NURBSFixedNTELSPointIterator.java

/*******************************************************************************
 * Copyright 2010 Simon Mieth
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 ******************************************************************************/

package org.kabeja.math;

import java.util.Iterator;



public class NURBSFixedNTELSPointIterator implements Iterator <Point3D>{
    private NURBS nurbs;
    private int ntels;
    private double dt = 0;
    private double t = 0;
    private int interval;
    private int lastInterval;

    /**
     *
     * @param nurbs
     *            The NURBS curve to draw
     * @param ntels
     *            the ntels per interval to use
     */
    public NURBSFixedNTELSPointIterator(NURBS nurbs, int ntels) {
        this.nurbs = nurbs;
        this.ntels = ntels;

        if (this.nurbs.getKnots().length == (this.nurbs.getDegree() +
                this.nurbs.controlPoints.length + 1)) {
            this.lastInterval = this.nurbs.getKnots().length -
                this.nurbs.getDegree() - 1;
            this.interval = this.nurbs.getDegree();
        } else if (this.nurbs.getKnots().length > 0) {
            // find self the start and end interval
            this.interval = 0;

            double start = this.nurbs.getKnots()[0];

            while (start == this.nurbs.getKnots()[this.interval + 1]) {
                this.interval++;
            }

            this.lastInterval = this.nurbs.getKnots().length - 1;

            double end = this.nurbs.getKnots()[this.lastInterval];

            while (end == this.nurbs.getKnots()[this.lastInterval]) {
                this.lastInterval--;
            }
        }

        //init t
        this.t = this.nurbs.getKnots()[this.nurbs.getDegree()];
        this.nextInterval();

        //fix for some broken nurbs
        if ((this.interval - 1) < this.nurbs.getDegree()) {
            this.interval = this.nurbs.getDegree() + 1;
        }
    }

    public boolean hasNext() {
        if (this.t < this.nurbs.getKnots()[this.interval]) {
            return true;
        } else if (this.interval < this.lastInterval) {
            this.nextInterval();

            return hasNext();
        }

        return false;
    }

    public Point3D next() {
        Point3D p = this.nurbs.getPointAt(this.interval - 1, t);
        //		System.out.println("t="+t);
        //		Point p = this.nurbs.getPointAt(t);
        this.t += this.dt;

        return p;
    }

    public void remove() {
        //nothing todo here
    }

    protected void nextInterval() {
        this.interval++;

        while ((this.t > this.nurbs.getKnots()[this.interval]) &&
                (this.interval < this.lastInterval)) {
            this.interval++;
        }

        double length = this.nurbs.getKnots()[this.interval] - this.t;
        this.dt = length / this.ntels;
    }
}