project.java

JAVA3D矩陈的相关类

/*
 * $RCSfile: Project.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: 1.4 $
 * $Date: 2007/02/09 17:20:20 $
 * $State: Exp $
 */

// ----------------------------------------------------------------------
//
// The reference to Fast Industrial Strength Triangulation (FIST) code
// in this release by Sun Microsystems is related to Sun's rewrite of
// an early version of FIST. FIST was originally created by Martin
// Held and Joseph Mitchell at Stony Brook University and is
// incorporated by Sun under an agreement with The Research Foundation
// of SUNY (RFSUNY). The current version of FIST is available for
// commercial use under a license agreement with RFSUNY on behalf of
// the authors and Stony Brook University.  Please contact the Office
// of Technology Licensing at Stony Brook, phone [phone], for
// licensing information.
//
// ----------------------------------------------------------------------

package com.sun.j3d.utils.geometry;

import javax.vecmath.*;
import java.io.*;
import java.util.*;

class Project  {

    /**
     * This function projects the vertices of the polygons referenced by
     * loops[i1,..,i2-1] to an approximating plane.
     */
    static void projectFace(Triangulator triRef, int loopMin, int loopMax) {
	Vector3f	 normal, nr;
	int i, j;
	double d;

	normal = new Vector3f();
	nr = new Vector3f();

	// determine the normal of the plane onto which the points get projected
	determineNormal(triRef, triRef.loops[loopMin], normal);
	j = loopMin + 1;
	if (j < loopMax) {
	    for (i = j;  i < loopMax;  ++i) {
		determineNormal(triRef, triRef.loops[i], nr);
		if (Basic.dotProduct(normal, nr) < 0.0) {
		    Basic.invertVector(nr);
		}
		Basic.vectorAdd(normal, nr, normal);
	    }
	    d = Basic.lengthL2(normal);
	    if (Numerics.gt(d, Triangulator.ZERO)) {
		Basic.divScalar(d, normal);
	    }
	    else {
		// System.out.println("*** ProjectFace: zero-length normal vector!? ***\n");
		normal.x = normal.y = 0.0f;
		normal.z = 1.0f;
	    }
	}

	// project the points onto this plane. the projected points are stored in
	// the array `points[0,..,numPoints]'

	// System.out.println("loopMin " + loopMin + " loopMax " + loopMax);
	projectPoints(triRef, loopMin, loopMax, normal);

    }


    /**
     * This function computes the average of all normals defined by triples of
     * successive vertices of the polygon. we'll see whether this is a good
     * heuristic for finding a suitable plane normal...
     */
    static void determineNormal(Triangulator triRef, int ind, Vector3f normal) {
	Vector3f nr, pq, pr;
	int ind0, ind1, ind2;
	int i0, i1, i2;
	double d;

	ind1 = ind;
	i1 = triRef.fetchData(ind1);
	ind0 = triRef.fetchPrevData(ind1);
	i0 = triRef.fetchData(ind0);
	ind2 = triRef.fetchNextData(ind1);
	i2 = triRef.fetchData(ind2);
	pq = new Vector3f();
	Basic.vectorSub((Tuple3f) triRef.vertices[i0], (Tuple3f) triRef.vertices[i1], (Vector3f) pq);
	pr = new Vector3f();
	Basic.vectorSub((Tuple3f) triRef.vertices[i2], (Tuple3f) triRef.vertices[i1], (Vector3f) pr);
	nr = new Vector3f();
	Basic.vectorProduct(pq, pr, nr);
	d = Basic.lengthL2(nr);
	if (Numerics.gt(d, Triangulator.ZERO)) {
	    Basic.divScalar(d, nr);
	    normal.set(nr);
	}
	else {
	    normal.x = normal.y = normal.z = 0.0f;
	}

	pq.set(pr);
	ind1 = ind2;
	ind2 = triRef.fetchNextData(ind1);
	i2 = triRef.fetchData(ind2);
	while (ind1 != ind) {
	    Basic.vectorSub((Tuple3f) triRef.vertices[i2], (Tuple3f) triRef.vertices[i1], pr);
	    Basic.vectorProduct(pq, pr, nr);
	    d = Basic.lengthL2(nr);
	    if (Numerics.gt(d, Triangulator.ZERO))  {
		Basic.divScalar(d, nr);
		if (Basic.dotProduct(normal, nr) < 0.0) {
		    Basic.invertVector(nr);
		}
		Basic.vectorAdd(normal, nr, normal);
	    }
	    pq.set(pr);
	    ind1 = ind2;
	    ind2 = triRef.fetchNextData(ind1);
	    i2 = triRef.fetchData(ind2);
	}

	d = Basic.lengthL2(normal);
	if (Numerics.gt(d, Triangulator.ZERO)) {
	    Basic.divScalar(d, normal);
	}
	else {
	    //System.out.println("*** DetermineNormal: zero-length normal vector!? ***\n");
	    normal.x = normal.y = 0.0f; normal.z = 1.0f;

	}
    }


    /**
     * This function maps the vertices of the polygon referenced by `ind' to the
     * plane  n3.x * x + n3.y * y + n3.z * z = 0. every mapped vertex  (x,y,z)
     * is then expressed in terms of  (x',y',z'),  where  z'=0.  this is
     * achieved by transforming the original vertices into a coordinate system
     * whose z-axis coincides with  n3,  and whose two other coordinate axes  n1
     * and  n2  are orthonormal on  n3. note that n3 is supposed to be of unit
     * length!
     */
    static void projectPoints(Triangulator triRef, int i1, int i2, Vector3f n3) {
	Matrix4f matrix = new Matrix4f();
	Point3f vtx = new Point3f();
	Vector3f n1, n2;
	double d;
	int ind, ind1;
	int i, j1;


	n1 = new Vector3f();
	n2 = new Vector3f();

	// choose  n1  and  n2  appropriately
	if ((Math.abs(n3.x) > 0.1)  || (Math.abs(n3.y) > 0.1)) {
	    n1.x = -n3.y;
	    n1.y =  n3.x;
	    n1.z =  0.0f;
	}
	else {
	    n1.x =  n3.z;
	    n1.z = -n3.x;
	    n1.y =  0.0f;
	}
	d = Basic.lengthL2(n1);
	Basic.divScalar(d, n1);
	Basic.vectorProduct(n1, n3, n2);
	d = Basic.lengthL2(n2);
	Basic.divScalar(d, n2);

	// initialize the transformation matrix
	matrix.m00 = n1.x;
	matrix.m01 = n1.y;
	matrix.m02 = n1.z;
	matrix.m03 = 0.0f;       // translation of the coordinate system
	matrix.m10 = n2.x;
	matrix.m11 = n2.y;
	matrix.m12 = n2.z;
	matrix.m13 = 0.0f;       // translation of the coordinate system
	matrix.m20 = n3.x;
	matrix.m21 = n3.y;
	matrix.m22 = n3.z;
	matrix.m23 = 0.0f;       // translation of the coordinate system
	matrix.m30 = 0.0f;
	matrix.m31 = 0.0f;
	matrix.m32 = 0.0f;
	matrix.m33 = 1.0f;

	// transform the vertices and store the transformed vertices in the array
	// `points'
	triRef.initPnts(20);
	for (i = i1;  i < i2;  ++i) {
	    ind = triRef.loops[i];
	    ind1 = ind;
	    j1 = triRef.fetchData(ind1);
	    matrix.transform((Point3f)triRef.vertices[j1], vtx);
	    j1 = triRef.storePoint(vtx.x, vtx.y);
	    triRef.updateIndex(ind1, j1);
	    ind1 = triRef.fetchNextData(ind1);
	    j1 = triRef.fetchData(ind1);
	    while (ind1 != ind) {
		matrix.transform(triRef.vertices[j1], vtx);
		j1 = triRef.storePoint(vtx.x, vtx.y);
		triRef.updateIndex(ind1, j1);
		ind1 = triRef.fetchNextData(ind1);
		j1 = triRef.fetchData(ind1);
	    }
	}
    }

}