/// <summary>
/// Parses one object from input .obj file.
/// </summary>
/// <param name="reader">Reader with current position in .obj file.</param>
/// <returns>
/// Triangle mesh with name of the associated material.
/// If material name is an empty string, no material was used.
/// </returns>
private Tuple <string, FastTriangleMesh> parseObject(StreamReader reader, ref int verticesCount, ref int txtCoordsCount, ref int normalsCount)
{
SceneBrep scene = new SceneBrep();
string materialName = "";
int v0 = scene.Vertices;
int lastVertex = v0 - 1;
int faces = 0;
List <Vector2> txtCoords = new List <Vector2>(256);
List <Vector3> normals = new List <Vector3>(256);
int lastTxtCoord = -1;
int lastNormal = -1;
int[] f = new int[3];
while (!reader.EndOfStream)
{
// Check if there is defined "o" tag, if yes, it is the end of definition of one object
// and return this object.
if ((char)reader.Peek() == 'o')
{
break;
}
string line = reader.ReadLine();
string[] tokens = line.Split();
if (tokens.Length == 0)
{
continue;
}
switch (tokens[0])
{
case "v":
if (tokens.Length != 4)
{
throw new Exception("Incorrect .obj file.");
}
// Add vertex.
float x, y, z;
if (!float.TryParse(tokens[1], NumberStyles.Float, CultureInfo.InvariantCulture, out x) ||
!float.TryParse(tokens[2], NumberStyles.Float, CultureInfo.InvariantCulture, out y) ||
!float.TryParse(tokens[3], NumberStyles.Float, CultureInfo.InvariantCulture, out z))
{
throw new Exception("Incorrect .obj file.");
}
lastVertex = scene.AddVertex(new Vector3(x, y, z));
break;
case "vt":
if (tokens.Length != 3)
{
throw new Exception("Incorrect .obj file.");
}
// Add vertex.
float u, v;
if (!float.TryParse(tokens[1], NumberStyles.Float, CultureInfo.InvariantCulture, out u) ||
!float.TryParse(tokens[2], NumberStyles.Float, CultureInfo.InvariantCulture, out v))
{
throw new Exception("Incorrect .obj file.");
}
txtCoords.Add(new Vector2(u, v));
++lastTxtCoord;
break;
case "vn":
if (tokens.Length != 4)
{
throw new Exception("Incorrect .obj file.");
}
// Add vertex.
float nx, ny, nz;
if (!float.TryParse(tokens[1], NumberStyles.Float, CultureInfo.InvariantCulture, out nx) ||
!float.TryParse(tokens[2], NumberStyles.Float, CultureInfo.InvariantCulture, out ny) ||
!float.TryParse(tokens[3], NumberStyles.Float, CultureInfo.InvariantCulture, out nz))
{
throw new Exception("Incorrect .obj file.");
}
normals.Add(new Vector3(nx, ny, nz));
break;
case "usemtl":
// Set name of the material used for this object.
if (tokens.Length != 2)
{
throw new Exception("Incorrect .obj file.");
}
materialName = tokens[1];
break;
case "f":
// Face must be formed by at least three vertices.
if (tokens.Length < 4)
{
continue;
}
// Number of vertices.
int N = tokens.Length - 1;
// Reuse same array for each face and resize it if needed.
if (f.Length < N)
{
f = new int[N];
}
// Shrink it if less vertices is used.
if (N < f.Length)
{
f = new int[N];
}
int i;
for (i = 0; i < N; i++) // read indices for one vertex
{
string[] vt = tokens[i + 1].Split('/');
int ti, ni;
ti = ni = 0; // 0 => value not present
// 0 .. vertex coord index
if (!int.TryParse(vt[0], out f[i]) ||
f[i] == 0)
{
break;
}
if (f[i] > 0)
{
f[i] = v0 + f[i] - 1 - verticesCount;
}
else
{
f[i] = lastVertex + 1 - f[i];
}
if (vt.Length > 1)
{
// 1 .. texture coord index (not yet)
if (!int.TryParse(vt[1], out ti))
{
ti = 0;
}
if (vt.Length > 2)
{
// 2 .. normal vector index
if (!int.TryParse(vt[2], out ni))
{
ni = 0;
}
}
}
// there was a texture coord..
if (ti != 0)
{
if (ti > 0)
{
ti = ti - txtCoordsCount - 1;
}
else
{
ti = lastTxtCoord + 1 - ti;
}
if (ti >= 0 && ti < txtCoords.Count)
{
scene.SetTxtCoord(f[i], txtCoords[ti]);
}
}
// there was a normal..
if (ni != 0)
{
if (ni > 0)
{
ni = ni - normalsCount - 1;
}
else
{
ni = lastNormal + 1 - ni;
}
if (ni >= 0 && ni < normals.Count)
{
scene.SetNormal(f[i], normals[ni]);
}
}
}
N = i;
for (i = 1; i < N - 1; i++)
{
scene.AddTriangle(f[0], f[i], f[i + 1]);
faces++;
}
break;
}
}
// Update count of vertices, txt coords and normals.
verticesCount += scene.Vertices;
txtCoordsCount += txtCoords.Count;
normalsCount += normals.Count;
scene.BuildCornerTable();
scene.BuildBoundingBox();
return(new Tuple <string, FastTriangleMesh>(materialName, new FastTriangleMesh(scene)));
}
