (i+1)*Math.PI/2, sign, nstep, n, true);
	    buildQuadrant(gbuf, i*Math.PI/2, (i+1)*Math.PI/2, sign, nstep, n, false);
	}

        // Fix to Issue 411. Java 3D prefers images used for texture mapping to be Y-up 
        if (texCoordYUp) {
            TexCoord2f[] texCoords  = gbuf.getTexCoords();
            if (texCoords != null) {
                for (int ii=0; ii<texCoords.length; ii++) {
                    texCoords[ii].y = 1.0f - texCoords[ii].y;
                }