Evaluates the quadratic Bezier polynomial specified by the points p1, p2, and p3 for point t (0 <= t <= 1). - Java java.lang

Java examples for java.lang:Math Curve

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Description

Evaluates the quadratic Bezier polynomial specified by the points p1, p2, and p3 for point t (0 <= t <= 1).

Demo Code


//package com.java2s;
import static java.lang.Math.pow;
import java.awt.geom.Point2D;

public class Main {
    /**//from  w  w  w  .java2  s.com
     * Evaluates the quadric Bezier polynomial specified by the points p1, p2,
     * and p3 for point t (0 <= t <= 1).
     */
    public static Point2D quadCurve(Point2D p1, Point2D p2, Point2D p3,
            float t) {
        double b1 = bernsteinPolynomial(0, 2, t);
        double b2 = bernsteinPolynomial(1, 2, t);
        double b3 = bernsteinPolynomial(2, 2, t);

        double x = b1 * p1.getX() + b2 * p2.getX() + b3 * p3.getX();
        double y = b1 * p1.getY() + b2 * p2.getY() + b3 * p3.getY();

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

    /**
     * Returns the value of the Bernstein polynomial for the specified
     * parameters.
     */
    public static double bernsteinPolynomial(int i, int N, double t) {
        return fac(N) / (float) (fac(N - i) * fac(i)) * pow(1 - t, N - i)
                * pow(t, i);
    }

    /**
     * Returns the factorial of the specified number.
     * @param n the specified number.
     */
    public static int fac(int n) {
        if (n == 0) {
            return 1;
        } else {
            int result = 1;
            for (int i = 1; i <= n; i++) {
                result *= i;
            }

            return result;
        }
    }
}

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