ExtractSbspObj.cs

            var resourceContext = new ResourceSerializationContext(sbsp.Resource2);
            var definition = _info.Deserializer.Deserialize<RenderGeometryResourceDefinition>(resourceContext);
            var resourceStream = new MemoryStream();
            resourceManager.Extract(sbsp.Resource2, resourceStream);

            using (var objFile = new StreamWriter(File.Open("D:\\Halo\\bsp_test.obj", FileMode.Create, FileAccess.Write)))
            {
                var objExtractor = new ObjExtractor(objFile);
                
                for (var i = 0; i < sbsp.Sections2.Count; i++)
                {
                    var section = sbsp.Sections2[i];

                    var meshReader = new MeshReader(_info.Version, section, definition);

                    CompressionInfo compression = new CompressionInfo();

                    if (i < sbsp.Compression2.Count)
                        compression = sbsp.Compression2[i];

                    var vertexCompressor = new VertexCompressor(compression);
                    objExtractor.ExtractMesh(meshReader, vertexCompressor, resourceStream);
                }

                objExtractor.Finish();
            }

use this after deserializing an sbsp tag in tag tool to extract an sbsp's geometry resources to an .obj file.