loadMtl function

Future<Map<String, Material>> loadMtl(String fileName, { bool isAsset = true, })

Loading material from Material Library File (.mtl). Reference：http://paulbourke.net/dataformats/mtl/

Implementation

Future<Map<String, Material>> loadMtl(String fileName, {bool isAsset = true}) async {
  final materials = <String, Material>{};
  String data;
  try {
    if (isAsset) {
      data = await rootBundle.loadString(fileName);
    } else {
      data = await File(fileName).readAsString();
    }
  } catch (_) {
    return materials;
  }
  final List<String> lines = data.split('\n');

  Material material = Material();
  for (String line in lines) {
    List<String> parts = line.trim().split(RegExp(r"\s+"));
    switch (parts[0]) {
      case 'newmtl':
        material = Material();
        if (parts.length >= 2) {
          material.name = parts[1];
          materials[material.name] = material;
        }
        break;
      case 'Ka':
        if (parts.length >= 4) {
          final v = Vector3(double.parse(parts[1]), double.parse(parts[2]), double.parse(parts[3]));
          material.ambient = v;
        }
        break;
      case 'Kd':
        if (parts.length >= 4) {
          final v = Vector3(double.parse(parts[1]), double.parse(parts[2]), double.parse(parts[3]));
          material.diffuse = v;
        }
        break;
      case 'Ks':
        if (parts.length >= 4) {
          final v = Vector3(double.parse(parts[1]), double.parse(parts[2]), double.parse(parts[3]));
          material.specular = v;
        }
        break;
      case 'Ke':
        if (parts.length >= 4) {
          final v = Vector3(double.parse(parts[1]), double.parse(parts[2]), double.parse(parts[3]));
          material.ke = v;
        }
        break;
      case 'map_Ka':
        if (parts.length >= 2) {
          material.mapKa = parts.last;
        }
        break;
      case 'map_Kd':
        if (parts.length >= 2) {
          material.mapKd = parts.last;
        }
        break;
      case 'Ns':
        if (parts.length >= 2) {
          material.shininess = double.parse(parts[1]);
        }
        break;
      case 'Ni':
        if (parts.length >= 2) {
          material.ni = double.parse(parts[1]);
        }
        break;
      case 'd':
        if (parts.length >= 2) {
          material.opacity = double.parse(parts[1]);
        }
        break;
      case 'illum':
        if (parts.length >= 2) {
          material.illum = int.parse(parts[1]);
        }
        break;
      default:
    }
  }
  return materials;
}