圆和多边形碰撞Libgdx

Question

是否有一种方法在Libgdx验证多边形和圆之间的碰撞?

我看到了Intersector类，但只发现了圆形和矩形的碰撞测试。其他多边形呢?

如果我需要手动操作，使用Libgdx的最佳方法是什么?

Answer 1

遗憾的是，我没有足够的声誉来评论，所以我添加了这个作为另一个答案…

Cristiano的优秀答案适用于检查圆是否与多边形的线段重叠，但是它不能检查更不寻常的情况，即圆完全包含在多边形中，如果一个快速移动的小圆与一个大多边形相撞，就可能发生这种情况。

我已经在下面重新粘贴了克里斯蒂亚诺的代码，并做了一个小的改变来解决这个问题…

public static boolean overlaps(Polygon polygon, Circle circle) {
    float []vertices=polygon.getTransformedVertices();
    Vector2 center=new Vector2(circle.x, circle.y);
    float squareRadius=circle.radius*circle.radius;
    for (int i=0;i<vertices.length;i+=2){
        if (i==0){
            if (Intersector.intersectSegmentCircle(new Vector2(vertices[vertices.length - 2], vertices[vertices.length - 1]), new Vector2(vertices[i], vertices[i + 1]), center, squareRadius))
                return true;
        } else {
            if (Intersector.intersectSegmentCircle(new Vector2(vertices[i-2], vertices[i-1]), new Vector2(vertices[i], vertices[i+1]), center, squareRadius))
                return true;
        }
    }
    return polygon.contains(circle.x, circle.y);
}

Answer 2

所以，我设法创建了一个圆形和多边形之间的碰撞测试方法。至少，它对我有用。

代码如下:

public boolean overlaps(Polygon polygon, Circle circle) {
    float []vertices=polygon.getTransformedVertices();
    Vector2 center=new Vector2(circle.x, circle.y);
    float squareRadius=circle.radius*circle.radius;
    for (int i=0;i<vertices.length;i+=2){
        if (i==0){
            if (Intersector.intersectSegmentCircle(new Vector2(vertices[vertices.length-2], vertices[vertices.length-1]), new Vector2(vertices[i], vertices[i+1]), center, squareRadius))
                return true;
        } else {
            if (Intersector.intersectSegmentCircle(new Vector2(vertices[i-2], vertices[i-1]), new Vector2(vertices[i], vertices[i+1]), center, squareRadius))
                return true;
        }
    }
    return false;
}

Answer 3

…并遵循菲尔·安德森的优秀答案，这是我的版本，它只是避免每次检查都创建新的Vector2，而是重用Vector2的静态实例。

public class PolygonUtil {
static final Vector2 center = new Vector2();
static final Vector2 vec1 = new Vector2();
static final Vector2 vec2 = new Vector2();
public static boolean overlaps(Polygon polygon, Circle circle) {
    float []vertices=polygon.getTransformedVertices();
    center.set(circle.x, circle.y);
    float squareRadius=circle.radius*circle.radius;
    for (int i=0;i<vertices.length;i+=2){
        if (i==0){
            if (Intersector.intersectSegmentCircle(vec1.set(vertices[vertices.length - 2], vertices[vertices.length - 1]),
                    vec2.set(vertices[i], vertices[i + 1]), center, squareRadius))
                return true;
        } else {
            if (Intersector.intersectSegmentCircle(vec1.set(vertices[i-2], vertices[i-1]), vec2.set(vertices[i], vertices[i+1]), center, squareRadius))
                return true;
        }
    }
    return polygon.contains(circle.x, circle.y);
}

}