public static void BuildRectangleMesh(MeshBuilder meshBuilder, 
	                                      float width,
	                                      float height, 
	                                      float wStart,
	                                      float hStart,
	                                      float amount) {
		float fullW;
		float fullH;
		
		if ( width >= height ) {
			fullH = height*amount;
			fullW = width-(height-fullH);
		}
		else {
			fullW = width*amount;
			fullH = height-(width-fullW);
		}

		meshBuilder.Resize(4, 6);
		meshBuilder.ResetIndices();
		
		meshBuilder.AddVertex(new Vector3(fullW,  fullH, 0));
		meshBuilder.AddVertex(new Vector3(fullW, fullH*hStart, 0)); 
		meshBuilder.AddVertex(new Vector3(fullW*wStart, fullH*hStart, 0));
		meshBuilder.AddVertex(new Vector3(fullW*wStart, fullH, 0));
		
		meshBuilder.AddTriangle(0, 1, 2);
		meshBuilder.AddTriangle(0, 2, 3);
		
		meshBuilder.AddRemainingUvs(Vector2.zero);
	}

	public static void BuildArcMesh(MeshBuilder meshBuilder,
	                               float innerRadius,
	                               float outerRadius,
	                               float startAngle,
	                               float endAngle,
	                               int steps) {
		float angleFull = endAngle - startAngle;
		float angleInc = angleFull / steps;
		float angle = startAngle;

		meshBuilder.Resize((steps+1)*2, steps*6);
		meshBuilder.ResetIndices ();

		for (int i = 0; i <= steps; ++i) {
			float uv = i/(float)steps;

			meshBuilder.AddVertex(GetArcPoint(innerRadius, angle));
			meshBuilder.AddVertex(GetArcPoint(outerRadius, angle));

			meshBuilder.AddUv(new Vector2(uv, 0));
			meshBuilder.AddUv(new Vector2(uv, 1));

			if ( i > 0 ) {
				int vi = meshBuilder.VertexIndex;
				meshBuilder.AddTriangle(vi-3, vi-4, vi-2);
				meshBuilder.AddTriangle(vi-1, vi-3, vi-2);
			}

			angle += angleInc;
		}
	}

	public void Generate(int chunkX, int chunkY, Map parent)	{
		MeshFilter filter = this.gameObject.GetComponent<MeshFilter> ();
		if (filter == null) {
			filter = this.gameObject.AddComponent<MeshFilter> ();
		}

		MeshRenderer rend = this.gameObject.GetComponent<MeshRenderer> ();
		if (rend == null) {
			rend = this.gameObject.AddComponent<MeshRenderer> ();
		}

		rend.material = parent.mapMaterial;

		MeshBuilder meshBuilder = new MeshBuilder();

		int startX = chunkX * 32;
		int startY = chunkY * 32;
		for (int i = startX; i < startX + 32; i++) {
			float xPos = TILE_SIZE * (i - startX);
			for (int j = startY; j < startY + 32; j++) {
				float yPos = TILE_SIZE * (j - startY);
				BuildTile(meshBuilder, new Vector3(xPos, 0, yPos), parent.getTile(i, j));
			}
		}

		this.GetComponent<MeshFilter> ().sharedMesh = meshBuilder.CreateMesh ();
		this.transform.position = new Vector3(chunkX * Map.ChunkSize * TILE_SIZE, 0, chunkY * Map.ChunkSize * TILE_SIZE);
	}

    MeshBuilder GenerateCurveTriangles(MeshBuilder meshBuilder, bool doubleTriangles = false)
    {
        int baseIndex = 0;
        int sizeX = 2;
        int sizeY = meshBuilder.Vertices.Count / 3 - 1;

        int vi = baseIndex;

        for (int y = 0; y < sizeY; y++, vi++) {
            for (int x = 0; x < sizeX; x++, vi++) {
                meshBuilder.AddTriangle (vi, vi + sizeX + 1, vi + 1);
                meshBuilder.AddTriangle (vi + 1, vi + sizeX + 1, vi + sizeX + 2);

                if (y == sizeY - 1) {
                    meshBuilder.AddTriangle (vi + sizeX + 1, baseIndex + x, vi + sizeX + 2);
                    meshBuilder.AddTriangle (baseIndex + x + 1, vi + sizeX + 2, baseIndex + x);
                }

                if (doubleTriangles) {
                    meshBuilder.AddTriangle (vi + 1, vi + sizeX + 1, vi);
                    meshBuilder.AddTriangle (vi + sizeX + 2, vi + sizeX + 1, vi + 1);

                    if (y == sizeY - 1) {
                        meshBuilder.AddTriangle (vi + sizeX + 2, baseIndex + x, vi + sizeX + 1);
                        meshBuilder.AddTriangle (baseIndex + x, vi + sizeX + 2, baseIndex + x + 1);
                    }
                }
            }
        }
        return meshBuilder;
    }

    void GenerateCubeMesh()
    {
        MeshBuilder meshBuilder = new MeshBuilder ();

        Vector3 upDir = Vector3.up * meshHeight;
        Vector3 rightDir = Vector3.right * meshWidth;
        Vector3 forwardDir = Vector3.forward * meshLength;

        Vector3 nearCorner = - 0.5f * (upDir + rightDir + forwardDir);
        Vector3 farCorner =  nearCorner + upDir + rightDir + forwardDir;

        BuildQuad (meshBuilder, nearCorner, forwardDir, rightDir, sizeX, sizeZ);
        BuildQuad (meshBuilder, nearCorner, rightDir, upDir, sizeX, sizeZ);
        BuildQuad (meshBuilder, nearCorner, upDir, forwardDir, sizeX, sizeZ);

        BuildQuad (meshBuilder, farCorner, -rightDir, -forwardDir, sizeX, sizeZ);
        BuildQuad (meshBuilder, farCorner, -upDir, -rightDir, sizeX, sizeZ);
        BuildQuad (meshBuilder, farCorner, -forwardDir, -upDir, sizeX, sizeZ);

        GetComponent<MeshFilter> ().mesh = meshBuilder.CreateMesh ();

        //Invoke ("Spherify", 3f);

        PrepareForVerticesAnimation ();
    }

        public MapMesh(MapCompiled map)
        {
            texture = new Texture("Images/wall.png");
            material = new ObjMaterial("Models/wall.mtl").Lookup("wall");
            colorGroups = new List<WallColorGroup>();

            var colorMap = new Dictionary<Color, MeshBuilder<VertexTNP3>>();
            foreach (var wall in map.Walls) {
                MeshBuilder<VertexTNP3> builder;
                if (!colorMap.TryGetValue(wall.Color, out builder)) {
                    builder = new MeshBuilder<VertexTNP3>();
                    colorMap.Add(wall.Color, builder);
                }

                for (int i = 0; i < wall.Verts1.Length-1; i++) makeQuads(wall, builder, i, i+1);
                if (wall.Shape == ShapeData.Closed) makeQuads(wall, builder, wall.Verts1.Length-1, 0);
            }

            foreach (var pair in colorMap) {
                WallColorGroup g;
                g.Color = pair.Key;
                g.Mesh = pair.Value.ToMesh().Compile();
                colorGroups.Add(g);
            }
        }

    void BuildQuad(MeshBuilder meshBuilder, Vector3 offset, Vector3 widthDirection, Vector3 lengthDirection)
    {
        Vector3 normal = Vector3.Cross(lengthDirection, widthDirection).normalized;

        //Set up the vertices and triangles:
        meshBuilder.Vertices.Add(offset);
        meshBuilder.Uvs.Add(new Vector2(0.0f, 0.0f));
        meshBuilder.Normals.Add(normal);

        meshBuilder.Vertices.Add(offset + lengthDirection);
        meshBuilder.Uvs.Add(new Vector2(0.0f, 1.0f));
        meshBuilder.Normals.Add(normal);

        meshBuilder.Vertices.Add(offset + lengthDirection + widthDirection);
        meshBuilder.Uvs.Add(new Vector2(1.0f, 1.0f));
        meshBuilder.Normals.Add(normal);

        meshBuilder.Vertices.Add(offset + widthDirection);
        meshBuilder.Uvs.Add(new Vector2(1.0f, 0.0f));
        meshBuilder.Normals.Add(normal);

        int startPoint = meshBuilder.Vertices.Count - 4;
        if(first){
        meshBuilder.AddTriangle(startPoint, startPoint + 1, startPoint + 2);
        meshBuilder.AddTriangle(startPoint, startPoint + 2, startPoint + 3);
        //first = false;
        }
    }

    void BuildQuad(MeshBuilder meshBuilder, Vector3 offset, Vector3 widthDir, Vector3 lengthDir, int sizeX, int sizeY)
    {
        Vector3 normal = Vector3.Cross (lengthDir, widthDir).normalized;

        float vx, vy;

        // Define vertices e triangulos
        for (int y = 0; y <= sizeY; y++) {
            for (int x = 0; x <= sizeX; x++) {
                vx = ((float) x / sizeX);
                vy = ((float) y / sizeY);

                meshBuilder.Vertices.Add (offset + vx * lengthDir + vy * widthDir);
                meshBuilder.UVs.Add (new Vector2(vx, vy));
                meshBuilder.Normals.Add (normal);
            }
        }

        int baseIndex = meshBuilder.Vertices.Count - (sizeX+1) * (sizeY+1);

        for (int vi = baseIndex, y = 0; y < sizeY; y++, vi++) {
            for (int x = 0; x < sizeX; x++, vi++) {
                meshBuilder.AddTriangle (vi, vi+1, vi+sizeX+2);
                meshBuilder.AddTriangle (vi, vi+sizeX+2, vi+sizeX+1);
            }
        }
    }

    //BuildQuad with vectors
    public static Mesh BuildQuad(MeshBuilder meshBuilder, Vector3 offset, Vector3 widthDir, Vector3 lengthDir)
    {
        Vector3 normal = Vector3.Cross(lengthDir, widthDir).normalized;

        meshBuilder.Vertices.Add(offset);
        meshBuilder.UVs.Add(new Vector2(0.0f, 0.0f));
        meshBuilder.Normals.Add(normal);

        meshBuilder.Vertices.Add(offset + lengthDir);
        meshBuilder.UVs.Add(new Vector2(0.0f, 1.0f));
        meshBuilder.Normals.Add(normal);

        meshBuilder.Vertices.Add(offset + lengthDir + widthDir);
        meshBuilder.UVs.Add(new Vector2(1.0f, 1.0f));
        meshBuilder.Normals.Add(normal);

        meshBuilder.Vertices.Add(offset + widthDir);
        meshBuilder.UVs.Add(new Vector2(1.0f, 0.0f));
        meshBuilder.Normals.Add(normal);

        int baseIndex = meshBuilder.Vertices.Count - 4;

        meshBuilder.AddTriangle(baseIndex, baseIndex + 1, baseIndex + 2);
        meshBuilder.AddTriangle(baseIndex, baseIndex + 2, baseIndex + 3);

        Mesh _CreatedMesh = meshBuilder.CreateMesh();
        _CreatedMesh.RecalculateNormals();
        return _CreatedMesh;
    }

    // Use this for initialization
    public override MeshBuilder AddToMeshBuilder(MeshBuilder meshBuilder = null)
    {
        if (meshBuilder == null)
        {
            meshBuilder = new MeshBuilder();
        }

        float heightPerVertice = tunnelHeight / (heightVerticesNumber-1);

        circleOrigin = tunnelOrigin;
        circleOrigin.y += tunnelHeight / 2f;

        for(int h = 0; h < heightVerticesNumber; h++)
        {
            if (h == heightVerticesNumber -1)
            {
                addVertices = false;
            }

            meshBuilder = base.AddToMeshBuilder(meshBuilder);

            circleOrigin.y -= heightPerVertice;
        }

        return meshBuilder;
    }

    //Build the mesh:
    public override Mesh BuildMesh()
    {
        //Create a new mesh builder:
        MeshBuilder meshBuilder = new MeshBuilder();

        ////one-segment cylinder (build two rings, one at the bottom and one at the top):
        //BuildRing(meshBuilder, m_RadialSegmentCount, Vector3.zero, m_Radius, 0.0f, false);
        //BuildRing(meshBuilder, m_RadialSegmentCount, Vector3.up * m_Height, m_Radius, 1.0f, true);

        //multi-segment cylinder:
        float heightInc = m_Height / m_HeightSegmentCount;

        for (int i = 0; i <= m_HeightSegmentCount; i++)
        {
            //centre position of this ring:
            Vector3 centrePos = Vector3.up * heightInc * i;

            //V coordinate is based on height:
            float v = (float)i / m_HeightSegmentCount;

            BuildRing(meshBuilder, m_RadialSegmentCount, centrePos, m_Radius, v, i > 0);
        }

        ////caps:
        //BuildCap(meshBuilder, Vector3.zero, true);
        //BuildCap(meshBuilder, Vector3.up * m_Height, false);

        return meshBuilder.CreateMesh();
    }

    //public virtual Mesh BuildMesh() {
    //    return new Mesh();
    //}
    public Mesh BuildMesh(GizmoMeshShape shape, GizmoType type) {  // SIMPLE CUBE!
        MeshBuilder meshBuilder = new MeshBuilder();

        if(shape == GizmoMeshShape.Cube) {
            meshBuilder = EditorGizmoMeshShapes.GetCubeMesh(meshBuilder);
            //BuildQuad(meshBuilder, new Vector3(-0.5f, -0.5f, -0.5f), Vector3.right, Vector3.up); // FRONT
            //BuildQuad(meshBuilder, new Vector3(-0.5f, -0.5f, 0.5f), Vector3.back, Vector3.up); // LEFT
            //BuildQuad(meshBuilder, new Vector3(-0.5f, 0.5f, 0.5f), Vector3.back, Vector3.right); // TOP
            //BuildQuad(meshBuilder, new Vector3(0.5f, -0.5f, 0.5f), Vector3.left, Vector3.up); // BACK
            //BuildQuad(meshBuilder, new Vector3(0.5f, -0.5f, -0.5f), Vector3.forward, Vector3.up); // RIGHT
            //BuildQuad(meshBuilder, new Vector3(-0.5f, -0.5f, 0.5f), Vector3.right, Vector3.back); // BOTTOM

            if(type != GizmoType.none) {
                collider = this.gameObject.AddComponent<BoxCollider>();
                collider.isTrigger = true;
            }
            
            if (gizmoMaterial == null) {
                gizmoMaterial = new Material(Shader.Find("Custom/CritterEditorGizmo"));
                //gizmoMaterial.renderQueue = 4000;
            }
            GetComponent<MeshRenderer>().material = gizmoMaterial;
        }
        else if(shape == GizmoMeshShape.Arrow) {
            EditorGizmoMeshShapes.GetArrowMesh(meshBuilder);

            if (type != GizmoType.none) {
                MeshCollider meshCollider = this.gameObject.AddComponent<MeshCollider>();
                meshCollider.sharedMesh = meshBuilder.CreateMesh();
                collider = meshCollider;
                //collider.isTrigger = true;
            }

            if (gizmoMaterial == null) {
                gizmoMaterial = new Material(Shader.Find("Custom/CritterEditorGizmo"));
                //gizmoMaterial.renderQueue = 4000;
            }
            GetComponent<MeshRenderer>().material = gizmoMaterial;
        }
        else if (shape == GizmoMeshShape.OmniArrow) {
            EditorGizmoMeshShapes.GetOmniArrowMesh(meshBuilder);

            if (type != GizmoType.none) {
                MeshCollider meshCollider = this.gameObject.AddComponent<MeshCollider>();
                meshCollider.sharedMesh = meshBuilder.CreateMesh();
                collider = meshCollider;
            }

            if (gizmoMaterial == null) {
                gizmoMaterial = new Material(Shader.Find("Custom/CritterEditorGizmo"));
                //gizmoMaterial.renderQueue = 4000;
            }
            GetComponent<MeshRenderer>().material = gizmoMaterial;
        }
        else {
            Debug.Log("No Gizmo Shape!!!");
        }

        return meshBuilder.CreateMesh();
    }

 private static void Shear(MeshBuilder builder, OpenBveApi.Math.Vector3 direction, OpenBveApi.Math.Vector3 shift, double ratio)
 {
     for (int i = 0; i < builder.Vertices.Length; i++) {
         double factor = ratio * OpenBveApi.Math.Vector3.Dot(builder.Vertices[i].SpatialCoordinates, direction);
         builder.Vertices[i].SpatialCoordinates += shift * factor;
         if (!builder.Vertices[i].Normal.IsNullVector()) {
             factor = ratio * OpenBveApi.Math.Vector3.Dot(builder.Vertices[i].Normal, shift);
             builder.Vertices[i].Normal -= direction * factor;
             if (!builder.Vertices[i].Normal.IsNullVector()) {
                 builder.Vertices[i].Normal.Normalize();
             }
         }
     }
     for (int i = 0; i < builder.FaceCount; i++) {
         for (int j = 0; j < builder.Faces[i].Vertices.Length; j++) {
             if (!builder.Faces[i].Vertices[j].Normal.IsNullVector()) {
                 double factor = ratio * OpenBveApi.Math.Vector3.Dot(builder.Faces[i].Vertices[j].Normal, shift);
                 builder.Faces[i].Vertices[j].Normal -= direction * factor;
                 if (!builder.Faces[i].Vertices[j].Normal.IsNullVector()) {
                     builder.Faces[i].Vertices[j].Normal.Normalize();
                 }
             }
         }
     }
 }

    //Build the mesh:
    public override Mesh BuildMesh()
    {
        //Create a new mesh builder:
        MeshBuilder meshBuilder = new MeshBuilder();

        //height segments need to be half m_RadialSegmentCount for the sphere to be even horizontally and vertically:
        int heightSegmentCount = m_RadialSegmentCount / 2;

        //the angle increment per height segment:
        float angleInc = Mathf.PI / heightSegmentCount;

        for (int i = 0; i <= heightSegmentCount; i++)
        {
            Vector3 centrePos = Vector3.zero;

            //calculate a height offset and radius based on a vertical circle calculation:
            centrePos.y = -Mathf.Cos(angleInc * i) * m_Radius;
            float radius = Mathf.Sin(angleInc * i) * m_Radius;

            float v = (float)i / heightSegmentCount;

            //build the ring:
            BuildRingForSphere(meshBuilder, m_RadialSegmentCount, centrePos, radius, v, i > 0);
        }

        return meshBuilder.CreateMesh();
    }

    void GenerateMesh()
    {
        float start_time = Time.time;

        NoiseGenerator gen = new NoiseGenerator();
        noise = gen.generateNoise(width,width,100);
        MeshBuilder builder = new MeshBuilder();

        Vector3 offset = new Vector3(0, 0, 0);

        for(int x = 0;x< width;x++){

            for(int z=0;z< width;z++){
                offset.z+= spacing;
                offset.y = noise[x * width + z] * Random.Range(-3,3);
                bool tri = x > 0 && z > 0;
                BuildQuadForGrid(builder,offset,new Vector2((1f/width)*x,(1f/width)*z),tri,width);
            }
            offset.x+= spacing;
            offset.z = 0;
        }

        if (terrainMesh != null)
        {
            Mesh mesh = builder.CreateMesh();
            mesh.RecalculateNormals();
            terrainMesh.sharedMesh = mesh;
        }

        float diff = Time.time - start_time;
        Debug.Log("ProceduralTerrain was generated in " + diff + " seconds.");
    }

        /// <summary>
        /// Initializes a new instance of the <see cref="MainViewModel"/> class.
        /// </summary>
        public MainViewModel()
        {
            // Create a model group
            var modelGroup = new Model3DGroup();

            // Create a mesh builder and add a box to it
            var meshBuilder = new MeshBuilder(false, false);
            meshBuilder.AddBox(new Point3D(0, 0, 1), 1, 2, 0.5);
            meshBuilder.AddBox(new Rect3D(0, 0, 1.2, 0.5, 1, 0.4));

            // Create a mesh from the builder (and freeze it)
            var mesh = meshBuilder.ToMesh(true);

            // Create some materials
            var greenMaterial = MaterialHelper.CreateMaterial(Colors.Green);
            var redMaterial = MaterialHelper.CreateMaterial(Colors.Red);
            var blueMaterial = MaterialHelper.CreateMaterial(Colors.Blue);
            var insideMaterial = MaterialHelper.CreateMaterial(Colors.Yellow);

            // Add 3 models to the group (using the same mesh, that's why we had to freeze it)
            modelGroup.Children.Add(new GeometryModel3D { Geometry = mesh, Material = greenMaterial, BackMaterial = insideMaterial });
            modelGroup.Children.Add(new GeometryModel3D { Geometry = mesh, Transform = new TranslateTransform3D(-2, 0, 0), Material = redMaterial, BackMaterial = insideMaterial });
            modelGroup.Children.Add(new GeometryModel3D { Geometry = mesh, Transform = new TranslateTransform3D(2, 0, 0), Material = blueMaterial, BackMaterial = insideMaterial });

            // Set the property, which will be bound to the Content property of the ModelVisual3D (see MainWindow.xaml)
            this.Model = modelGroup;
        }

    /// <summary>
    /// Builds a single quad based on a position offset and width and length vectors.
    /// </summary>
    /// <param name="meshBuilder">The mesh builder currently being added to.</param>
    /// <param name="offset">A position offset for the quad.</param>
    /// <param name="widthDir">The width vector of the quad.</param>
    /// <param name="lengthDir">The length vector of the quad.</param>
    public static void BuildQuad(MeshBuilder meshBuilder, Vector3 offset, Vector3 widthDir, Vector3 lengthDir) {
        Vector3 normal = Vector3.Cross(lengthDir, widthDir).normalized;

        meshBuilder.Vertices.Add(offset);
        meshBuilder.UVs.Add(new Vector2(0.0f, 0.0f));
        meshBuilder.Normals.Add(normal);

        meshBuilder.Vertices.Add(offset + lengthDir);
        meshBuilder.UVs.Add(new Vector2(0.0f, 1.0f));
        meshBuilder.Normals.Add(normal);

        meshBuilder.Vertices.Add(offset + lengthDir + widthDir);
        meshBuilder.UVs.Add(new Vector2(1.0f, 1.0f));
        meshBuilder.Normals.Add(normal);

        meshBuilder.Vertices.Add(offset + widthDir);
        meshBuilder.UVs.Add(new Vector2(1.0f, 0.0f));
        meshBuilder.Normals.Add(normal);

        //we don't know how many verts the meshBuilder is up to, but we only care about the four we just added:
        int baseIndex = meshBuilder.Vertices.Count - 4;

        meshBuilder.AddTriangle(baseIndex, baseIndex + 1, baseIndex + 2);
        meshBuilder.AddTriangle(baseIndex, baseIndex + 2, baseIndex + 3);
    }

    //Build the mesh:
    public override Mesh BuildMesh()
    {
        //Create a new mesh builder:
        MeshBuilder meshBuilder = new MeshBuilder();

        //calculate directional vectors for all 3 dimensions of the cube:
        Vector3 upDir = Vector3.up * m_Height;
        Vector3 rightDir = Vector3.right * m_Width;
        Vector3 forwardDir = Vector3.forward * m_Length;

        //calculate the positions of two corners opposite each other on the cube:

        //positions that will place the pivot at the corner of the cube:
        Vector3 nearCorner = Vector3.zero;
        Vector3 farCorner = upDir + rightDir + forwardDir;

        ////positions that will place the pivot at the centre of the cube:
        //Vector3 farCorner = (upDir + rightDir + forwardDir) / 2;
        //Vector3 nearCorner = -farCorner;

        //build the 3 quads that originate from nearCorner:
        BuildQuad(meshBuilder, nearCorner, forwardDir, rightDir);
        BuildQuad(meshBuilder, nearCorner, rightDir, upDir);
        BuildQuad(meshBuilder, nearCorner, upDir, forwardDir);

        //build the 3 quads that originate from farCorner:
        BuildQuad(meshBuilder, farCorner, -rightDir, -forwardDir);
        BuildQuad(meshBuilder, farCorner, -upDir, -rightDir);
        BuildQuad(meshBuilder, farCorner, -forwardDir, -upDir);

        //initialise the Unity mesh and return it:
        return meshBuilder.CreateMesh();
    }

	public override Mesh BuildMesh() {  // SIMPLE PLANE!
		MeshBuilder meshBuilder = new MeshBuilder();

		BuildQuad (meshBuilder, new Vector3(-0.5f, 0.0f, 0.5f), Vector3.back, Vector3.right); // TOP
		
		return meshBuilder.CreateMesh ();
	}

    public Mesh BuildSimplifiedConvexMesh()
    {
        var builder = new MeshBuilder();

        for (int i = 0; i < 64; i++)
        {
            int index = Random.Range(0, mesh.triangles.Length / 3) * 3;

            Vector3[] triangle = new Vector3[]
            {
                mesh.vertices[mesh.triangles[index + 0]],
                mesh.vertices[mesh.triangles[index + 1]],
                mesh.vertices[mesh.triangles[index + 2]]
            };

            Vector3[] norms = new Vector3[]
            {
                Vector3.up,
                Vector3.up,
                Vector3.up
            };

            Vector2[] uvs = new Vector2[]
            {
                mesh.uv[mesh.triangles[index + 0]],
                mesh.uv[mesh.triangles[index + 1]],
                mesh.uv[mesh.triangles[index + 2]]
            };

            builder.AddTriangleToMesh(triangle, norms, uvs);
        }

        return builder.Build();
    }