Libgdx 多边形三角剖分 [英] Libgdx polygon triangulation

问题描述

好的，所以我有一个多边形(简单但凹形)，我试图将它切割成三角形，以使其与另一个多边形相撞.

Ok, so I have a polygon (simple but concave) that I'm trying to cut into triangles to make it collide with an other polygon.

我知道我的多边形是凹的，所以我决定使用 LibGDX EarClippingTriangulator 将它切割成三角形.

I knew my polygone was concave, so i decided to use LibGDX EarClippingTriangulator to manage to cut it into triangles.

所以，通过这段代码，我得到了我的三角形顶点:

So, with this code, I get my triangles vertices :

public void triangulate()
    {
        Vector<float[]> trianglesVertices = new Vector<float[]>();
        ShortArray pointsCoords = new ShortArray();
        EarClippingTriangulator triangulator = new EarClippingTriangulator();

        // Cut in triangles
        pointsCoords = triangulator.computeTriangles(this.getTransformedVertices());

        // Make triangles
        for (int i = 0; i < pointsCoords.size / 6; i++)
        {
            trianglesVertices.add(new float[] {
                    pointsCoords.get(i), pointsCoords.get(i+1),
                    pointsCoords.get(i+2), pointsCoords.get(i+3),
                    pointsCoords.get(i+4), pointsCoords.get(i+5),
            });
            Polygon triangle = new Polygon(trianglesVertices.get(i));
            triangles.add(triangle);
        }

        System.out.printf("Triangulation made %d triangles.
", pointsCoords.size / 6);
    }

但是当我尝试绘制我刚刚制作的那些三角形时，他们只是堆叠在 0,0 坐标中..而且，所有三角形看起来几乎相同是否正常，我的意思是它们都有相同的方向?

But when i try to draw thoses triangles I just made, they just stack in the 0,0 coord.. And, is it normal that all triangles seems almost the sames, I mean they all got the same orientation ?

我没有找到太多关于这个用于 libgdx 的 trangulation 的信息你能帮忙吗?

I didn't found so much info about this trangulation use for libgdx Can you help ?

(对不起我的英语我是法国人，对不起没有照片，我在这里太年轻了)

(Sorry for my english i'm french, and sorry for no pictures, i'm too young here)

这是我的多边形(逆时针)

This is my polygon (in CCW)

hitbox.setVertices(new float[]{  
                this.getX() + 13, this.getY() - 60,
                this.getX() + 16, this.getY() - 74,
                this.getX() + 39, this.getY() - 74,
                this.getX() + 45, this.getY() - 105,
                this.getX() + 81, this.getY() - 105,
                this.getX() + 88, this.getY() - 74,
                this.getX() + 108, this.getY() - 74,
                this.getX() + 114, this.getY() - 61,
                this.getX() + 106, this.getY() - 30, // Top right
                this.getX() + 101, this.getY() - 29,
                this.getX() + 101, this.getY() - 57,
                this.getX() + 83, this.getY() - 62,
                this.getX() + 75, this.getY() - 50,
                this.getX() + 65, this.getY() - 4, // Top mid
                this.getX() + 62, this.getY() - 4, // Top mid
                this.getX() + 52, this.getY() - 50,
                this.getX() + 44, this.getY() - 62,
                this.getX() + 25, this.getY() - 56, 
                this.getX() + 25, this.getY() - 30,
                this.getX() + 19, this.getY() - 30,  // Top left
                });

现在我有足够的点来向您展示多边形了

Now i got enough point to show you the polygon here it is

推荐答案

问题出在你的循环上:

        // Make triangles
        for (int i = 0; i < pointsCoords.size / 6; i++)
        {
            trianglesVertices.add(new float[] {
                    pointsCoords.get(i), pointsCoords.get(i+1),
                    pointsCoords.get(i+2), pointsCoords.get(i+3),
                    pointsCoords.get(i+4), pointsCoords.get(i+5),
            });
            Polygon triangle = new Polygon(trianglesVertices.get(i));
            triangles.add(triangle);
        }

第一个三角形将具有正确的坐标，但第二个三角形将使用 pointsCoords 的 1、2、3、4、5、6 个元素，这些元素没有任何意义.您应该在循环内将 i 乘以 6 以考虑偏移:

First triangle will have correct coordinates, but second one will will use 1, 2, 3, 4, 5, 6 elements of pointsCoords that doesn't make any sence. You should multiply i by 6 inside loop to take offset into account:

                    pointsCoords.get(i*6), pointsCoords.get(i*6 + 1),
                    pointsCoords.get(i*6 + 2), pointsCoords.get(i*6 + 3),
                    pointsCoords.get(i*6 + 4), pointsCoords.get(i*6 + 5),

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