Unity Chunk

using UnityEngine;
using System.Collections;
using System.Collections.Generic;

public class World_Chunks : MonoBehaviour
{
    public List<MP_Chunk> thisChunk = new List<MP_Chunk>();

    IEnumerator Start()
    {
        GameObject.DestroyImmediate(GetComponent<MeshCollider>());
        GameObject.DestroyImmediate(GetComponent<MeshFilter>());

        gameObject.AddComponent<MeshCollider>();
        gameObject.AddComponent<MeshFilter>();

        for (int x = 0; x < World_ChunkLoader.instance.chunk_X_Width; x++)
        {
            for (int z = 0; z < World_ChunkLoader.instance.chunk_Z_Width; z++)
            {
                MP_Chunk tempchunk = new MP_Chunk();
                tempchunk.x        = x;
                tempchunk.y        = 0;
                tempchunk.z        = z;
                tempchunk.isFloor  = true;

                tempchunk.Color_Top     = new Color(1, 1, 1);
                tempchunk.Color_Bottom  = new Color(1, 1, 1);
                tempchunk.Color_Left    = new Color(1, 1, 1);
                tempchunk.Color_Right   = new Color(1, 1, 1);
                tempchunk.Color_Back    = new Color(1, 1, 1);
                tempchunk.Color_Front   = new Color(1, 1, 1);

                thisChunk.Add (tempchunk);
            }
        }

        yield return StartCoroutine (FloorkRender ());
    }

    IEnumerator FloorkRender()
    {
        Mesh          mesh      = GetComponent<MeshFilter>().mesh;
        List<Vector3> vertices  = new List<Vector3>();
        List<Vector2> uvs       = new List<Vector2>();
        List<int>     triangles = new List<int>();
        List<Color>   colors    = new List<Color>();
        int           vertexIndex;
        vertexIndex = 0;
        mesh.Clear();

        foreach(MP_Chunk tempchunk in thisChunk)
        {
            int Render_Top;
            int Render_Bottom;
            int Render_Left;
            int Render_Right;
            int Render_Front;
            int Render_Back;

            if(tempchunk.isFloor)
            {
                Render_Top = 1;
                Render_Bottom = 0;
                Render_Left = 0;
                Render_Right = 0;
                Render_Front = 0;
                Render_Back = 0;
            }
            else
            {
                if (BlockExist (tempchunk.x, tempchunk.y + 1, tempchunk.z)) {Render_Top = 0;}    else{Render_Top = 1;}
                if (BlockExist (tempchunk.x, tempchunk.y - 1, tempchunk.z)) {Render_Bottom = 0;} else{Render_Bottom = 1;}
                if (BlockExist (tempchunk.x - 1, tempchunk.y, tempchunk.z)) {Render_Left = 0;}   else{Render_Left = 1;}
                if (BlockExist (tempchunk.x + 1, tempchunk.y, tempchunk.z)) {Render_Right = 0;}  else{Render_Right = 1;}
                if (BlockExist (tempchunk.x, tempchunk.y, tempchunk.z + 1)) {Render_Front = 0;}  else{Render_Front = 1;}
                if (BlockExist (tempchunk.x, tempchunk.y, tempchunk.z - 1)) {Render_Back = 0;}   else{Render_Back = 1;}
            }

            if(Render_Top == 1)
            {
                vertices.Add(new Vector3(tempchunk.x    , tempchunk.y + 1, tempchunk.z    ));
                vertices.Add(new Vector3(tempchunk.x    , tempchunk.y + 1, tempchunk.z + 1));
                vertices.Add(new Vector3(tempchunk.x + 1, tempchunk.y + 1, tempchunk.z + 1));
                vertices.Add(new Vector3(tempchunk.x + 1, tempchunk.y + 1, tempchunk.z    ));

                colors.Add (tempchunk.Color_Top);
                colors.Add (tempchunk.Color_Top);
                colors.Add (tempchunk.Color_Top);
                colors.Add (tempchunk.Color_Top);

                // first triangle for the block top
                triangles.Add(vertexIndex);
                triangles.Add(vertexIndex+1);
                triangles.Add(vertexIndex+2);

                // second triangle for the block top
                triangles.Add(vertexIndex+2);
                triangles.Add(vertexIndex+3);
                triangles.Add(vertexIndex);

                // add UV
                uvs.Add(new Vector2(0, 0));
                uvs.Add(new Vector2(0, 1));
                uvs.Add(new Vector2(1, 1));
                uvs.Add(new Vector2(1, 0));
                vertexIndex += 4;
            }

            if(Render_Bottom == 1)
            {
                vertices.Add(new Vector3(tempchunk.x    , tempchunk.y, tempchunk.z    ));
                vertices.Add(new Vector3(tempchunk.x + 1, tempchunk.y, tempchunk.z    ));
                vertices.Add(new Vector3(tempchunk.x + 1, tempchunk.y, tempchunk.z + 1));
                vertices.Add(new Vector3(tempchunk.x    , tempchunk.y, tempchunk.z + 1));

                colors.Add (tempchunk.Color_Bottom);
                colors.Add (tempchunk.Color_Bottom);
                colors.Add (tempchunk.Color_Bottom);
                colors.Add (tempchunk.Color_Bottom);

                // first triangle for the block top
                triangles.Add(vertexIndex);
                triangles.Add(vertexIndex+1);
                triangles.Add(vertexIndex+2);

                // second triangle for the block top
                triangles.Add(vertexIndex+2);
                triangles.Add(vertexIndex+3);
                triangles.Add(vertexIndex);

                // add UV
                uvs.Add(new Vector2(0, 0));
                uvs.Add(new Vector2(0, 1));
                uvs.Add(new Vector2(1, 1));
                uvs.Add(new Vector2(1, 0));
                vertexIndex += 4;
            }

            if(Render_Left == 1)
            {
                vertices.Add(new Vector3(tempchunk.x, tempchunk.y    , tempchunk.z + 1));
                vertices.Add(new Vector3(tempchunk.x, tempchunk.y + 1, tempchunk.z + 1));
                vertices.Add(new Vector3(tempchunk.x, tempchunk.y + 1, tempchunk.z    ));
                vertices.Add(new Vector3(tempchunk.x, tempchunk.y    , tempchunk.z    ));

                colors.Add (tempchunk.Color_Left);
                colors.Add (tempchunk.Color_Left);
                colors.Add (tempchunk.Color_Left);
                colors.Add (tempchunk.Color_Left);

                // first triangle for the block top
                triangles.Add(vertexIndex);
                triangles.Add(vertexIndex+1);
                triangles.Add(vertexIndex+2);

                // second triangle for the block top
                triangles.Add(vertexIndex+2);
                triangles.Add(vertexIndex+3);
                triangles.Add(vertexIndex);

                // add UV
                uvs.Add(new Vector2(0, 0));
                uvs.Add(new Vector2(0, 1));
                uvs.Add(new Vector2(1, 1));
                uvs.Add(new Vector2(1, 0));
                vertexIndex += 4;
            }

            if(Render_Right == 1)
            {
                vertices.Add(new Vector3(tempchunk.x + 1, tempchunk.y    , tempchunk.z    ));
                vertices.Add(new Vector3(tempchunk.x + 1, tempchunk.y + 1, tempchunk.z    ));
                vertices.Add(new Vector3(tempchunk.x + 1, tempchunk.y + 1, tempchunk.z + 1));
                vertices.Add(new Vector3(tempchunk.x + 1, tempchunk.y    , tempchunk.z + 1));

                colors.Add (tempchunk.Color_Right);
                colors.Add (tempchunk.Color_Right);
                colors.Add (tempchunk.Color_Right);
                colors.Add (tempchunk.Color_Right);

                // first triangle for the block top
                triangles.Add(vertexIndex);
                triangles.Add(vertexIndex+1);
                triangles.Add(vertexIndex+2);

                // second triangle for the block top
                triangles.Add(vertexIndex+2);
                triangles.Add(vertexIndex+3);
                triangles.Add(vertexIndex);

                // add UV
                uvs.Add(new Vector2(0, 0));
                uvs.Add(new Vector2(0, 1));
                uvs.Add(new Vector2(1, 1));
                uvs.Add(new Vector2(1, 0));
                vertexIndex += 4;
            }

            if(Render_Front == 1)
            {
                vertices.Add(new Vector3(tempchunk.x    , tempchunk.y    , tempchunk.z + 1));
                vertices.Add(new Vector3(tempchunk.x + 1, tempchunk.y    , tempchunk.z + 1));
                vertices.Add(new Vector3(tempchunk.x + 1, tempchunk.y + 1, tempchunk.z + 1));
                vertices.Add(new Vector3(tempchunk.x    , tempchunk.y + 1, tempchunk.z + 1));

                colors.Add (tempchunk.Color_Front);
                colors.Add (tempchunk.Color_Front);
                colors.Add (tempchunk.Color_Front);
                colors.Add (tempchunk.Color_Front);

                // first triangle for the block top
                triangles.Add(vertexIndex);
                triangles.Add(vertexIndex+1);
                triangles.Add(vertexIndex+2);

                // second triangle for the block top
                triangles.Add(vertexIndex+2);
                triangles.Add(vertexIndex+3);
                triangles.Add(vertexIndex);

                // add UV
                uvs.Add(new Vector2(0, 0));
                uvs.Add(new Vector2(0, 1));
                uvs.Add(new Vector2(1, 1));
                uvs.Add(new Vector2(1, 0));
                vertexIndex += 4;
            }

            if(Render_Back == 1)
            {
                vertices.Add(new Vector3(tempchunk.x    , tempchunk.y    , tempchunk.z));
                vertices.Add(new Vector3(tempchunk.x    , tempchunk.y + 1, tempchunk.z));
                vertices.Add(new Vector3(tempchunk.x + 1, tempchunk.y + 1, tempchunk.z));
                vertices.Add(new Vector3(tempchunk.x + 1, tempchunk.y    , tempchunk.z));

                colors.Add (tempchunk.Color_Back);
                colors.Add (tempchunk.Color_Back);
                colors.Add (tempchunk.Color_Back);
                colors.Add (tempchunk.Color_Back);

                // first triangle for the block top
                triangles.Add(vertexIndex);
                triangles.Add(vertexIndex+1);
                triangles.Add(vertexIndex+2);

                // second triangle for the block top
                triangles.Add(vertexIndex+2);
                triangles.Add(vertexIndex+3);
                triangles.Add(vertexIndex);

                // add UV
                uvs.Add(new Vector2(0, 0));
                uvs.Add(new Vector2(0, 1));
                uvs.Add(new Vector2(1, 1));
                uvs.Add(new Vector2(1, 0));
                vertexIndex += 4;
            }
        }

        // Build the Mesh:
        mesh.vertices = vertices.ToArray();
        mesh.triangles = triangles.ToArray();
        mesh.colors = colors.ToArray ();
        mesh.uv = uvs.ToArray();
        //mesh.Optimize();
        mesh.RecalculateNormals();

        // update mesh collider
        GetComponent<MeshCollider>().sharedMesh = null;
        GetComponent<MeshCollider>().sharedMesh = mesh;
        yield return null;
    }

    bool BlockExist(int x, int y, int z)
    {
        foreach(MP_Chunk tempchunk in thisChunk)
        {
            if(tempchunk.x == x && tempchunk.y == y && tempchunk.z == z)
            {
                return true;
            }
        }
        return false;
    }

    public void ChangeColor(int iTriangle, Color iColor)
    {
        if(iTriangle % 2 == 1)
            iTriangle--;
        Mesh          mesh      = GetComponent<MeshFilter>().mesh;
        Color[] colors = mesh.colors;
        int iStart = mesh.triangles[iTriangle*3];
        for (int i = iStart; i < iStart+4; i++)
            colors[i] = iColor;
        mesh.colors = colors;
    }

    void Update()
    {
        int hx;
        int hy;
        int hz;

        if(Input.GetMouseButtonDown (0))
        {
            Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
            RaycastHit hit;
            if (Physics.Raycast(ray, out hit, 100))
            {
                if(this.name == hit.collider.gameObject.name)
                {
                    //Debug.Log ((Mathf.Floor(hit.point.x + (hit.normal.x/10)) - hit.collider.transform.position.x).ToString () + " - " + Mathf.Floor(hit.point.y + (hit.normal.y+2/10)).ToString () + " - " + Mathf.Floor(hit.point.z + (hit.normal.z/10)).ToString ());
                    hx = (int)Mathf.Floor((hit.point.x + (hit.normal.x/10) - hit.collider.transform.position.x));
                    hy = (int)Mathf.Floor((hit.point.y + (hit.normal.y/10) - hit.collider.transform.position.y)); // rounds down for accuracy
                    hz = (int)Mathf.Floor((hit.point.z + (hit.normal.z/10) - hit.collider.transform.position.z));

                    MP_Chunk tempchunk = new MP_Chunk();
                    tempchunk.x = hx;
                    tempchunk.y = hy;
                    tempchunk.z = hz;
                    tempchunk.isFloor = false;
                    tempchunk.Color_Top     = new Color(1, 1, 1);
                    tempchunk.Color_Bottom  = new Color(1, 1, 1);
                    tempchunk.Color_Left    = new Color(1, 1, 1);
                    tempchunk.Color_Right   = new Color(1, 1, 1);
                    tempchunk.Color_Back    = new Color(1, 1, 1);
                    tempchunk.Color_Front   = new Color(1, 1, 1);
                    thisChunk.Add (tempchunk);
                    StartCoroutine(FloorkRender ());
                }
            }
        }

        if(Input.GetMouseButtonDown (1))
        {
            Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
            RaycastHit hit;
            if (Physics.Raycast(ray, out hit, 100))
            {
                if(this.name == hit.collider.gameObject.name)
                {
                    //Debug.Log ((Mathf.Floor(hit.point.x + (hit.normal.x/10)) - hit.collider.transform.position.x).ToString () + " - " + Mathf.Floor(hit.point.y + (hit.normal.y+2/10)).ToString () + " - " + Mathf.Floor(hit.point.z + (hit.normal.z/10)).ToString ());
                    hx = (int)Mathf.Floor((hit.point.x + (hit.normal.x/10) - hit.collider.transform.position.x));
                    hy = (int)Mathf.Floor((hit.point.y + (hit.normal.y/10) - hit.collider.transform.position.y)); // rounds down for accuracy
                    hz = (int)Mathf.Floor((hit.point.z + (hit.normal.z/10) - hit.collider.transform.position.z));

                    //Debug.Log (hit.triangleIndex.ToString ());
                    foreach(MP_Chunk tempchunk in thisChunk)
                    {
                        if(tempchunk.x == hx && tempchunk.y == hy && tempchunk.z == hz)
                            Debug.Log ("Treffer");
                    }
                }
            }
        }

        if(World_ChunkLoader.instance.playerLoaded)
        {
            Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
            RaycastHit hit;
            if (Physics.Raycast(ray, out hit, 100))
            {
                if(this.name == hit.collider.gameObject.name)
                {
                    ChangeColor(hit.triangleIndex, new Color(0, 0, 0));
                }
            }
        }
    }
}

public class MP_Chunk
{
    public int       x;
    public int       y;
    public int       z;
    public bool      isFloor;

    public Color      Color_Top;
    public Color      Color_Bottom;
    public Color      Color_Left;
    public Color      Color_Right;
    public Color      Color_Front;
    public Color      Color_Back;
}