该文件只限于画2D的图形,在模仿Paper.io这个游戏时,遇到的问题,记录下,以供下次参考.
关于Unity中的网格过滤器,和网格渲染器,可以参考Unity的手册文档(请看文章最后).
这里简单说下我在模仿paper这个游戏的思路.
玩家在移动的过程中,会不断的更新位置,所以需要记录下玩家的点.并画在屏幕上,可以用Mesh Renderer,和Mesh Filter组件来渲染,然后初始化一个mesh对象,将其设置给Mesh Filter的相关属性.这个mesh就是负责画图的内容,他需要图形的顶点坐标,和三角形的顺序,而如果顶点数据复杂,计算三角形的顺序,就会变得繁琐,这个Triangulator刚好将这个过程封装了.只要给他传入一个顶点坐标数组,就能直接生成mesh需要的三角形数组出来,然后将顶点坐标,和三角形数组设置给mesh,即可显示我们需要的图形出来.
这里有个简单示例

void Start () {
        List<Vector2> vectors = new List<Vector2> ();

        vectors.Add (new Vector2 (0, 0));
        vectors.Add (new Vector2 (10, 0));
        vectors.Add (new Vector2 (10, 20));
        vectors.Add (new Vector2 (20, 20));
        vectors.Add (new Vector2 (20, 30));
        vectors.Add (new Vector2 (10, 30));
        vectors.Add (new Vector2 (0, 20));

        // Use the triangulator to get indices for creating triangles
        Triangulator tr = new Triangulator(vectors.ToArray());
        int[] indices = tr.Triangulate();

        // Create the Vector3 vertices
        Vector3[] vertices = new Vector3[vectors.Count];
        for (int i=0; i<vertices.Length; i++) {
            vertices[i] = new Vector3(vectors[i].x, vectors[i].y, 0);
        }

        // Create the mesh
        Mesh msh = new Mesh();
        msh.vertices = vertices;
        msh.triangles = indices;
        msh.RecalculateNormals();
        msh.RecalculateBounds();

        // Set up game object with mesh;
        gameObject.AddComponent(typeof(MeshRenderer));

        MeshFilter filter = gameObject.GetComponent<MeshFilter> ();
        if (filter == null) {
            filter = gameObject.AddComponent<MeshFilter>();
        }
        filter.mesh = msh;

    }

生成的内容就是这个样子

以下为Triangulator的完整代码

using UnityEngine;
using System.Collections.Generic;

public class Triangulator
{
    private List<Vector2> m_points = new List<Vector2>();

    public Triangulator (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;
        for (int m = 0, 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++;
                for (s = v, t = v + 1; t < nv; s++, t++)
                    V[s] = V[t];
                nv--;
                count = 2 * nv;
            }
        }

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

    private float Area () {
        int n = m_points.Count;
        float A = 0.0f;
        for (int p = n - 1, q = 0; 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;
        float 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 >= 0.0f) && (bCROSScp >= 0.0f) && (cCROSSap >= 0.0f));
    }
}

参考资料:
http://wiki.unity3d.com/index.php?title=Triangulator
https://docs.unity3d.com/ScriptReference/Mesh.html