在 Unity 中创建二维圆形网格

Question

我目前有一个 "CreateMesh" 脚本，它可以作为一个对象的一个组件，带有网格渲染器和网格过滤器，并且二维网格是用多边形碰撞器创建的给定 "MeshType" 变量的网格设置为 "tri" 或 "box"（分别用于三角形和矩形网格。）我还想添加创建圆形网格的功能，但是根据一些研究我意识到这并不像我最初想的那么简单。但是我还没有找到任何有用的东西。

这是我的长方体和三角形网格的代码：

public float width = 5f;
public float height = 5f;

public string meshType;

public PolygonCollider2D polyCollider;

void Start()
{
    polyCollider = GetComponent<PolygonCollider2D>();
}

// Update is called once per frame
void Update () {
    if (meshType == "tri")
    {
        TriangleMesh(width, height);
    }
    if (meshType == "box")
    {
        BoxMesh(width, height);
    }

}

void TriangleMesh(float width, float height)
{
    MeshFilter mf = GetComponent<MeshFilter>();
    Mesh mesh = new Mesh();
    mf.mesh = mesh;

    //Verticies
    Vector3[] verticies = new Vector3[3]
    {
        new Vector3(0,0,0), new Vector3(width, 0, 0), new Vector3(0, height, 0)
    };

    //Triangles
    int[] tri = new int[3];

    tri[0] = 0;
    tri[1] = 2;
    tri[2] = 1;

    //normals
    Vector3[] normals = new Vector3[3];

    normals[0] = -Vector3.forward;
    normals[1] = -Vector3.forward;
    normals[2] = -Vector3.forward;

    //UVs
    Vector2[] uv = new Vector2[3];

    uv[0] = new Vector2(0, 0);
    uv[0] = new Vector2(1, 0);
    uv[0] = new Vector2(0, 1);

    //initialise
    mesh.vertices = verticies;
    mesh.triangles = tri;
    mesh.normals = normals;
    mesh.uv = uv;

    //setting up collider
    polyCollider.pathCount = 1;

    Vector2[] path = new Vector2[3]
    {
        new Vector2(0,0), new Vector2(0, height), new Vector2(width, 0)
    };

    polyCollider.SetPath(0, path);

}

void BoxMesh(float width, float height)
{
    MeshFilter mf = GetComponent<MeshFilter>();
    Mesh mesh = new Mesh();
    mf.mesh = mesh;

    //Verticies
    Vector3[] verticies = new Vector3[4]
    {
        new Vector3(0,0,0), new Vector3(0, height, 0), new Vector3(width, height, 0), new Vector3(width, 0, 0)
    };

    //Triangles
    int[] tri = new int[6];

    tri[0] = 0;
    tri[1] = 1;
    tri[2] = 3;

    tri[3] = 1;
    tri[4] = 2;
    tri[5] = 3;

    //normals
    Vector3[] normals = new Vector3[4];

    normals[0] = -Vector3.forward;
    normals[1] = -Vector3.forward;
    normals[2] = -Vector3.forward;
    normals[3] = -Vector3.forward;

    //UVs
    Vector2[] uv = new Vector2[4];

    uv[0] = new Vector2(0, 0);
    uv[1] = new Vector2(0, 1);
    uv[2] = new Vector2(1, 1);
    uv[3] = new Vector2(1, 0);

    //initialise
    mesh.vertices = verticies;
    mesh.triangles = tri;
    mesh.normals = normals;
    mesh.uv = uv;

    //setting up collider
    polyCollider.pathCount = 1;

    Vector2[] path = new Vector2[4]
    {
        new Vector2(0,0), new Vector2(0, height), new Vector2(width, height), new Vector2(width, 0)
    };

    polyCollider.SetPath(0, path);

}

所以基本上我想要一个可以在更新方法中调用的函数，它只会创建一个圆形网格。例如：

void Update () {
   if (meshType == "tri")
   {
       TriangleMesh(width, height);
   }
   if (meshType == "box")
   {
       BoxMesh(width, height);
   }
   if (meshType == "circle")
   {
       CircleMesh(radius);
   }
}

Answer 1

我设法找到的解决方案是创建一个 n 边大且 n 值大的正多边形。我有一个名为 PolyMesh 的函数，它创建一个具有 n 边和给定半径的正多边形网格。

生成顶点

对于 n 边的正多边形的每个顶点，相对于多边形中心的坐标由 x = r*i*sin(θ) 和 y = r*i*cos(θ) 给出，因此 x = r*i*sin(2π/2) 和 y = r*i*cos(2π/2).其中 i 从 0 迭代到 n-1。因此，我们可以有一个列表，其中分配有顶点，然后转换为数组：

    //verticies
    List<Vector3> verticiesList = new List<Vector3> { };
    float x;
    float y;
    for (int i = 0; i < n; i ++)
    {
        x = radius * Mathf.Sin((2 * Mathf.PI * i) / n);
        y = radius * Mathf.Cos((2 * Mathf.PI * i) / n);
        verticiesList.Add(new Vector3(x, y, 0f));
    }
    Vector3[] verticies = verticiesList.ToArray();

生成三角形

一个给定的有n条边的正多边形可以从同一个点分成n-2个三角形。所以我们可以生成每个三角形如下：

    //triangles
    List<int> trianglesList = new List<int> { };
    for(int i = 0; i < (n-2); i++)
    {
        trianglesList.Add(0);
        trianglesList.Add(i+1);
        trianglesList.Add(i+2);
    }
    int[] triangles = trianglesList.ToArray();

生成法线

因为这是一个 2d 对象，我们可以将每个法线都设为 -Vector3.forward，如下所示：

    //normals
    List<Vector3> normalsList = new List<Vector3> { };
    for (int i = 0; i < verticies.Length; i++)
    {
        normalsList.Add(-Vector3.forward);
    }
    Vector3[] normals = normalsList.ToArray();

生成对撞机

我们可以只使用具有相同半径的圆形碰撞器，但为了使此函数适用于 n 值较小的多边形，我们必须使用 PolygonCollider2D。由于顶点数组中的顶点已经按顺序排列，我们可以简单地将它们用作 PolygonCollider2D.

的路径

    //polyCollider
    polyCollider.pathCount = 1;

    List<Vector2> pathList = new List<Vector2> { };
    for (int i = 0; i < n; i++)
    {
        pathList.Add(new Vector2(verticies[i].x, verticies[i].y));
    }
    Vector2[] path = pathList.ToArray();

    polyCollider.SetPath(0, path);

完整的代码应该是这样的：

public PolygonCollider2D polyCollider;

void Start()
{
    polyCollider = GetComponent<PolygonCollider2D>();
}

void PolyMesh(float radius, int n)
{
    MeshFilter mf = GetComponent<MeshFilter>();
    Mesh mesh = new Mesh();
    mf.mesh = mesh;

    //verticies
    List<Vector3> verticiesList = new List<Vector3> { };
    float x;
    float y;
    for (int i = 0; i < n; i ++)
    {
        x = radius * Mathf.Sin((2 * Mathf.PI * i) / n);
        y = radius * Mathf.Cos((2 * Mathf.PI * i) / n);
        verticiesList.Add(new Vector3(x, y, 0f));
    }
    Vector3[] verticies = verticiesList.ToArray();

    //triangles
    List<int> trianglesList = new List<int> { };
    for(int i = 0; i < (n-2); i++)
    {
        trianglesList.Add(0);
        trianglesList.Add(i+1);
        trianglesList.Add(i+2);
    }
    int[] triangles = trianglesList.ToArray();

    //normals
    List<Vector3> normalsList = new List<Vector3> { };
    for (int i = 0; i < verticies.Length; i++)
    {
        normalsList.Add(-Vector3.forward);
    }
    Vector3[] normals = normalsList.ToArray();

    //initialise
    mesh.vertices = verticies;
    mesh.triangles = triangles;
    mesh.normals = normals;

    //polyCollider
    polyCollider.pathCount = 1;

    List<Vector2> pathList = new List<Vector2> { };
    for (int i = 0; i < n; i++)
    {
        pathList.Add(new Vector2(verticies[i].x, verticies[i].y));
    }
    Vector2[] path = pathList.ToArray();

    polyCollider.SetPath(0, path);
}

An introduction to meshes

Answer 2

我的声望不到 50，所以我不能只评论@Tom Ryan 的回答。

尽管如此，请注意他的解决方案不包括网格的 UV。这是加法：

//uvs
Vector2[] uvs = new Vector2[vertices.Length];
for (int i = 0; i < uvs.Length; i++)
{
    uvs[i] = new Vector2(vertices[i].x / (radius*2) + 0.5f, vertices[i].y / (radius*2) + 0.5f);
}

// Later...
mesh.uv = uvs;

在 Unity 中创建二维圆形网格

Creating a 2D Circular Mesh in Unity

c#

mesh

unity3d