Unity 顶点vertices，uv，与图片贴图，与mesh

mesh就是组成3d物体的三角形们。

mesh由顶点组成的三角形组成，三角形的大小 并不 需要一样，由顶点之间的位置决定。

mesh可以是一个或者多个面。

贴图的原点在左下角，uv是贴图的坐标，数量和顶点数一样（不是100%确定，比如前后左右4个面，贴图最终如何封闭，我还不知道），是贴图和顶点的对应关系。

新建空场景，把一下代码放到main camera：

using System;
using System.Collections;
using System.Collections.Generic;using UnityEngine;
#if UNITY_EDITOR
using UnityEditor;
#endifpublic class codeMesh2 : MonoBehaviour
{GUIStyle fontStyle = new GUIStyle();string msg = " - - ";// Start is called before the first frame updateVector3 center = new Vector3();GameObject o;bool ready = false;//int startCalled = 0;Camera c;string err = "";int moveRage = 25; int moveRage2 = 0;int moveRage2_1 = 0;Mesh mesh = null;public int width = 10;public int height = 10;public Texture aText = null;/// <summary>/// 上一次更新帧率的时间/// </summary>private float m_lastUpdateShowTime = 0f;/// <summary>/// 更新显示帧率的时间间隔/// </summary>private readonly float m_updateTime = 0.05f;/// <summary>/// 帧数/// </summary>private int m_frames = 0;/// <summary>/// 帧间间隔/// </summary>//private float m_frameDeltaTime = 0;private float m_FPS = 0;//private Rect m_fps, m_dtime;//顶点数组private Vector3[] vertices;//顶点法线private Vector3[] normals;private MeshFilter meshFilter;private int i = 0;private bool f = false;private string test2 = "";private int waitCount = 0;private void Awake(){Application.targetFrameRate = 30;moveRage2 = moveRage * 2;moveRage2_1 = moveRage * 2 - 1;fontStyle.normal.background = null;    //设置背景填充fontStyle.normal.textColor = Color.red;   //设置字体颜色fontStyle.fontSize = 40;fontStyle.wordWrap = true;c = GetComponent<Camera>();msg += " Waiting ";Vector3 v1 = new Vector3(5, 5, 5);Vector3 v2 = new Vector3(5, 5, 3);test2 = (v2 - v1).normalized.ToString();}void Start(){try{o = GenerateMeshTest1();center = c.transform.position;o.name = "d mesh";o.transform.position = new Vector3(-5, -5, 20);o.transform.localScale = new Vector3(10.0f, 10.0f, 10.0f);o.transform.rotation = Quaternion.Euler(new Vector3(0, 45, 45));m_lastUpdateShowTime = Time.realtimeSinceStartup;ready = true;}catch (Exception e){err = printException(e);}aText = Resources.Load("type/two_sizes") as Texture;o.GetComponent<MeshRenderer>().material.mainTexture = aText;#if UNITY_EDITORshowNormals();
#endif}private void OnGUI(){GUI.color = Color.red;msg = "fps=" + m_FPS + "/"+ Application.targetFrameRate +(err.Length>1?(", err=" + err):"")  + " waitCount = " + (ready? waitCount : (waitCount++));GUI.Label(new Rect(50, 10, 900, 100), "" + test2, fontStyle);GUI.Label(new Rect(100, 100, 900, 100), "[V07]：" + msg, fontStyle);}// Update is called once per framevoid Update(){if (!ready) return;int ri = i % (moveRage2);float x = ri - moveRage;if (!f){x = moveRage - ri;}if (ri == moveRage2_1){f = !f;}//o.transform.position = new Vector3(x, x, 20);//Debug.Log(x);//o.transform.rotation = Quaternion.Euler(new Vector3(0, 0, 0));/*Mesh mesh = o.GetComponent<MeshFilter>().mesh;//mesh.Clear();Vector3[] vertices = mesh.vertices;Vector3[] normals = mesh.normals;for (var i = 0; i < vertices.Length; i++){vertices[i] += normals[i] * Mathf.Sin(Time.time);}mesh.vertices = vertices;*/m_frames++;if (Time.realtimeSinceStartup - m_lastUpdateShowTime >= m_updateTime){m_FPS = m_frames / (Time.realtimeSinceStartup - m_lastUpdateShowTime);//m_frameDeltaTime = (Time.realtimeSinceStartup - m_lastUpdateShowTime) / m_frames;m_frames = 0;m_lastUpdateShowTime = Time.realtimeSinceStartup;//Debug.Log("FPS: " + m_FPS + "，间隔: " + m_FrameDeltaTime);}i++;}private GameObject GenerateMeshTest1(){GameObject obj = new GameObject();meshFilter = obj.AddComponent<MeshFilter>();//创建meshmesh = new Mesh();meshFilter.mesh = mesh;MeshRenderer renderer = obj.AddComponent<MeshRenderer>();//标准材质Material mat = new Material(Shader.Find("Legacy Shaders/Transparent/Diffuse"));mat.color = Color.white;renderer.material = mat;//创建顶点和UVvertices = new Vector3[6];Vector2[] uv = new Vector2[6];vertices[0] = new Vector3(0, 1, 0);//0vertices[1] = new Vector3(1, 1, 0);//1vertices[2] = new Vector3(1, 0, 0);//2vertices[3] = new Vector3(0, 0, 0);//3vertices[4] = new Vector3(0, 0, 1);//4vertices[5] = new Vector3(1, 0, 1);//5-int k = 0;uv[k++%6] = new Vector2(0, 1);uv[k++ % 6] = new Vector2(1, 1);uv[k++ % 6] = new Vector2(1, 0.5f);uv[k++ % 6] = new Vector2(0,0.5f);uv[k++ % 6] = new Vector2(0, 0);uv[k++ % 6] = new Vector2(1, 0);mesh.vertices = vertices;mesh.uv = uv;//mat.mainTexture = aText;int[] triangles = new int[12];k = 0;triangles[k++] = 3;triangles[k++] = 2;triangles[k++] = 5;triangles[k++] = 3;triangles[k++] = 5;triangles[k++] = 4; triangles[k++] = 0;triangles[k++] = 1;triangles[k++] = 2;triangles[k++] = 0;triangles[k++] = 2;triangles[k++] = 3;mesh.triangles = triangles; //三角面mesh.RecalculateNormals();  //计算法线/*Vector3[] normals = new Vector3[4];normals[0] = Vector3.back;normals[1] = Vector3.back;normals[2] = Vector3.back;normals[3] = Vector3.back;mesh.normals = normals;*///mesh.SetIndices//mat.SetTexture()return obj;}public static string printException(Exception e){return "\n\trs=" + e.HResult + ",\n\tmsg=" + e.Message + ",\n\tstack=" + e.StackTrace + "\n------------------------------------\n";}#if UNITY_EDITORprivate void showNormals(){if (mesh != null){//当前对象的操做从局部空间转换到世界空间 这样在下面的操作位置即可同步 否则位置是不会同步的Handles.matrix = meshFilter.transform.localToWorldMatrix;Handles.color = Color.green;int vertextCount = mesh.vertices.Length;//采用从顶点的位置[法线的起点】到法线的终点位置，既可以显示出当前顶点的法线for (int index = 0; index < vertextCount; index++){Handles.DrawLine(vertices[index], vertices[index] + normals[index]);}}}
#endif
}

two_sizes.png是一张 宽高比为1：2的图片。

三角形之间的定义顺序不会影响贴图。但单个三角形三个顶点是逆时针，则从外部可以看到贴图，从内部看不到。反之亦然：

（顺时针之后，从内部可见）

如果把图片直接放到场景，则两面都可见。