/// <summary>
 /// Decompresses vertex data in-place.
 /// </summary>
 /// <param name="vertices">The vertices to decompress in-place.</param>
 /// <param name="compressor">The compressor to use.</param>
 private static void DecompressVertices(IEnumerable<ObjVertex> vertices, VertexCompressor compressor)
 {
     foreach (var vertex in vertices)
     {
         vertex.Position = compressor.DecompressPosition(vertex.Position);
         vertex.TexCoords = compressor.DecompressUv(vertex.TexCoords);
     }
 }
        /// <summary>
        /// Writes mesh data to the .obj.
        /// </summary>
        /// <param name="reader">The mesh reader to use.</param>
        /// <param name="compressor">The vertex compressor to use.</param>
        /// <param name="resourceStream">A stream open on the resource data.</param>
        public void ExtractMesh(MeshReader reader, VertexCompressor compressor, Stream resourceStream)
        {
            // Read the vertex buffer and decompress each vertex
            var vertices = ReadVertices(reader, resourceStream);
            DecompressVertices(vertices, compressor);

            // Write out the vertices
            WriteVertices(vertices);

            // Read and write out the triangles for each part
            foreach (var part in reader.Mesh.Parts)
            {
                var indexes = ReadIndexes(reader, part, resourceStream);
                WriteTriangles(indexes);
            }
            _baseIndex += (uint)vertices.Count;
        }
        public override bool Execute(List<string> args)
        {
            if (args.Count != 3)
                return false;
            var variantName = args[0];
            var fileType = args[1];
            var fileName = args[2];
            if (fileType != "obj")
                return false;

            // Find the variant to extract
            if (_model.RenderModel == null)
            {
                Console.Error.WriteLine("The model does not have a render model associated with it.");
                return true;
            }
            var variant = _model.Variants.FirstOrDefault(v => (_stringIds.GetString(v.Name) ?? v.Name.ToString()) == variantName);
            if (variant == null && _model.Variants.Count > 0)
            {
                Console.Error.WriteLine("Unable to find variant \"{0}\"", variantName);
                Console.Error.WriteLine("Use \"listvariants\" to list available variants.");
                return true;
            }

            // Load resource caches
            Console.WriteLine("Loading resource caches...");
            var resourceManager = new ResourceDataManager();
            try
            {
                resourceManager.LoadCachesFromDirectory(_fileInfo.DirectoryName);
            }
            catch
            {
                Console.WriteLine("Unable to load the resource .dat files.");
                Console.WriteLine("Make sure that they all exist and are valid.");
                return true;
            }

            // Deserialize the render model tag
            Console.WriteLine("Reading model data...");
            RenderModel renderModel;
            using (var cacheStream = _fileInfo.OpenRead())
            {
                var renderModelContext = new TagSerializationContext(cacheStream, _cache, _model.RenderModel);
                renderModel = TagDeserializer.Deserialize<RenderModel>(renderModelContext);
            }
            if (renderModel.Resource == null)
            {
                Console.Error.WriteLine("Render model does not have a resource associated with it");
                return true;
            }

            // Deserialize the resource definition
            var resourceContext = new ResourceSerializationContext(renderModel.Resource);
            var definition = TagDeserializer.Deserialize<RenderGeometryResourceDefinition>(resourceContext);

            using (var resourceStream = new MemoryStream())
            {
                // Extract the resource data
                resourceManager.Extract(renderModel.Resource, resourceStream);
                using (var objFile = new StreamWriter(File.Open(fileName, FileMode.Create, FileAccess.Write)))
                {
                    var objExtractor = new ObjExtractor(objFile);
                    var vertexCompressor = new VertexCompressor(renderModel.Compression[0]); // Create a (de)compressor from the first compression block
                    if (variant != null)
                    {
                        // Extract each region in the variant
                        foreach (var region in variant.Regions)
                        {
                            // Get the corresonding region in the render model tag
                            if (region.RenderModelRegionIndex >= renderModel.Regions.Count)
                                continue;
                            var renderModelRegion = renderModel.Regions[region.RenderModelRegionIndex];

                            // Get the corresponding permutation in the render model tag
                            // (Just extract the first permutation for now)
                            if (region.Permutations.Count == 0)
                                continue;
                            var permutation = region.Permutations[0];
                            if (permutation.RenderModelPermutationIndex >= renderModelRegion.Permutations.Count)
                                continue;
                            var renderModelPermutation = renderModelRegion.Permutations[permutation.RenderModelPermutationIndex];

                            // Extract each mesh in the permutation
                            var meshIndex = renderModelPermutation.MeshIndex;
                            var meshCount = renderModelPermutation.MeshCount;
                            var regionName = _stringIds.GetString(region.Name) ?? region.Name.ToString();
                            var permutationName = _stringIds.GetString(permutation.Name) ?? permutation.Name.ToString();
                            Console.WriteLine("Extracting {0} mesh(es) for {1}:{2}...", meshCount, regionName, permutationName);
                            for (var i = 0; i < meshCount; i++)
                            {
                                // Create a MeshReader for the mesh and pass it to the obj extractor
                                var meshReader = new MeshReader(renderModel.Meshes[meshIndex + i], definition);
                                objExtractor.ExtractMesh(meshReader, vertexCompressor, resourceStream);
                            }
                        }
                    }
                    else
                    {
                        // No variant - just extract every mesh
                        Console.WriteLine("Extracting {0} mesh(es)...", renderModel.Meshes.Count);
                        foreach (var mesh in renderModel.Meshes)
                        {
                            // Create a MeshReader for the mesh and pass it to the obj extractor
                            var meshReader = new MeshReader(mesh, definition);
                            objExtractor.ExtractMesh(meshReader, vertexCompressor, resourceStream);
                        }
                    }
                    objExtractor.Finish();
                }
            }
            Console.WriteLine("Done!");
            return true;
        }