Java判断点在多边形内算法

package algs.boundary;

/**
 * Author: areful
 * Date: 2018/8/9
 */
public class Boundary {
    private final BoundaryPoint[] points;

    Boundary(BoundaryPoint[] points) {
        this.points = points;
    }

    boolean contains(BoundaryPoint test) {
        boolean result = false;
        int i = 0;

        for (int j = this.points.length - 1; i < this.points.length; j = i++) {
            if (this.points[i].y > test.y != this.points[j].y > test.y
                    && test.x < (this.points[j].x - this.points[i].x) * (test.y - this.points[i].y) / (this.points[j].y - this.points[i].y) + this.points[i].x) {
                result = !result;
            }
        }

        return result;
    }
}

package algs.boundary;

/**
 * Author: areful
 * Date: 2018/8/9
 */
public class BoundaryPoint {
    public final double x;
    public final double y;

    public BoundaryPoint(double x, double y) {
        this.x = x;
        this.y = y;
    }
}