@[TOC] (基础一)

初识基础：

1. 首先点和面的联系：三个点构成一个小三角形，然后面就是由无数的小三角形构成
   另外相同位置的顶点可以复用，就像一个正方形，四个点即可
   

2. 三角面有正反之分，关键看法线方向
   
   发现朝外的，我们能看到，反过来就看不到了，可以参考unity的Plane

3. uv： 纹理坐标
   目的是让我们的图片正确的显示到我们的图形上，也就是贴图吧
   取值范围就是0到1
   

4. 三角形序列（triangle）
   都是三点倍数

emmmm关于以上的一些基础知识的定义呢，可以考虑其他大佬写的
基础的定义

mesh学习

代码创建一个mesh

[RequireComponent(typeof(MeshFilter),typeof(MeshRenderer))]
public class Generate_Mesh1 : MonoBehaviour
{
    // Start is called before the first frame update
    void Start()
    {
        Mesh mesh = new Mesh();
        MeshFilter meshFilter = GetComponent<MeshFilter>();
        meshFilter.mesh = mesh;
        mesh.name = "lianxi1";
    }
}

RequireComponent表示在代码编译前需要先添加俩组件
上面代码创建一个空物体，把上面脚本拖上去即可

制作一个三角形面片

[RequireComponent(typeof(MeshFilter),typeof(MeshRenderer))]
public class Generate_Mesh1 : MonoBehaviour
{
    // Start is called before the first frame update
    void Start()
    {
        Mesh mesh = new Mesh();
        MeshFilter meshFilter = GetComponent<MeshFilter>();
        meshFilter.mesh = mesh;
        mesh.name = "lianxi1";
        mesh.vertices = GetVertex();
        mesh.triangles = GetTriangles();
    }

    private Vector3[] GetVertex()
    {
        return new Vector3[]
        {
            new Vector3(0,0,0),
            new Vector3(1,0,0),
            new Vector3(1,1,0)
        };
    }

    private int[] GetTriangles()
    {
        return new int[]
        {
            0,1,2
        };
    }
}

效果：

因为法线与摄像机方向相同了， 所以y轴旋转了180度
否则可以考虑GetTriangles 中的0，1，2 改成2，1，0

制作一个正方形

[RequireComponent(typeof(MeshFilter),typeof(MeshRenderer))]
public class Generate_Mesh1 : MonoBehaviour
{
    // Start is called before the first frame update
    void Start()
    {
        Mesh mesh = new Mesh();
        MeshFilter meshFilter = GetComponent<MeshFilter>();
        meshFilter.mesh = mesh;
        mesh.name = "lianxi1";
        mesh.RecalculateNormals();
        mesh.vertices = GetVertex();
        mesh.triangles = GetTriangles();
    }

    private Vector3[] GetVertex()
    {
        return new Vector3[]
        {
            new Vector3(0,0,0),
            new Vector3(1,0,0),
            new Vector3(1,1,0),
            new Vector3(0,1,0)
        };
    }

    private int[] GetTriangles()
    {
        return new int[]
        {
            2,1,0,
            0,3,2
        };
    }
}

效果：

注意

z轴（蓝色的）和摄像机z轴同向，即沿着摄像头，顺时针方向的三个点，才能被我们看到

UV设计

通过以上方法，创建完正方形或者其他图形，拖上材质球，你会发现
图形并不能完全显示

所以就涉及到了UV

[RequireComponent(typeof(MeshFilter),typeof(MeshRenderer))]
public class Generate_Mesh1 : MonoBehaviour
{
    // Start is called before the first frame update
    void Start()
    {
        Mesh mesh = new Mesh();
        MeshFilter meshFilter = GetComponent<MeshFilter>();
        meshFilter.mesh = mesh;
        mesh.name = "lianxi1";
        mesh.RecalculateNormals();
        mesh.vertices = GetVertex();
        mesh.triangles = GetTriangles();
        mesh.uv = GetUV();
    }

    private Vector3[] GetVertex()
    {
        return new Vector3[]
        {
            new Vector3(0,0,0),
            new Vector3(1,0,0),
            new Vector3(1,1,0),
            new Vector3(0,1,0)
        };
    }

    private int[] GetTriangles()
    {
        return new int[]
        {
            2,1,0,
            0,3,2
        };
    }

    private Vector2[] GetUV()
    {
        return new Vector2[]
        {
            new Vector2(0,0),
            new Vector2(1,0),
            new Vector2(1,1),
            new Vector2(0,1),
        };
    }
}

简单找个材质球拖上图片测试一下

如果显示上有点问题，应该是shader的问题 改成这个：

原图

UV上的坐标是怎么得到的呢

位置坐标也就是GetVertex中的四个顶点的坐标 因为我的物体坐标点方向账号和uv上的同向
或者我把GtVertex调整一下位置，注意观察GetUV：即顺序要保持一致

 private Vector3[] GetVertex()
    {
        return new Vector3[]
        {
            new Vector3(0,0,0),
            new Vector3(0,1,0),
            new Vector3(1,0,0),
            new Vector3(1,1,0)
            
        };
    }

    private int[] GetTriangles()
    {
        return new int[]
        {
            0,1,3,
            3,2,0
        };
    }

    private Vector2[] GetUV()
    {
        return new Vector2[]
        {
            new Vector2(0,0),
            new Vector2(0,1),
            new Vector2(1,0),
            new Vector2(1,1),
        };
    }

设置法线

[RequireComponent(typeof(MeshFilter),typeof(MeshRenderer))]
public class Generate_Mesh1 : MonoBehaviour
{
    // Start is called before the first frame update
    void Start()
    {
        Mesh mesh = new Mesh();
        MeshFilter meshFilter = GetComponent<MeshFilter>();
        meshFilter.mesh = mesh;
        mesh.name = "lianxi1";
        mesh.RecalculateNormals();
        mesh.vertices = GetVertex();
        mesh.triangles = GetTriangles();
        mesh.uv = GetUV();
        mesh.normals = GetNormals();
    }

    private Vector3[] GetNormals()
    {
        return new Vector3[]{
             Vector3.forward,
              Vector3.forward,
               Vector3.forward,
               Vector3.forward
        };
    }

    private Vector3[] GetVertex()
    {
        return new Vector3[]
        {
            new Vector3(0,0,0),
            new Vector3(0,1,0),
            new Vector3(1,0,0),
            new Vector3(1,1,0)
            
        };
    }

    private int[] GetTriangles()
    {
        return new int[]
        {
            0,1,3,
            3,2,0
        };
    }

    private Vector2[] GetUV()
    {
        return new Vector2[]
        {
            new Vector2(0,0),
            new Vector2(0,1),
            new Vector2(1,0),
            new Vector2(1,1),
        };
    }
}

注意 GetNormals（） 法线数组的个数要和顶点的个数保持一致，即每个点的法线

网格切线： mesh.tangents

那么它有什么用呢，他具体影响的是法线贴图的显示

就是这种凹凸不平的贴图 具体发现贴图添加位置：

涉及代码：

 void Update()
    {
        mesh.tangents = GetTangents();
    }

    private Vector4[] GetTangents()
    {
        return new Vector4[]{
            tempTangent,
            tempTangent,
            tempTangent,
            tempTangent
        };
    }

其中 tempTangent 是一个public 的Vector4 变量 ，放到Update中是为了方便看变化

详细代码

[RequireComponent(typeof(MeshFilter),typeof(MeshRenderer))]
public class Generate_Mesh1 : MonoBehaviour
{
    public Vector4 tempTangent;
    // Start is called before the first frame update
    private Mesh mesh;
    void Start()
    {
        mesh = new Mesh();
        MeshFilter meshFilter = GetComponent<MeshFilter>();
        meshFilter.mesh = mesh;
        mesh.name = "lianxi1";
        mesh.RecalculateNormals();
        mesh.vertices = GetVertex();
        mesh.triangles = GetTriangles();
        mesh.uv = GetUV();
        mesh.normals = GetNormals();
        //mesh.RecalculateNormals();
    }

    void Update()
    {
        mesh.tangents = GetTangents();
    }

    private Vector4[] GetTangents()
    {
        return new Vector4[]{
            tempTangent,
            tempTangent,
            tempTangent,
            tempTangent
        };
    }

    //private Vector3[] GetNormals()
    //{
    //    return new Vector3[]{
    //         mesh.vertices[1] - mesh.vertices[0],
    //          mesh.vertices[2] - mesh.vertices[1],
    //           mesh.vertices[3] - mesh.vertices[2],
    //          mesh.vertices[0] - mesh.vertices[3]
    //    };
    //}
    private Vector3[] GetNormals()
    {
        return new Vector3[]{
             Vector3.back,
             Vector3.back,
             Vector3.back,
             Vector3.back
        };
    }

    private Vector3[] GetVertex()
    {
        return new Vector3[]
        {
            new Vector3(0,0,0),
            new Vector3(0,1,0),
            new Vector3(1,0,0),
            new Vector3(1,1,0)
            
        };
    }

    private int[] GetTriangles()
    {
        return new int[]
        {
            0,1,3,
            3,2,0
        };
    }

    private Vector2[] GetUV()
    {
        return new Vector2[]
        {
            new Vector2(0,0),
            new Vector2(0,1),
            new Vector2(1,0),
            new Vector2(1,1),
        };
    }
}