com.github.mathiewz.slick.geom.Curve Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of modernized-slick Show documentation
The main purpose of this libraryis to modernize and maintain the slick2D library.
The newest version!
package com.github.mathiewz.slick.geom;

/**
 * A beizer curve implementation. The curve is defined by a start point, an end point
 * and two control points that it will tend towards. This is implementation is fixed
 * segmenting meaning it doesn't scale too well.
 *
 * @author kevin
 */
public class Curve extends Shape {
    /** The start point of the curve */
    private final Vector2f p1;
    /** The first control point */
    private final Vector2f c1;
    /** The second control point */
    private final Vector2f c2;
    /** The end point of the curve */
    private final Vector2f p2;
    /** The number of lines segments the curve is built out of */
    private final int segments;

    /**
     * Create a new curve with the default segments (20)
     *
     * @param p1
     *            The start of the curve
     * @param c1
     *            The first control point
     * @param c2
     *            The second control point
     * @param p2
     *            The end of the curve
     */
    public Curve(Vector2f p1, Vector2f c1, Vector2f c2, Vector2f p2) {
        this(p1, c1, c2, p2, 20);
    }

    /**
     * Create a new curve
     *
     * @param p1
     *            The start of the curve
     * @param c1
     *            The first control point
     * @param c2
     *            The second control point
     * @param p2
     *            The end of the curve
     * @param segments
     *            The number of segments to use
     */
    public Curve(Vector2f p1, Vector2f c1, Vector2f c2, Vector2f p2, int segments) {
        this.p1 = new Vector2f(p1);
        this.c1 = new Vector2f(c1);
        this.c2 = new Vector2f(c2);
        this.p2 = new Vector2f(p2);

        this.segments = segments;
        pointsDirty = true;
    }

    /**
     * Get the point at a particular location on the curve
     *
     * @param t
     *            A value between 0 and 1 defining the location of the curve the point is at
     * @return The point on the curve
     */
    public Vector2f pointAt(float t) {
        float a = 1 - t;
        float b = t;

        float f1 = a * a * a;
        float f2 = 3 * a * a * b;
        float f3 = 3 * a * b * b;
        float f4 = b * b * b;

        float nx = p1.getX() * f1 + c1.getX() * f2 + c2.getX() * f3 + p2.getX() * f4;
        float ny = p1.getY() * f1 + c1.getY() * f2 + c2.getY() * f3 + p2.getY() * f4;

        return new Vector2f(nx, ny);
    }

    /**
     * @see com.github.mathiewz.slick.geom.Shape#createPoints()
     */
    @Override
    protected void createPoints() {
        float step = 1.0f / segments;
        points = new Float[(segments + 1) * 2];
        for (int i = 0; i < segments + 1; i++) {
            float t = i * step;

            Vector2f p = pointAt(t);
            points[i * 2] = p.getX();
            points[i * 2 + 1] = p.getY();
        }
    }

    /**
     * @see com.github.mathiewz.slick.geom.Shape#transform(com.github.mathiewz.slick.geom.Transform)
     */
    @Override
    public Shape transform(Transform transform) {
        Float[] pts = new Float[8];
        Float[] dest = new Float[8];
        pts[0] = p1.getX();
        pts[1] = p1.getY();
        pts[2] = c1.getX();
        pts[3] = c1.getY();
        pts[4] = c2.getX();
        pts[5] = c2.getY();
        pts[6] = p2.getX();
        pts[7] = p2.getY();
        transform.transform(pts, 0, dest, 0, 4);

        return new Curve(new Vector2f(dest[0], dest[1]), new Vector2f(dest[2], dest[3]), new Vector2f(dest[4], dest[5]), new Vector2f(dest[6], dest[7]));
    }

    /**
     * True if this is a closed shape
     *
     * @return True if this is a closed shape
     */
    @Override
    public boolean closed() {
        return false;
    }
}