public static Vector CalculateNormal(IModel model, Face f)
{
var normal = new Vector(0, 0, 0);
for (var idx0 = 0; idx0 < f.VertexIndices.Length; idx0++)
{
var idx1 = new CircularIterator(f.VertexIndices.Length, idx0 + 1).Current;
var idx2 = new CircularIterator(f.VertexIndices.Length, idx1 + 1).Current;
normal = normal + CalculateNormal(model, f.VertexIndices[idx0], f.VertexIndices[idx1], f.VertexIndices[idx2]);
}
return(normal.Normalize());
}
private static bool CanClip(IModel model, Face f, IList <int> vertices, int i0, int i1, int i2)
{
if (IsConcave(model, f, vertices[i0], vertices[i1], vertices[i2]))
{
return(false);
}
var ip = new CircularIterator(vertices.Count, i2 + 1);
do
{
if (!IsOutSideTriangle(model, f, vertices[i0], vertices[i1], vertices[i2], vertices[ip.Current]))
{
return(false);
}
ip.MoveNext();
} while (ip.Current != i0);
return(true);
}
private static List <int[]> Triangulate(IModel model, Face f, List <int> vertices, List <int[]> results, int startIndex = 0)
{
var i0 = new CircularIterator(vertices.Count, startIndex).Current;
var i1 = new CircularIterator(vertices.Count, startIndex + 1).Current;
var i2 = new CircularIterator(vertices.Count, startIndex + 2).Current;
if (vertices.Count == 3)
{
results.Add(vertices.ToArray());
return(results);
}
if (!CanClip(model, f, vertices, i0, i1, i2))
{
return(Triangulate(model, f, vertices, results, i1));
}
results.Add(new[] { vertices[i0], vertices[i1], vertices[i2] });
Debug.Assert(vertices.Remove(vertices[i1]));
Triangulate(model, f, vertices, results, i2);
return(results);
}