由于基础篇已经比较详细，此篇只贴代码。

平面圆形代码

圆形也是由三角形组成的，三角形个数越多则越园。

基类

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

[RequireComponent(typeof(MeshFilter),typeof(MeshRenderer))]
public class CreateMeshBase : MonoBehaviour
{
    MeshFilter meshFilter;

    protected Mesh mesh;

    protected virtual Vector3[] Vertices { get; }
    protected virtual int[] Triangles { get; }
    protected virtual Vector3[] Normals { get; }
    protected virtual Vector2[] Uvs { get; }
    protected virtual string MeshName { get; }

    protected virtual void Start()
    {
        GetMeshFilter();
    }

    protected virtual void Reset()
    {
        GetMeshFilter();
    }

    protected virtual void OnValidate()
    {
        GetMeshFilter();
    }

    void GetMeshFilter()
    {
        if (meshFilter == null)
        {
            meshFilter = GetComponent<MeshFilter>();
            mesh = new Mesh();            
        }

        mesh.triangles = null;
        mesh.uv = null;
        mesh.vertices = null;

        mesh.name = MeshName;
        mesh.vertices = Vertices;
        mesh.triangles = Triangles;
        mesh.uv = Uvs;

        meshFilter.mesh = mesh;
    }

    private void OnDrawGizmos()
    {
        if (Vertices == null) return;

        Gizmos.color = Color.red;
        Gizmos.DrawSphere(Vector3.zero, 0.5f);

        Gizmos.color = Color.blue;

        for (int i = 0; i < Vertices.Length; i++)
        {
            Gizmos.DrawSphere(Vertices[i], 0.3f);
        }
    }
}

圆形网格

其中triCount控制三角形个数，radius控制圆大小。

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class CreateCircle : CreateMeshBase
{
    [Range(3,100)]
    public int triCount = 6;
    public float radius = 5;
    public bool showHalf = false;

    protected override string MeshName
    {
        get
        {
            return "Circle Mesh";
        }
    }

    protected override Vector3[] Vertices
    {
        get
        {
            Vector3[] vertices = new Vector3[triCount + 1];
            vertices[0] = Vector3.zero;
            float angleDelta = 2 * Mathf.PI / triCount;

            for (int i = 0; i < triCount; i++)
            {
                float angle = angleDelta * i;
                float x = radius * Mathf.Cos(angle);
                float y = radius * Mathf.Sin(angle);

                vertices[i + 1] = new Vector3(x, y, 0);
            }

            return vertices;
        }
    }

    protected override int[] Triangles
    {
        get
        {
            int[] triangles = new int[triCount * 3];

            for (int i = 0; i < triCount; i++)
            {
                if (showHalf)
                {
                    if (i % 2 == 0) continue;
                }

                triangles[i * 3] = 0;
                triangles[i * 3 + 2] = i + 1;

                if (i + 2 > triCount)
                {
                    triangles[i * 3 + 1] = 1;
                }else
                {
                    triangles[i * 3 + 1] = i + 2;
                }
            }
            return triangles;
        }
    }

    protected override Vector2[] Uvs
    {
        get
        {
            Vector2[] uvs = new Vector2[triCount + 1];
            uvs[0] = new Vector2(0.5f,0.5f);
            float angleDelta = 2 * Mathf.PI / triCount;

            for (int i = 0; i < triCount; i++)
            {
                float angle = angleDelta * i;
                float x = Mathf.Cos(angle) * 0.5f + 0.5f;
                float y = Mathf.Sin(angle) * 0.5f + 0.5f;

                uvs[i + 1] = new Vector2(x, y);
            }
            return uvs;
        }
    }
}