Mesh编程——三角形，多边形，正方体

基类：

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

public abstract class MeshDrawBase : MonoBehaviour
{
    protected MeshFilter targetFilter;
    protected Mesh mh;
    protected int[] tris;
    protected Vector2[] uvs;
    protected Vector3[] nornals;

    private void Awake()
    {
        targetFilter = GetComponent<MeshFilter>();
    }
    protected virtual void Update()
    {

    }
    protected abstract void DrawMesh();
}

 画出顶点：

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


public class MeshInfoImationPrint : MeshDrawBase
{
    protected override void DrawMesh()
    {

    }
    private void OnDrawGizmos()//编辑器模式调用
    {
        targetFilter = GetComponent<MeshFilter>();
        mh = targetFilter.sharedMesh;

        Gizmos.color = Color.red;
        for (int i = 0; i < mh.vertices.Length; i++)
        {
            Vector3 worldPoint = transform.TransformPoint(mh.vertices[i]);//局部坐标转成世界坐标
            Gizmos.DrawSphere(worldPoint, .1f);

        }
    }
}

 画三角形：

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
/// <summary>
/// 画三角形
/// </summary>
[RequireComponent(typeof(MeshFilter))]
[RequireComponent(typeof(MeshRenderer))]
public class TriangleDraw : MeshDrawBase
{
    public List<Vector3> vts = new List<Vector3>();

    private void Start()
    {
        mh = new Mesh();

        //获取顶点
        //世界坐标转换成局部坐标
        for (int i = 0; i < vts.Count; i++)
        {
            vts[i] = transform.InverseTransformPoint(vts[i]);
        }
        mh.vertices = vts.ToArray();

        //三角形
        tris = new int[3];
        tris[0] = 0;
        tris[1] = 1;
        tris[2] = 2;

        mh.triangles = tris;

        //uv
        uvs = new Vector2[vts.Count];
        uvs[0] = new Vector2(0, 0);
        uvs[1] = new Vector2(0, 1);
        uvs[2] = new Vector2(1, 0);

        mh.uv = uvs;

        mh.RecalculateBounds();
        mh.RecalculateNormals();//法线
        mh.RecalculateTangents();//切线

        targetFilter.mesh = mh;
    }
    protected override void DrawMesh()
    {


    }
}


画多边形：

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
/// <summary>
/// 画多边形
/// </summary>
[RequireComponent(typeof(MeshFilter))]//挂脚本时，自动添加组件
[RequireComponent(typeof(MeshRenderer))]
public class CreatManyTriabgle : MeshDrawBase
{
    private List<Vector3> vts = new List<Vector3>();

    protected override void DrawMesh()
    {


    }
    private void DrawPolygon()
    {
        mh = new Mesh();

        //顶点
        mh.vertices = vts.ToArray();
        //三角形
        int trislength = (vts.Count - 2) * 3;
        tris = new int[trislength];

        for (int i = 0,n=1; i < trislength; i+=3,n++)
        {
            tris[i] = 0;
            tris[i + 1] = n;
            tris[i + 2] = n + 1;
        }
        mh.triangles = tris;

        //法线
        nornals = new Vector3[vts.Count];
        for (int i = 0; i < vts.Count; i++)
        {
            nornals[i] = new Vector3(0, 0, 1);
        }
        mh.normals = nornals;

        mh.RecalculateBounds();
        mh.RecalculateTangents();

        targetFilter.mesh = mh;
    }
    protected override void Update()
    {
        base.Update();

        if (Input.GetMouseButtonDown(0))
        {
            Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
            RaycastHit hit;
            if(Physics.Raycast(ray,out hit, Mathf.Infinity))
            {
                Vector3 worldHitPoint = hit.point;
                //世界转成局部坐标
                Vector3 localHitPoint = transform.InverseTransformPoint(worldHitPoint);
                vts.Add(localHitPoint);
            }
        }

        if (Input.GetKeyDown(KeyCode.R))
        {
            Reset();
        }

        if (Input.GetKeyDown(KeyCode.S))
        {
           // Debug.LogError(111);
            DrawPolygon();
        }
    }
    private void Reset()//重置
    {
        vts.Clear();

        targetFilter.mesh = null;
        Destroy(mh);
    }

    private void OnGUI()//显示数字序号
    {
        if (vts.Count == 0) return;

        GUI.color = Color.red;

        for (int i = 0; i < vts.Count; i++)
        {
            Vector3 worldPoint = transform.TransformPoint(vts[i]);
            Vector3 screenPoint = Camera.main.WorldToScreenPoint(worldPoint);
            Vector3 uiPoint = new Vector3(screenPoint.x, Camera.main.pixelHeight - screenPoint.y, screenPoint.z);
            GUI.Label(new Rect(uiPoint, new Vector3(100, 80)), i.ToString());
        }
    }
    private void OnDrawGizmos()//画线
    {
        if (vts.Count == 0) return;

        Gizmos.color = Color.cyan;//金色

        for (int i = 0; i < vts.Count; i++)
        {
            //转成世界坐标
            Vector3 worldHitPoint = transform.TransformPoint(vts[i]);
            Gizmos.DrawSphere(worldHitPoint, .2f);
        }
    }
}

画正方体：

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
/// <summary>
/// 画正方体
/// </summary>
[RequireComponent(typeof(MeshFilter))]
[RequireComponent(typeof(MeshRenderer))]
public class DrawMeshCube : MeshDrawBase
{
    public List<Vector3> vts = new List<Vector3>();

    private void Start()
    {
        mh = new Mesh();
        //顶点
        mh.vertices = vts.ToArray();
        //三角形
        tris = new int[]
        {
            0,3,1,
            3,2,1,//下

            0,4,7,
            0,7,3,//前

            3,7,2,//右
            2,7,6,

            2,6,1,//后
            6,5,1,

            1,5,4,
            1,4,0,//左

            7,4,5,
            7,5,6//上
        };
        mh.triangles = tris;

        mh.RecalculateBounds();
        mh.RecalculateNormals();
        mh.RecalculateTangents();

        targetFilter.mesh = mh;
    }
    protected override void DrawMesh()
    {

    }

    private void OnDrawGizmos()
    {
        if (vts.Count == 0) return;
        Gizmos.color = Color.red;//点的颜色
        for (int i = 0; i < vts.Count; i++)
        {
            Vector3 worldPoint = transform.TransformPoint(vts[i]);//转成世界坐标
            Gizmos.DrawSphere(worldPoint, .1f);//画点
        }
    }
}