public static async Task <ObjMesh> Load(string definition)
{
var that = new ObjMesh();
var lines = definition
.Split('\n')
.Where(l => l.Length > 0 && l[0] != '#')
.Select(l => l.Split(' '));
foreach (var line in lines)
{
await AsyncExtensions.WaitMoment();
var lineType = line[0];
switch (lineType)
{
case "mtllib": // material library: mtllib joint.mtl
// ignore
break;
case "o": // object: o Cylinder006
// ignore
break;
case "v": // geometric vertex: v 3.2e-3 -1.4e-10 -5.8e-2
that.GeometryVertices.Add(Parse3DCoords(line));
break;
case "vt": // texture vertex: vt 0.2 0.7
that.TextureVertices.Add(ParseUvCoords(line));
break;
case "vn": // vertex normal: vn 0.9 -5.3e-9 -6.3e-2
that.VertexNormals.Add(Parse3DCoords(line));
break;
case "g": // group name: g Cylinder006_CA_MISC
// ignore
break;
case "usemtl": // material name: usemtl CA_MISC
// ignore for now
break;
case "s": // smoothing group: s 1
// ignore for now
break;
case "f": // face: f 18/9/26 25/7/61 17/5/19
// entry: geometric vertex id / texture vertex id / vertex normal id
var indices = line
.Skip(1)
.SelectMany(entry => entry.Split('/'))
.Select(s => s.Length > 0 ? (int.Parse(s) - 1) : (int?)null)
.ToArray();
Debug.Assert(indices.Length == 9);
that.VertexComponentIds.AddRange(indices);
break;
default:
throw new ArgumentException($"unsupported obj format entry: {line}", nameof(definition));
}
}
Debug.Assert(that.VertexComponentIds.Count % 9 == 0); // three vertices for geometry, tex and normals
return(that);
}