Raycast returns Bad Triangle Index after delete triangles in mesh

Questions & Answers
1

Hi,

I generate a mesh with many triangles.
I want to delete 2 triangles if i click them.
It works the first time, but if i try to hit the next triangle… the raycast triangleindex give me some wrong values.

  1. i select a triangle, detect the triangle to get the quad and i remove it.
    http://www.terabyte-unlimited.com/help1.png

I remove the triangles from the Mesh an safe ist

 public static void RemoveFace(GameObject ga, int tIndex)
    {
        Mesh tmpMesh = ga.GetComponent<MeshFilter>().mesh;
        MeshCollider tmpCol = ga.GetComponent<MeshCollider>();


        Vector3[] vertices = tmpMesh.vertices;
        Vector2[] uv = tmpMesh.uv;
        int[] triangles = tmpMesh.triangles;


        Vector3[] nVertices = new Vector3[vertices.Length - 4];
        Vector2[] nUV = new Vector2[nVertices.Length];
        int[] nTriangles = new int[triangles.Length - 6];


        int iC = 0;
        int[] TriIndex = new int[6];
        /*
        TriIndex[0] = triangles[tIndex * 3 + 0];
        TriIndex[1] = triangles[tIndex * 3 + 1];
        TriIndex[2] = triangles[tIndex * 3 + 2];
        if ((float)tIndex / 2.0f - Mathf.Floor((float)tIndex / 2.0f) > 0.0f)
        {
            TriIndex[3] = triangles[(tIndex - 1) * 3 + 0];
            TriIndex[4] = triangles[(tIndex - 1) * 3 + 1];
            TriIndex[5] = triangles[(tIndex - 1) * 3 + 2];
        }
        else
        {
            TriIndex[3] = triangles[(tIndex + 1) * 3 + 0];
            TriIndex[4] = triangles[(tIndex + 1) * 3 + 1];
            TriIndex[5] = triangles[(tIndex + 1) * 3 + 2];
        }

        for (int i = 0; i < vertices.Length; i++)
        {
            if (!TriIndex.Contains<int>(i))
            {
                nVertices[iC] = vertices*;*

nUV[iC] = uv*;*
iC++;
}
}
* */

TriIndex[0] = tIndex * 3 + 0;
TriIndex[1] = tIndex * 3 + 1;
TriIndex[2] = tIndex * 3 + 2;
if ((float)tIndex / 2.0f - Mathf.Floor((float)tIndex / 2.0f) > 0.0f)
{
TriIndex[3] = (tIndex - 1) * 3 + 0;
TriIndex[4] = (tIndex - 1) * 3 + 1;
TriIndex[5] = (tIndex - 1) * 3 + 2;
}
else
{
TriIndex[3] = (tIndex + 1) * 3 + 0;
TriIndex[4] = (tIndex + 1) * 3 + 1;
TriIndex[5] = (tIndex + 1) * 3 + 2;
}

iC = 0;
for (int i = 0; i < triangles.Length; i++)
{
if (!TriIndex.Contains(i))
{
nTriangles[iC] = triangles*;*
iC++;
}
}

tmpMesh.Clear();
tmpMesh.vertices = vertices;
tmpMesh.triangles = nTriangles;
tmpMesh.uv = uv;
tmpMesh.Optimize();
tmpMesh.RecalculateNormals();

tmpCol.sharedMesh = tmpMesh;
}
The two triangles are vanish… all fine…
*http://www.terabyte-unlimited.com/help2.png*_
If i try to raycast the next triangle, then i get some wrong triangleindex From the cast.
*http://www.terabyte-unlimited.com/help3.png*_
What can i do to get the right Triangle?
Something wrong with the mesh? Or with my Raycast?

2

Well i got it!
I will share my Function how remove a Quad (two triangles) with his vertices and uv and triangles.
Its cleaner than to remove only the triangles!

public static void RemoveFace(GameObject ga, int tIndex)
    {
        Mesh tmpMesh = ga.GetComponent<MeshFilter>().mesh;
        MeshCollider tmpCol = ga.GetComponent<MeshCollider>();


        Vector3[] vertices = tmpMesh.vertices;
        Vector2[] uv = tmpMesh.uv;
        int[] triangles = tmpMesh.triangles;


        Vector3[] nVertices = new Vector3[vertices.Length - 4];
        Vector2[] nUV = new Vector2[nVertices.Length];
        int[] nTriangles = new int[triangles.Length - 6];

        int[] sIndex = new int[4];
        sIndex[0] = triangles[tIndex * 3 + 0];
        sIndex[1] = triangles[tIndex * 3 + 1];
        sIndex[2] = triangles[tIndex * 3 + 2];
        if ((float)tIndex / 2.0f - Mathf.Floor((float)tIndex / 2.0f) > 0.0f)
           sIndex[3] =triangles[(tIndex - 1) * 3 + 0];
        else
           sIndex[3] =triangles[(tIndex + 1) * 3 + 1];


        int iC = 0;
        for (int i = 0; i < vertices.Length; i++)
        {
            if (i != sIndex[0] && i != sIndex[1] && i != sIndex[2] && i != sIndex[3])
            {
                nVertices[iC] = vertices*;*

nUV[iC] = uv*;*
iC++;
}
}

sIndex = new int[6];
sIndex[0] = tIndex * 3 + 0;
sIndex[1] = tIndex * 3 + 1;
sIndex[2] = tIndex * 3 + 2;
int heighestIndex = tIndex * 3 + 2;
if ((float)tIndex / 2.0f - Mathf.Floor((float)tIndex / 2.0f) > 0.0f)
{
sIndex[3] = (tIndex - 1) * 3 + 0;
sIndex[4] = (tIndex - 1) * 3 + 1;
sIndex[5] = (tIndex - 1) * 3 + 2;
}
else
{
sIndex[3] = (tIndex + 1) * 3 + 0;
sIndex[4] = (tIndex + 1) * 3 + 1;
sIndex[5] = (tIndex + 1) * 3 + 2;
heighestIndex=(tIndex + 1) * 3 + 2;
}
iC = 0;
for (int i = 0; i < triangles.Length; i++)
{
if (i != sIndex[0] && i != sIndex[1] && i != sIndex[2] && i != sIndex[3] && i != sIndex[4] && i != sIndex[5])
{
if (i > heighestIndex)
{
//vertices korrigieren
triangles -= 4;
}

nTriangles[iC] = triangles*;*
iC++;
}
}

tmpMesh.Clear();
tmpMesh.vertices = nVertices;
tmpMesh.triangles = nTriangles;
tmpMesh.uv = nUV;
tmpMesh.Optimize();
tmpMesh.RecalculateNormals();

tmpCol.sharedMesh = null;
tmpCol.sharedMesh = tmpMesh;
}