Read Vertices in a specific order?

Question

I need to read the vertices of a mesh in order from left to right, then backwards to forwards, but the order the vertices are read in are incredibly awkward. They seem to read clockwise around the edges then spiraling in towards the center. Sorry if it's hard to understand what i'm asking for, i've included a picture of the results i'm currently getting so hopefully that can help. My current code is listed below.

         //There is a "public int intensity" at the header to adjust the intensity (obviously) of the generation
 
         Mesh mesh = GetComponent<MeshFilter>().mesh;
         Vector3[] vertices = mesh.vertices;
         Vector3[] normals = mesh.normals;
            
         int i = 0;
         int step = 0;
         float lastY = 0;
          while (i < vertices.Length)
          {
             vertices[i] += new Vector3(vertices[i].x, Random.Range(lastY + -1,lastY + 1) * intensity, vertices[i].z);
             lastY = vertices[i].y;
             i++;
          }
          
         mesh.vertices = vertices;
         mesh.RecalculateNormals();
         mesh.RecalculateBounds();
         transform.gameObject.AddComponent<MeshCollider>();

alt text

Answer 1

The order of the vertices in a Mesh are determined by the order they were assigned when created. Unless explicitly documented by your importer or by the code which generated your mesh, there are no guarantees about the order of the vertices in the array.

Your picture looks like your mesh is a procedurally generated flat plane. To accomplish this with a specific order to the vertices, I recommend generating the mesh yourself. For example, to create a grid-based mesh, you can do something like the following:

 public class CreateMesh : MonoBehaviour {
     const int width = 100;
     const int height = 100;
     // Generate the mesh with a well-known vertex order
     void Start () {
         Mesh mesh = gameObject.AddComponent<MeshFilter>().mesh;
         gameObject.AddComponent<MeshRenderer>();
         mesh.vertices = GenerateVertices(width, height);
         mesh.triangles = GenerateTriangles(width, height);
     }
 
     private int[] GenerateTriangles(int width, int height)
     {
         //generate two triangles per vertex except the last column and last row
         int[] triangles = new int[(width - 1) * (height - 1) * 6];
         for (int y = 0; y < height - 1; y++ )
         {
             for (int x = 0; x < width - 1; x++ )
             {
                 triangles[(y * (width - 1) + x) * 6    ] = y * width + x;
                 triangles[(y * (width - 1) + x) * 6 + 1] = y * width + x + 1;
                 triangles[(y * (width - 1) + x) * 6 + 2] = y * width + x + 1 + width;
                 triangles[(y * (width - 1) + x) * 6 + 3] = y * width + x;
                 triangles[(y * (width - 1) + x) * 6 + 4] = y * width + x + 1 + width;
                 triangles[(y * (width - 1) + x) * 6 + 5] = y * width + x + width;
             }
         }
         return triangles;
     }
 
     Vector3[] GenerateVertices(int width, int height)
     {
         Vector3[] vertices = new Vector3[width * height];
         for (int y = 0; y < height; y++ )
         {
             for (int x = 0; x < width; x++ )
             {
                 vertices[y * width + x] = new Vector3(x / (float)width, y / (float) height);
             }
         }
         return vertices;
     }
     
     void Update () {
         Mesh mesh = this.gameObject.GetComponent<MeshFilter>().mesh;
         Vector3[] vertices = mesh.vertices;
         SetVertex(vertices, 10, 12, .55f);//set the z component of the vertex at x=10, y=12 to .55
         mesh.vertices = vertices;
     }
     private void SetVertex(Vector3[] verts, int x, int y, float z)
     {
         verts[width * y + x].z = z; 
     }
 }

Read Vertices in a specific order?

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