Gets a Point2D on the given CubicCurve2D at the parameterized position t. - Java 2D Graphics

Java examples for 2D Graphics:Curve

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Description

Gets a Point2D on the given CubicCurve2D at the parameterized position t.

Demo Code

/*//from  ww  w.jav a2 s. c o  m
 * Copyright (C) 2005 Jordan Kiang
 * jordan-at-kiang.org
 * 
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.

 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.

 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */
//package com.java2s;
import java.awt.geom.CubicCurve2D;
import java.awt.geom.Point2D;

public class Main {
    /**
     * Gets a Point2D on the given CubicCurve2D at the parameterized position t. 
     * 
     * @param curve the curve
     * @param t a parameterized t value along the length of the curve, 0-1 inclusive
     * @return the point
     */
    static public Point2D getPointOnCubicCurve(CubicCurve2D curve, double t) {
        if (null == curve) {
            throw new NullPointerException("curve must be non-null!");
        } else if (t < 0.0 || t > 1.0) {
            throw new IllegalArgumentException("t must be between 0 and 1!");
        }

        double ax = getCubicAx(curve);
        double bx = getCubicBx(curve);
        double cx = getCubicCx(curve);

        double ay = getCubicAy(curve);
        double by = getCubicBy(curve);
        double cy = getCubicCy(curve);

        double tSquared = t * t;
        double tCubed = t * tSquared;

        double x = (ax * tCubed) + (bx * tSquared) + (cx * t)
                + curve.getX1();
        double y = (ay * tCubed) + (by * tSquared) + (cy * t)
                + curve.getY1();

        return new Point2D.Double(x, y);
    }

    static private double getCubicAx(CubicCurve2D curve) {
        return curve.getX2() - curve.getX1() - getCubicBx(curve)
                - getCubicCx(curve);
    }

    static private double getCubicBx(CubicCurve2D curve) {
        return 3.0 * (curve.getCtrlX2() - curve.getCtrlX1())
                - getCubicCx(curve);
    }

    static private double getCubicCx(CubicCurve2D curve) {
        return 3.0 * (curve.getCtrlX1() - curve.getX1());
    }

    static private double getCubicAy(CubicCurve2D curve) {
        return curve.getY2() - curve.getY1() - getCubicBy(curve)
                - getCubicCy(curve);
    }

    static private double getCubicBy(CubicCurve2D curve) {
        return 3.0 * (curve.getCtrlY2() - curve.getCtrlY1())
                - getCubicCy(curve);
    }

    static private double getCubicCy(CubicCurve2D curve) {
        return 3.0 * (curve.getCtrlY1() - curve.getY1());
    }
}

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