/// <summary>
/// Calculates the normal vector for a given face.
/// </summary>
/// <param name="f">The face to calculate the normal for.</param>
/// <returns>The nomal vector for the face.</returns>
/// <exception cref="System.Exception">The face doesn't consist of 3 or more vertices.</exception>
public double3 CalcFaceNormal(Face f)
{
if (f.InxVert.Length < 3)
throw new FormatException("Cannot calculate normal of degenerate face with only " + f.InxVert.Length + " vertices.");
var vertex0 = f.InxVert[0];
double3 v1 = _vertices[vertex0] - _vertices[f.InxVert[2]];
double3 v2 = _vertices[vertex0] - _vertices[f.InxVert[1]];
return double3.Normalize(double3.Cross(v1, v2));
}
private IEnumerable<ushort> Triangulate(Face f, int[] indices)
{
if (f.InxVert.Length < 3)
return null;
if (indices == null)
indices = f.InxVert;
ushort[] ret = new ushort[3 * (f.InxVert.Length-2)];
// Perform a fan triangulation
for (int i = 2; i < f.InxVert.Length; i++ )
{
ret[(i - 2)*3 + 0] = (ushort)indices[0];
ret[(i - 2)*3 + 1] = (ushort)indices[i - 1];
ret[(i - 2)*3 + 2] = (ushort)indices[i];
}
return ret;
}
/// <summary>
/// Adds the face.
/// </summary>
/// <param name="vertInx">The vert inx.</param>
/// <param name="texCoordInx">The tex coord inx.</param>
/// <param name="normalInx">The normal inx.</param>
/// <returns>The face count as integer value.</returns>
/// <exception cref="System.ArgumentNullException">vertInx</exception>
/// <exception cref="System.ArgumentException">
/// "Vertex index out of range: vertInx[i]"
/// or
/// "Number of texture coordinate indices must match number of vertex indices"
/// or
/// "Texture coordinate index out of range: texCoordInx[i]"
/// or
/// "Number of normal indices must match number of vertex indices"
/// or
/// "Normal index out of range: normalInx[i]"
/// </exception>
public int AddFace(int[] vertInx, int[] texCoordInx, int[] normalInx)
{
int i;
Face f = new Face();
// Plausibility checks interleaved...
if (vertInx == null)
throw new ArgumentNullException("vertInx");
f.InxVert = new int[vertInx.Length];
for(i = 0; i < vertInx.Length; i++)
{
var vInx = vertInx[i];
if (!(0 <= vInx && vInx < _vertices.Count))
throw new ArgumentException("Vertex index out of range: " + vInx, "vertInx[" + i + "]");
f.InxVert[i] = vInx;
}
if (texCoordInx != null)
{
if (texCoordInx.Length != vertInx.Length)
throw new ArgumentException(
"Number of texture coordinate indices must match number of vertex indices", "texCoordInx");
f.InxTexCoord = new int[texCoordInx.Length];
for (i = 0; i < texCoordInx.Length; i++)
{
var tInx = texCoordInx[i];
if (!(0 <= tInx && tInx < _texCoords.Count))
throw new ArgumentException("Texture coordinate index out of range: " + tInx, "texCoordInx[" + i + "]");
f.InxTexCoord[i] = tInx;
}
}
if (normalInx != null)
{
if (normalInx.Length != vertInx.Length)
throw new ArgumentException("Number of normal indices must match number of vertex indices",
"normalInx");
f.InxNormal = new int[normalInx.Length];
for (i = 0; i < normalInx.Length; i++)
{
var nInx = normalInx[i];
if (!(0 <= nInx && nInx < _normals.Count))
throw new ArgumentException("Normal index out of range: " + nInx, "normalInx[" + i + "]");
f.InxNormal[i] = nInx;
}
}
// Actually add the faces
if (_faces == null)
_faces = new List<Face>();
_faces.Add(f);
return _faces.Count - 1;
}
