Function DecodeReader

loader/obj/obj.go:131–215

DecodeReader decodes the specified obj and mtl readers returning a decoder object and an error if a problem was encoutered while parsing the OBJ. Pass a valid io.Reader to override the materials defined in the OBJ file, or `nil` to use the materials listed in the OBJ's "mtllib" line (if present), a

(objreader, mtlreader io.Reader)

// material as a last resort. No error will be returned for problems
// with materials--a gray default material will be used if nothing else works.
func DecodeReader(objreader, mtlreader io.Reader) (*Decoder, error) {

	dec := new(Decoder)
	dec.Objects = make([]Object, 0)
	dec.Warnings = make([]string, 0)
	dec.Materials = make(map[string]*Material)
	dec.Vertices = math32.NewArrayF32(0, 0)
	dec.Normals = math32.NewArrayF32(0, 0)
	dec.Uvs = math32.NewArrayF32(0, 0)
	dec.line = 1

	// Parses obj lines
	err := dec.parse(objreader, dec.parseObjLine)
	if err != nil {
		return nil, err
	}

	// Parses mtl lines
	// 1) try passed in mtlreader,
	// 2) try file in mtllib line
	// 3) try <obj_filename>.mtl
	// 4) use default material as last resort
	dec.matCurrent = nil
	dec.line = 1
	// first try: use the material file passed in as an io.Reader
	err = dec.parse(mtlreader, dec.parseMtlLine)
	if err != nil {

		// 2) if mtlreader produces an error (eg. it's nil), try the file listed
		// in the OBJ's matlib line, if it exists.
		if dec.Matlib != "" {
			// ... first need to get the path of the OBJ, since mtllib is relative
			var mtllibPath string
			if objf, ok := objreader.(*os.File); ok {
				// NOTE (quillaja): this is a hack because we need the directory of
				// the OBJ, but can't get it any other way (dec.mtlDir isn't set
				// until AFTER this function is finished).
				objdir := filepath.Dir(objf.Name())
				mtllibPath = filepath.Join(objdir, dec.Matlib)
				dec.mtlDir = objdir // NOTE (quillaja): should this be set?
			}
			mtlf, errMTL := os.Open(mtllibPath)
			defer mtlf.Close()
			if errMTL == nil {
				err = dec.parse(mtlf, dec.parseMtlLine) // will set err to nil if successful
			}
		}

		// 3) if the mtllib line fails try <obj_filename>.mtl in the same directory.
		// process is basically identical to the above code block.
		if err != nil {
			var mtlpath string
			if objf, ok := objreader.(*os.File); ok {
				objdir := strings.TrimSuffix(objf.Name(), ".obj")
				mtlpath = objdir + ".mtl"
				dec.mtlDir = objdir // NOTE (quillaja): should this be set?
			}
			mtlf, errMTL := os.Open(mtlpath)