MeshUtils.cs

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using UnityEngine;
using System.Collections;
using System.Collections.Generic;
 
/*
    Useful mesh functions
*/
public class MeshUtils : MonoBehaviour 
{
    // Finds a set of adjacent vertices for a given vertex
    // Note the success of this routine expects only the set of neighboring faces to eacn contain one vertex corresponding
    // to the vertex in question
    public static List<Vector3> findAdjacentNeighbors ( Vector3[] v, int[] t, Vector3 vertex )
    {
        List<Vector3>adjacentV = new List<Vector3>();
        List<int>facemarker = new List<int>();
        int facecount = 0;  
 
        // Find matching vertices
        for (int i=0; i<v.Length; i++)
            if (Mathf.Approximately (vertex.x, v[i].x) && 
                Mathf.Approximately (vertex.y, v[i].y) && 
                Mathf.Approximately (vertex.z, v[i].z))
            {
                    int v1 = 0;
                    int v2 = 0;
                    bool marker = false;
 
                    // Find vertex indices from the triangle array
                    for(int k=0; k<t.Length; k=k+3)
                        if(facemarker.Contains(k) == false)
                        {
                            v1 = 0;
                            v2 = 0;
                            marker = false;
 
                            if(i == t[k])
                            {
                                v1 = t[k+1];
                                v2 = t[k+2];
                                marker = true;
                            }
 
                            if(i == t[k+1])
                            {
                                v1 = t[k];
                                v2 = t[k+2];
                                marker = true;
                            }
 
                            if(i == t[k+2])
                            {
                                v1 = t[k];
                                v2 = t[k+1];
                                marker = true;
                            }
 
                            facecount++;
                            if(marker)
                            {
                                // Once face has been used mark it so it does not get used again
                                facemarker.Add(k);
 
                                // Add non duplicate vertices to the list
                                if ( isVertexExist(adjacentV, v[v1]) == false )
                                {   
                                    adjacentV.Add(v[v1]);
                                    //Debug.Log("Adjacent vertex index = " + v1);
                                }
 
                                if ( isVertexExist(adjacentV, v[v2]) == false )
                                {
                                    adjacentV.Add(v[v2]);
                                    //Debug.Log("Adjacent vertex index = " + v2);
                                }
                                marker = false;
                            }
                        }
            }
 
        //Debug.Log("Faces Found = " + facecount);
 
        return adjacentV;
    }
 
 
    // Finds a set of adjacent vertices indexes for a given vertex
    // Note the success of this routine expects only the set of neighboring faces to eacn contain one vertex corresponding
    // to the vertex in question
    public static List<int> findAdjacentNeighborIndexes ( Vector3[] v, int[] t, Vector3 vertex )
    {
        List<int>adjacentIndexes = new List<int>();
        List<Vector3>adjacentV = new List<Vector3>();
        List<int>facemarker = new List<int>();
        int facecount = 0;  
 
        // Find matching vertices
        for (int i=0; i<v.Length; i++)
            if (Mathf.Approximately (vertex.x, v[i].x) && 
                Mathf.Approximately (vertex.y, v[i].y) && 
                Mathf.Approximately (vertex.z, v[i].z))
            {
                    int v1 = 0;
                    int v2 = 0;
                    bool marker = false;
 
                    // Find vertex indices from the triangle array
                    for(int k=0; k<t.Length; k=k+3)
                        if(facemarker.Contains(k) == false)
                        {
                            v1 = 0;
                            v2 = 0;
                            marker = false;
 
                            if(i == t[k])
                            {
                                v1 = t[k+1];
                                v2 = t[k+2];
                                marker = true;
                            }
 
                            if(i == t[k+1])
                            {
                                v1 = t[k];
                                v2 = t[k+2];
                                marker = true;
                            }
 
                            if(i == t[k+2])
                            {
                                v1 = t[k];
                                v2 = t[k+1];
                                marker = true;
                            }
 
                            facecount++;
                            if(marker)
                            {
                                // Once face has been used mark it so it does not get used again
                                facemarker.Add(k);
 
                                // Add non duplicate vertices to the list
                                if ( isVertexExist(adjacentV, v[v1]) == false )
                                {   
                                    adjacentV.Add(v[v1]);
                                    adjacentIndexes.Add(v1);
                                    //Debug.Log("Adjacent vertex index = " + v1);
                                }
 
                                if ( isVertexExist(adjacentV, v[v2]) == false )
                                {
                                    adjacentV.Add(v[v2]);
                                    adjacentIndexes.Add(v2);
                                    //Debug.Log("Adjacent vertex index = " + v2);
                                }
                                marker = false;
                            }
                        }
            }
 
        //Debug.Log("Faces Found = " + facecount);
 
        return adjacentIndexes;
    }
 
    // Does the vertex v exist in the list of vertices
    static bool isVertexExist(List<Vector3>adjacentV, Vector3 v)
    {
        bool marker = false;
        foreach (Vector3 vec in adjacentV)
          if (Mathf.Approximately(vec.x,v.x) && Mathf.Approximately(vec.y,v.y) && Mathf.Approximately(vec.z,v.z))
          {
              marker = true;
              break;
          }
 
        return marker;
    }
}