beziercurve.java

来自「java 3d game jme 工程开发源代码」· Java 代码 · 共 244 行

/*
 * Copyright (c) 2003-2009 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.
 *
 * * 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
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package com.jme.curve;

import com.jme.intersection.CollisionResults;
import com.jme.intersection.PickResults;
import com.jme.math.Matrix3f;
import com.jme.math.Ray;
import com.jme.math.Vector3f;
import com.jme.scene.Spatial;
import com.jme.util.geom.BufferUtils;

/**
 * <code>BezierCurve</code> uses an ordered-list of three-dimensional points
 * and the equation: x(t) = Sum(n, i=0) Bn,i(t)Pi <br>
 * t [0,1] <br>
 * Bn,i(t) = C(n;i)t^i(1-t)^(n-i) <br>
 * The input (t) provides the current point of the curve at a interval [0,1]
 * where 0 is the first control point and 1 is the second control point.
 * 
 * @author Mark Powell
 * @version $Id: BezierCurve.java,v 1.19 2006/05/11 19:40:52 nca Exp $
 */
public class BezierCurve extends Curve {

	private static final long serialVersionUID = 1L;

	private static Vector3f tempVect = new Vector3f();
	
	public BezierCurve() {
		super(null);
	}
	
	/**
	 * Constructor instantiates a new <code>BezierCurve</code> object.
	 * 
	 * @param name
	 *            the name of the scene element. This is required for
	 *            identification and comparision purposes.
	 */
	public BezierCurve(String name) {
		super(name);
	}

	/**
	 * Constructor instantiates a new <code>BezierCurve</code> object. The
	 * control points that define the curve are supplied.
	 * 
	 * @param name
	 *            the name of the scene element. This is required for
	 *            identification and comparision purposes.
	 * @param controlPoints
	 *            the points that define the curve.
	 */
	public BezierCurve(String name, Vector3f[] controlPoints) {
		super(name, controlPoints);
	}

	/**
	 * <code>getPoint</code> calculates a point on a Bezier curve from a given
	 * time value within the interval [0, 1]. If the value is zero or less, the
	 * first control point is returned. If the value is one or more, the last
	 * control point is returned. Using the equation of a Bezier Curve, the
	 * point at the interval is calculated and returned.
	 * 
	 * @see com.jme.curve.Curve#getPoint(float)
	 */
	public Vector3f getPoint(float time, Vector3f point) {
		//first point
		if (time < 0) {
		    BufferUtils.populateFromBuffer(point, getVertexBuffer(), 0);
			return point;
		}
		//last point.
		if (time > 1) {
		    BufferUtils.populateFromBuffer(point, getVertexBuffer(), getVertexCount() - 1);
			return point;
		}

		float muk = 1;
		float munk = (float) Math.pow(1 - time, getVertexCount() - 1);

		point.zero();

		for (int i = 0; i < getVertexCount(); i++) {
			int count = getVertexCount() - 1;
			int iCount = i;
			int diff = count - iCount;
			float blend = muk * munk;
			muk *= time;
			munk /= (1 - time);
			while (count >= 1) {
				blend *= count;
				count--;
				if (iCount > 1) {
					blend /= iCount;
					iCount--;
				}

				if (diff > 1) {
					blend /= diff;
					diff--;
				}
			}
			BufferUtils.populateFromBuffer(tempVect, getVertexBuffer(), i);
			point.x += tempVect.x * blend;
			point.y += tempVect.y * blend;
			point.z += tempVect.z * blend;
		}

		return point;
	}

	public Vector3f getPoint(float time) {
		return getPoint(time, new Vector3f());
	}

	/**
	 * <code>getOrientation</code> calculates the rotation matrix for any
	 * given point along to the line to still be facing in the direction of the
	 * line.
	 * 
	 * @param time
	 *            the current time (between 0 and 1)
	 * @param precision
	 *            how accurate to (i.e. the next time) to check against.
	 * @return the rotation matrix.
	 * @see com.jme.curve.Curve#getOrientation(float, float)
	 */
	public Matrix3f getOrientation(float time, float precision) {
		Matrix3f rotation = new Matrix3f();

		//calculate tangent
		Vector3f point = getPoint(time);
		Vector3f tangent = point.subtract(getPoint(time + precision));
		tangent = tangent.normalize();
		//calculate normal
		Vector3f tangent2 = getPoint(time - precision).subtract(point);
		Vector3f normal = tangent.cross(tangent2);
		normal = normal.normalize();
		//calculate binormal
		Vector3f binormal = tangent.cross(normal);
		binormal = binormal.normalize();

		rotation.setColumn(0, tangent);
		rotation.setColumn(1, normal);
		rotation.setColumn(2, binormal);
		return rotation;
	}

	/**
	 * <code>getOrientation</code> calculates the rotation matrix for any
	 * given point along to the line to still be facing in the direction of the
	 * line. A up vector is supplied, this keep the rotation matrix following
	 * the line, but insures the object's up vector is not drastically changed.
	 * 
	 * @param time
	 *            the current time (between 0 and 1)
	 * @param precision
	 *            how accurate to (i.e. the next time) to check against.
	 * @return the rotation matrix.
	 * @see com.jme.curve.Curve#getOrientation(float, float)
	 */
	public Matrix3f getOrientation(float time, float precision, Vector3f up) {
		if (up == null) {
			return getOrientation(time, precision);
		}
		Matrix3f rotation = new Matrix3f();

		//calculate tangent
		Vector3f tangent = getPoint(time).subtract(getPoint(time + precision));
		tangent = tangent.normalize();

		//calculate binormal
		Vector3f binormal = tangent.cross(up);
		binormal = binormal.normalize();

		//calculate normal
		Vector3f normal = binormal.cross(tangent);
		normal = normal.normalize();

		rotation.setColumn(0, tangent);
		rotation.setColumn(1, normal);
		rotation.setColumn(2, binormal);

		return rotation;
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see com.jme.scene.Spatial#hasCollision(com.jme.scene.Spatial,
	 *      com.jme.intersection.CollisionResults)
	 */
	public void findCollisions(Spatial scene, CollisionResults results) {
		// TODO Auto-generated method stub

	}
	
	public boolean hasCollision(Spatial scene, boolean checkTriangles) {
		return false;
	}

	/* (non-Javadoc)
	 * @see com.jme.scene.Spatial#doPick(com.jme.math.Ray, com.jme.intersection.PickResults)
	 */
	public void findPick(Ray toTest, PickResults results) {
		// TODO Auto-generated method stub
		
	}

}