Mesh.Clear

Descripción

Limpia todos los datos de los índices de los vertices y los triángulos.

Deberías de invocar esta función antes de reconstruir el arreglo de triangles

// Convert any GameObject into a single triangle

using UnityEngine;

public class meshClear : MonoBehaviour
{
    private bool once = false;

    void Update()
    {
        if (Time.time > 2.0f)
        {
            convertMesh();
        }
    }

    void convertMesh()
    {
        if (once)
            return;

        Mesh mesh = GetComponent<MeshFilter>().mesh;

        // Clears all the data that the mesh currently has
        mesh.Clear();

        // create 3 vertices for the triangle
        mesh.vertices = new Vector3[] {new Vector3(0, 0, 0), new Vector3(0, 1, 0), new Vector3(1, 1, 0)};
        mesh.uv = new Vector2[] {new Vector2(0, 0), new Vector2(0, 1), new Vector2(1, 1)};
        mesh.triangles = new int[] {0, 1, 2};

        once = true;
    }
}

Default behaviour of this function keeps the existing vertex layout: if the mesh had tangent vectors and vertex colors, for example, then the tangents and colors will be part of mesh data once you fill in new vertex data. If you want to completely clear the mesh and start with an empty vertex layout, pass false for keepVertexLayout parameter. Alternatively, assigning an empty array to any mesh component will also remove it from the vertex layout.