public void RegenerateVertexBuffer()
        {
            if (!ChunkPosition.HasValue)
            {
                return;
            }

            // Chunk nachladen
            if (chunk == null)
            {
                chunk = _manager.GetChunk(ChunkPosition.Value);
                if (chunk == null)
                {
                    return;
                }
            }

            List <VertexPositionNormalTexture> vertices = new List <VertexPositionNormalTexture>();
            List <int> index          = new List <int>();
            int        textureColumns = textures.Width / SceneControl.TEXTURESIZE;
            float      textureWidth   = 1f / textureColumns;

            // BlockTypes sammlen
            Dictionary <IBlockDefinition, int> textureOffsets = new Dictionary <IBlockDefinition, int>();
            // Dictionary<Type, BlockDefinition> definitionMapping = new Dictionary<Type, BlockDefinition>();
            int definitionIndex = 0;

            foreach (var definition in DefinitionManager.GetBlockDefinitions())
            {
                int textureCount = definition.Textures.Count();
                textureOffsets.Add(definition, definitionIndex);
                // definitionMapping.Add(definition.GetBlockType(), definition);
                definitionIndex += textureCount;
            }

            for (int z = 0; z < Chunk.CHUNKSIZE_Z; z++)
            {
                for (int y = 0; y < Chunk.CHUNKSIZE_Y; y++)
                {
                    for (int x = 0; x < Chunk.CHUNKSIZE_X; x++)
                    {
                        ushort block = chunk.GetBlock(x, y, z);
                        if (block == 0)
                        {
                            continue;
                        }

                        IBlockDefinition blockDefinition = DefinitionManager.GetBlockDefinitionByIndex(block);
                        if (blockDefinition == null)
                        {
                            continue;
                        }

                        int textureIndex;
                        if (!textureOffsets.TryGetValue(blockDefinition, out textureIndex))
                        {
                            continue;
                        }

                        // Textur-Koordinate "berechnen"
                        Vector2 textureOffset = new Vector2();
                        Vector2 textureSize   = new Vector2(textureWidth - 0.005f, textureWidth - 0.005f);


                        ushort           topBlock          = _manager.GetBlock((ChunkPosition.Value * Chunk.CHUNKSIZE) + new Index3(x, y, z + 1));
                        IBlockDefinition topBlockDefintion = DefinitionManager.GetBlockDefinitionByIndex(topBlock);

                        // Top
                        if (topBlock == 0 || (!topBlockDefintion.IsBottomSolidWall(_manager, x, y, z + 1) && topBlock != block))
                        {
                            textureOffset = new Vector2(
                                (((textureIndex + blockDefinition.GetTopTextureIndex(_manager, x, y, z)) % textureColumns) * textureWidth) + 0.002f,
                                (((textureIndex + blockDefinition.GetTopTextureIndex(_manager, x, y, z)) / textureColumns) * textureWidth) + 0.002f);

                            Vector2[] points = new[] {
                                textureOffset,
                                new Vector2(textureOffset.X + textureSize.X, textureOffset.Y),
                                textureOffset + textureSize,
                                new Vector2(textureOffset.X, textureOffset.Y + textureSize.X)
                            };
                            int rotation = -blockDefinition.GetTopTextureRotation(_manager, x, y, z);

                            int localOffset = vertices.Count;
                            vertices.Add(new VertexPositionNormalTexture(new Vector3(x + 0, y + 1, z + 1), new Vector3(0, 0, 1), points[(4 + rotation) % 4]));
                            vertices.Add(new VertexPositionNormalTexture(new Vector3(x + 1, y + 1, z + 1), new Vector3(0, 0, 1), points[(5 + rotation) % 4]));
                            vertices.Add(new VertexPositionNormalTexture(new Vector3(x + 0, y + 0, z + 1), new Vector3(0, 0, 1), points[(7 + rotation) % 4]));
                            vertices.Add(new VertexPositionNormalTexture(new Vector3(x + 1, y + 0, z + 1), new Vector3(0, 0, 1), points[(6 + rotation) % 4]));
                            index.Add(localOffset + 0);
                            index.Add(localOffset + 1);
                            index.Add(localOffset + 3);
                            index.Add(localOffset + 0);
                            index.Add(localOffset + 3);
                            index.Add(localOffset + 2);
                        }

                        ushort           bottomBlock          = _manager.GetBlock((ChunkPosition.Value * Chunk.CHUNKSIZE) + new Index3(x, y, z - 1));
                        IBlockDefinition bottomBlockDefintion = DefinitionManager.GetBlockDefinitionByIndex(bottomBlock);


                        // Unten
                        if (bottomBlock == 0 || (!bottomBlockDefintion.IsTopSolidWall(_manager, x, y, z - 1) && bottomBlock != block))
                        {
                            textureOffset = new Vector2(
                                (((textureIndex + blockDefinition.GetBottomTextureIndex(_manager, x, y, z)) % textureColumns) * textureWidth) + 0.002f,
                                (((textureIndex + blockDefinition.GetBottomTextureIndex(_manager, x, y, z)) / textureColumns) * textureWidth) + 0.002f);

                            Vector2[] points = new[] {
                                textureOffset,
                                new Vector2(textureOffset.X + textureSize.X, textureOffset.Y),
                                textureOffset + textureSize,
                                new Vector2(textureOffset.X, textureOffset.Y + textureSize.X)
                            };
                            int rotation = -blockDefinition.GetBottomTextureRotation(_manager, x, y, z);

                            int localOffset = vertices.Count;
                            vertices.Add(new VertexPositionNormalTexture(new Vector3(x + 1, y + 1, z + 0), new Vector3(0, 0, -1), points[(6 + rotation) % 4]));
                            vertices.Add(new VertexPositionNormalTexture(new Vector3(x + 0, y + 1, z + 0), new Vector3(0, 0, -1), points[(7 + rotation) % 4]));
                            vertices.Add(new VertexPositionNormalTexture(new Vector3(x + 1, y + 0, z + 0), new Vector3(0, 0, -1), points[(5 + rotation) % 4]));
                            vertices.Add(new VertexPositionNormalTexture(new Vector3(x + 0, y + 0, z + 0), new Vector3(0, 0, -1), points[(4 + rotation) % 4]));
                            index.Add(localOffset + 0);
                            index.Add(localOffset + 1);
                            index.Add(localOffset + 3);
                            index.Add(localOffset + 0);
                            index.Add(localOffset + 3);
                            index.Add(localOffset + 2);
                        }

                        ushort           southBlock          = _manager.GetBlock((ChunkPosition.Value * Chunk.CHUNKSIZE) + new Index3(x, y + 1, z));
                        IBlockDefinition southBlockDefintion = DefinitionManager.GetBlockDefinitionByIndex(southBlock);

                        // South
                        if (southBlock == 0 || (!southBlockDefintion.IsNorthSolidWall(_manager, x, y + 1, z) && southBlock != block))
                        {
                            textureOffset = new Vector2(
                                (((textureIndex + blockDefinition.GetSouthTextureIndex(_manager, x, y, z)) % textureColumns) * textureWidth) + 0.002f,
                                (((textureIndex + blockDefinition.GetSouthTextureIndex(_manager, x, y, z)) / textureColumns) * textureWidth) + 0.002f);

                            Vector2[] points = new[] {
                                textureOffset,
                                new Vector2(textureOffset.X + textureSize.X, textureOffset.Y),
                                textureOffset + textureSize,
                                new Vector2(textureOffset.X, textureOffset.Y + textureSize.X)
                            };

                            int rotation = -blockDefinition.GetSouthTextureRotation(_manager, x, y, z);

                            int localOffset = vertices.Count;
                            vertices.Add(new VertexPositionNormalTexture(new Vector3(x + 0, y + 1, z + 0), new Vector3(0, 1, 0), points[(6 + rotation) % 4]));
                            vertices.Add(new VertexPositionNormalTexture(new Vector3(x + 1, y + 1, z + 0), new Vector3(0, 1, 0), points[(7 + rotation) % 4]));
                            vertices.Add(new VertexPositionNormalTexture(new Vector3(x + 0, y + 1, z + 1), new Vector3(0, 1, 0), points[(5 + rotation) % 4]));
                            vertices.Add(new VertexPositionNormalTexture(new Vector3(x + 1, y + 1, z + 1), new Vector3(0, 1, 0), points[(4 + rotation) % 4]));
                            index.Add(localOffset + 0);
                            index.Add(localOffset + 1);
                            index.Add(localOffset + 3);
                            index.Add(localOffset + 0);
                            index.Add(localOffset + 3);
                            index.Add(localOffset + 2);
                        }

                        ushort           northBlock          = _manager.GetBlock((ChunkPosition.Value * Chunk.CHUNKSIZE) + new Index3(x, y - 1, z));
                        IBlockDefinition northBlockDefintion = DefinitionManager.GetBlockDefinitionByIndex(northBlock);

                        // North
                        if (northBlock == 0 || (!northBlockDefintion.IsSouthSolidWall(_manager, x, y - 1, z) && northBlock != block))
                        {
                            textureOffset = new Vector2(
                                (((textureIndex + blockDefinition.GetNorthTextureIndex(_manager, x, y, z)) % textureColumns) * textureWidth) + 0.002f,
                                (((textureIndex + blockDefinition.GetNorthTextureIndex(_manager, x, y, z)) / textureColumns) * textureWidth) + 0.002f);

                            Vector2[] points = new[] {
                                textureOffset,
                                new Vector2(textureOffset.X + textureSize.X, textureOffset.Y),
                                textureOffset + textureSize,
                                new Vector2(textureOffset.X, textureOffset.Y + textureSize.X)
                            };
                            int rotation = -blockDefinition.GetNorthTextureRotation(_manager, x, y, z);

                            int localOffset = vertices.Count;
                            vertices.Add(new VertexPositionNormalTexture(new Vector3(x + 0, y + 0, z + 1), new Vector3(0, -1, 0), points[(4 + rotation) % 4]));
                            vertices.Add(new VertexPositionNormalTexture(new Vector3(x + 1, y + 0, z + 1), new Vector3(0, -1, 0), points[(5 + rotation) % 4]));
                            vertices.Add(new VertexPositionNormalTexture(new Vector3(x + 0, y + 0, z + 0), new Vector3(0, -1, 0), points[(7 + rotation) % 4]));
                            vertices.Add(new VertexPositionNormalTexture(new Vector3(x + 1, y + 0, z + 0), new Vector3(0, -1, 0), points[(6 + rotation) % 4]));
                            index.Add(localOffset + 0);
                            index.Add(localOffset + 1);
                            index.Add(localOffset + 3);
                            index.Add(localOffset + 0);
                            index.Add(localOffset + 3);
                            index.Add(localOffset + 2);
                        }

                        ushort           westBlock          = _manager.GetBlock((ChunkPosition.Value * Chunk.CHUNKSIZE) + new Index3(x - 1, y, z));
                        IBlockDefinition westBlockDefintion = DefinitionManager.GetBlockDefinitionByIndex(westBlock);

                        // West
                        if (westBlock == 0 || (!westBlockDefintion.IsEastSolidWall(_manager, x - 1, y, z) && westBlock != block))
                        {
                            textureOffset = new Vector2(
                                (((textureIndex + blockDefinition.GetWestTextureIndex(_manager, x, y, z)) % textureColumns) * textureWidth) + 0.002f,
                                (((textureIndex + blockDefinition.GetWestTextureIndex(_manager, x, y, z)) / textureColumns) * textureWidth) + 0.002f);

                            Vector2[] points = new[] {
                                textureOffset,
                                new Vector2(textureOffset.X + textureSize.X, textureOffset.Y),
                                textureOffset + textureSize,
                                new Vector2(textureOffset.X, textureOffset.Y + textureSize.X)
                            };
                            int rotation = -blockDefinition.GetWestTextureRotation(_manager, x, y, z);

                            int localOffset = vertices.Count;
                            vertices.Add(new VertexPositionNormalTexture(new Vector3(x + 0, y + 1, z + 0), new Vector3(-1, 0, 0), points[(7 + rotation) % 4]));
                            vertices.Add(new VertexPositionNormalTexture(new Vector3(x + 0, y + 1, z + 1), new Vector3(-1, 0, 0), points[(4 + rotation) % 4]));
                            vertices.Add(new VertexPositionNormalTexture(new Vector3(x + 0, y + 0, z + 0), new Vector3(-1, 0, 0), points[(6 + rotation) % 4]));
                            vertices.Add(new VertexPositionNormalTexture(new Vector3(x + 0, y + 0, z + 1), new Vector3(-1, 0, 0), points[(5 + rotation) % 4]));
                            index.Add(localOffset + 0);
                            index.Add(localOffset + 1);
                            index.Add(localOffset + 3);
                            index.Add(localOffset + 0);
                            index.Add(localOffset + 3);
                            index.Add(localOffset + 2);
                        }

                        ushort           eastBlock          = _manager.GetBlock((ChunkPosition.Value * Chunk.CHUNKSIZE) + new Index3(x + 1, y, z));
                        IBlockDefinition eastBlockDefintion = DefinitionManager.GetBlockDefinitionByIndex(eastBlock);

                        // Ost
                        if (eastBlock == 0 || (!eastBlockDefintion.IsWestSolidWall(_manager, x + 1, y, z) && eastBlock != block))
                        {
                            textureOffset = new Vector2(
                                (((textureIndex + blockDefinition.GetEastTextureIndex(_manager, x, y, z)) % textureColumns) * textureWidth) + 0.002f,
                                (((textureIndex + blockDefinition.GetEastTextureIndex(_manager, x, y, z)) / textureColumns) * textureWidth) + 0.002f);

                            Vector2[] points = new[] {
                                textureOffset,
                                new Vector2(textureOffset.X + textureSize.X, textureOffset.Y),
                                textureOffset + textureSize,
                                new Vector2(textureOffset.X, textureOffset.Y + textureSize.X)
                            };

                            int rotation = -blockDefinition.GetEastTextureRotation(_manager, x, y, z);

                            int localOffset = vertices.Count;
                            vertices.Add(new VertexPositionNormalTexture(new Vector3(x + 1, y + 1, z + 1), new Vector3(1, 0, 0), points[(5 + rotation) % 4]));
                            vertices.Add(new VertexPositionNormalTexture(new Vector3(x + 1, y + 1, z + 0), new Vector3(1, 0, 0), points[(6 + rotation) % 4]));
                            vertices.Add(new VertexPositionNormalTexture(new Vector3(x + 1, y + 0, z + 1), new Vector3(1, 0, 0), points[(4 + rotation) % 4]));
                            vertices.Add(new VertexPositionNormalTexture(new Vector3(x + 1, y + 0, z + 0), new Vector3(1, 0, 0), points[(7 + rotation) % 4]));
                            index.Add(localOffset + 0);
                            index.Add(localOffset + 1);
                            index.Add(localOffset + 3);
                            index.Add(localOffset + 0);
                            index.Add(localOffset + 3);
                            index.Add(localOffset + 2);
                        }
                    }
                }
            }

            vertexCount = vertices.Count;
            indexCount  = index.Count;

            VertexBuffer vb2 = null;
            IndexBuffer  ib2 = null;

            if (vertexCount > 0)
            {
                try
                {
                    vb2 = new VertexBuffer(graphicsDevice, VertexPositionNormalTexture.VertexDeclaration, vertexCount, BufferUsage.WriteOnly);
                    vb2.SetData <VertexPositionNormalTexture>(vertices.ToArray());

                    ib2 = new IndexBuffer(graphicsDevice, IndexElementSize.ThirtyTwoBits, indexCount, BufferUsage.WriteOnly);
                    ib2.SetData <int>(index.ToArray());
                }
                catch (Exception) { }
            }

            VertexBuffer vbOld = vb;
            IndexBuffer  ibOld = ib;

            lock (this)
            {
                vb     = vb2;
                ib     = ib2;
                loaded = true;
            }

            if (vbOld != null)
            {
                vbOld.Dispose();
            }

            if (ibOld != null)
            {
                ibOld.Dispose();
            }

            lastReset = chunk.ChangeCounter;
        }