engine/src/core/com/jme3/math/Triangle.java

/*
 * Copyright (c) 2009-2010 jMonkeyEngine
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * * Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 *
 * * Redistributions 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.
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 * * Neither the name of 'jMonkeyEngine' nor the names of its contributors
 *   may be used to endorse or promote products derived from this software
 *   without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
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 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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 */
package com.jme3.math;

import com.jme3.export.JmeExporter;
import com.jme3.export.JmeImporter;
import com.jme3.export.Savable;
import java.io.IOException;

/**
 * <code>Triangle</code> defines an object for containing triangle information.
 * The triangle is defined by a collection of three {@link Vector3f}
 * objects.
 * 
 * @author Mark Powell
 * @author Joshua Slack
 */
public class Triangle extends AbstractTriangle implements Savable, java.io.Serializable {

    static final long serialVersionUID = 1;

    private Vector3f pointa = new Vector3f();
    private Vector3f pointb = new Vector3f();
    private Vector3f pointc = new Vector3f();
    private transient Vector3f center;
    private transient Vector3f normal;
    private float projection;
    private int index;

    public Triangle() {
    }

    /**
     * Constructor instantiates a new <Code>Triangle</code> object with the
     * supplied vectors as the points. It is recommended that the vertices
     * be supplied in a counter clockwise winding to support normals for a
     * right handed coordinate system.
     * @param p1 the first point of the triangle.
     * @param p2 the second point of the triangle.
     * @param p3 the third point of the triangle.
     */
    public Triangle(Vector3f p1, Vector3f p2, Vector3f p3) {
        pointa.set(p1);
        pointb.set(p2);
        pointc.set(p3);
    }

    /**
     *
     * <code>get</code> retrieves a point on the triangle denoted by the index
     * supplied.
     * @param i the index of the point.
     * @return the point.
     */
    public Vector3f get(int i) {
        switch (i) {
            case 0:
                return pointa;
            case 1:
                return pointb;
            case 2:
                return pointc;
            default:
                return null;
        }
    }

    public Vector3f get1() {
        return pointa;
    }

    public Vector3f get2() {
        return pointb;
    }

    public Vector3f get3() {
        return pointc;
    }

    /**
     *
     * <code>set</code> sets one of the triangle's points to that specified as
     * a parameter.
     * @param i the index to place the point.
     * @param point the point to set.
     */
    public void set(int i, Vector3f point) {
        switch (i) {
            case 0:
                pointa.set(point);
                break;
            case 1:
                pointb.set(point);
                break;
            case 2:
                pointc.set(point);
                break;
        }
    }

    /**
     *
     * <code>set</code> sets one of the triangle's points to that specified as
     * a parameter.
     * @param i the index to place the point.
     */
    public void set(int i, float x, float y, float z) {
        switch (i) {
            case 0:
                pointa.set(x, y, z);
                break;
            case 1:
                pointb.set(x, y, z);
                break;
            case 2:
                pointc.set(x, y, z);
                break;
        }
    }

    public void set1(Vector3f v) {
        pointa.set(v);
    }

    public void set2(Vector3f v) {
        pointb.set(v);
    }

    public void set3(Vector3f v) {
        pointc.set(v);
    }

    public void set(Vector3f v1, Vector3f v2, Vector3f v3) {
        pointa.set(v1);
        pointb.set(v2);
        pointc.set(v3);
    }

    /**
     * calculateCenter finds the average point of the triangle. 
     *
     */
    public void calculateCenter() {
        if (center == null) {
            center = new Vector3f(pointa);
        } else {
            center.set(pointa);
        }
        center.addLocal(pointb).addLocal(pointc).multLocal(FastMath.ONE_THIRD);
    }

    /**
     * calculateNormal generates the normal for this triangle
     *
     */
    public void calculateNormal() {
        if (normal == null) {
            normal = new Vector3f(pointb);
        } else {
            normal.set(pointb);
        }
        normal.subtractLocal(pointa).crossLocal(pointc.x - pointa.x, pointc.y - pointa.y, pointc.z - pointa.z);
        normal.normalizeLocal();
    }

    /**
     * obtains the center point of this triangle (average of the three triangles)
     * @return the center point.
     */
    public Vector3f getCenter() {
        if (center == null) {
            calculateCenter();
        }
        return center;
    }

    /**
     * sets the center point of this triangle (average of the three triangles)
     * @param center the center point.
     */
    public void setCenter(Vector3f center) {
        this.center = center;
    }

    /**
     * obtains the unit length normal vector of this triangle, if set or
     * calculated
     * 
     * @return the normal vector
     */
    public Vector3f getNormal() {
        if (normal == null) {
            calculateNormal();
        }
        return normal;
    }

    /**
     * sets the normal vector of this triangle (to conform, must be unit length)
     * @param normal the normal vector.
     */
    public void setNormal(Vector3f normal) {
        this.normal = normal;
    }

    /**
     * obtains the projection of the vertices relative to the line origin.
     * @return the projection of the triangle.
     */
    public float getProjection() {
        return this.projection;
    }

    /**
     * sets the projection of the vertices relative to the line origin.
     * @param projection the projection of the triangle.
     */
    public void setProjection(float projection) {
        this.projection = projection;
    }

    /**
     * obtains an index that this triangle represents if it is contained in a OBBTree.
     * @return the index in an OBBtree
     */
    public int getIndex() {
        return index;
    }

    /**
     * sets an index that this triangle represents if it is contained in a OBBTree.
     * @param index the index in an OBBtree
     */
    public void setIndex(int index) {
        this.index = index;
    }

    public static Vector3f computeTriangleNormal(Vector3f v1, Vector3f v2, Vector3f v3, Vector3f store) {
        if (store == null) {
            store = new Vector3f(v2);
        } else {
            store.set(v2);
        }

        store.subtractLocal(v1).crossLocal(v3.x - v1.x, v3.y - v1.y, v3.z - v1.z);
        return store.normalizeLocal();
    }

    public void write(JmeExporter e) throws IOException {
        e.getCapsule(this).write(pointa, "pointa", Vector3f.ZERO);
        e.getCapsule(this).write(pointb, "pointb", Vector3f.ZERO);
        e.getCapsule(this).write(pointc, "pointc", Vector3f.ZERO);
    }

    public void read(JmeImporter e) throws IOException {
        pointa = (Vector3f) e.getCapsule(this).readSavable("pointa", Vector3f.ZERO.clone());
        pointb = (Vector3f) e.getCapsule(this).readSavable("pointb", Vector3f.ZERO.clone());
        pointc = (Vector3f) e.getCapsule(this).readSavable("pointc", Vector3f.ZERO.clone());
    }

    @Override
    public Triangle clone() {
        try {
            Triangle t = (Triangle) super.clone();
            t.pointa = pointa.clone();
            t.pointb = pointb.clone();
            t.pointc = pointc.clone();
            return t;
        } catch (CloneNotSupportedException e) {
            throw new AssertionError();
        }
    }
}