Unity平面連續點組成的多邊形的網格化

網格化類的使用

僞代碼

List<Vector3> points;//空間點的集合
Triangulator triangulator = new Triangulator(points);
List<int> trigs =  new List<int>(triangulator.Triangulate());

List<Vector3> finalp = new List<Vector3>(points.ToArray());

mesh.vertices =  finalp.ToArray();
mesh.triangles =  trigs.ToArray();

網格化類的實現 Triangulator.cs

using System.Collections.Generic;
using UnityEngine;

public class Triangulator {

    private List<Vector2> m_points = new List<Vector2>();


    public Triangulator(List<Vector2> points)
    {
        initTriangulator(points.ToArray());
    }

    public Triangulator(List<Vector3> points)
    {
        m_points.Clear();
        for (int i = 0; i < points.Count; i++)
        {
            m_points.Add(new Vector2(points[i].x,points[i].y));
        }
    }


    public void initTriangulator (Vector2[] points) {
        m_points = new List<Vector2>(points);
    }

    public int[] Triangulate() {
        List<int> indices = new List<int>();

        int n = m_points.Count;
        if (n < 3)
            return indices.ToArray();

        int[] V = new int[n];
        if (Area() > 0) 
        {
            for (int v = 0; v < n; v++)
            V[v] = v;
        }
        else {
            for (int v = 0; v < n; v++)
                V[v] = (n - 1) - v;
        }

        int nv = n;
        int count = 2 * nv;
        var m=0;
        for (int v = nv - 1; nv > 2; ) 
        {
            if ((count--) <= 0)
                return indices.ToArray();

            int u = v;
            if (nv <= u)
                u = 0;
            v = u + 1;
            if (nv <= v)
                v = 0;
            int w = v + 1;
            if (nv <= w)
                w = 0;

            if (Snip(u, v, w, nv, V)) 
            {
                int a,b,c,s,t;
                a = V[u];
                b = V[v];
                c = V[w];
                indices.Add(a);
                indices.Add(b);
                indices.Add(c);
                m++;
                s = v;
                for (t = v + 1; t < nv; t++)
                {
                    V[s] = V[t];
                    s++;
                }
                nv--;
                count = 2 * nv;
            }
        }

        indices.Reverse();
        return indices.ToArray();
    }


    private float Area () {
        int n = m_points.Count;
        float A = 0.0f;
        int q=0;
        for (int p = n - 1; q < n; p = q++) {
            Vector2 pval = m_points[p];
            Vector2 qval = m_points[q];
            A += pval.x * qval.y - qval.x * pval.y;
        }
        return (A * 0.5f);
    }


    private bool Snip (int u, int v, int w, int n, int[] V) {
        int p;
        Vector2 A = m_points[V[u]];
        Vector2 B = m_points[V[v]];
        Vector2 C = m_points[V[w]];
        if (Mathf.Epsilon > (((B.x - A.x) * (C.y - A.y)) - ((B.y - A.y) * (C.x - A.x))))
            return false;
        for (p = 0; p < n; p++) {
            if ((p == u) || (p == v) || (p == w))
                continue;
            Vector2 P = m_points[V[p]];
            if (InsideTriangle(A, B, C, P))
                return false;
        }
        return true;
    }



    private bool InsideTriangle (Vector2 A, Vector2 B, Vector2 C, Vector2 P) {
        float ax,ay,bx,by,cx,cy,apx,apy,bpx,bpy,cpx,cpy,cCROSSap,bCROSScp,aCROSSbp;

        ax = C.x - B.x; ay = C.y - B.y;
        bx = A.x - C.x; by = A.y - C.y;
        cx = B.x - A.x; cy = B.y - A.y;
        apx = P.x - A.x; apy = P.y - A.y;
        bpx = P.x - B.x; bpy = P.y - B.y;
        cpx = P.x - C.x; cpy = P.y - C.y;

        aCROSSbp = ax * bpy - ay * bpx;
        cCROSSap = cx * apy - cy * apx;
        bCROSScp = bx * cpy - by * cpx;

        return ((aCROSSbp >= 0) && (bCROSScp >= 0) && (cCROSSap >= 0));
    }
}