public static IReadOnlyCollection <int> GetTriangles <TVertex>(
this IDivisibleMesh <TVertex> mesh, VertexWindingOrder winding)
where TVertex : struct
{
Contracts.Requires.That(mesh != null);
Contracts.Requires.That(winding.IsValidEnumValue());
return(new ReadOnlyCollection <int>(mesh.EnumerateTriangles(winding), mesh.Offsets.Count));
}
public static void CopyIn <TVertex>(
IMeshDataTransfer <TVertex> instance, IDivisibleMesh <TVertex> mesh, VertexWindingOrder winding)
where TVertex : struct
{
Contracts.Requires.That(instance != null);
Contracts.Requires.That(mesh != null);
Contracts.Requires.That(
mesh.Vertices.Count <= instance.MaxVertices || instance.MaxVertices == Capacity.Unbounded);
Contracts.Requires.That(winding.IsValidEnumValue());
DivisibleMesh.VerifyContracts(mesh);
}
public static IEnumerable <int> EnumerateTriangles <TVertex>(
this IDivisibleMesh <TVertex> mesh, VertexWindingOrder winding)
where TVertex : struct
{
Contracts.Requires.That(mesh != null);
Contracts.Requires.That(winding.IsValidEnumValue());
var offsets = mesh.Offsets.GetEnumerator();
int globalOffset = 0;
switch (winding)
{
case VertexWindingOrder.Clockwise:
foreach (var group in mesh.Groups)
{
for (int count = 0; count < group.Offsets; count++)
{
var success = offsets.MoveNext();
Contracts.Assert.That(success);
yield return(globalOffset + offsets.Current);
}
globalOffset += group.Vertices;
}
yield break;
case VertexWindingOrder.Counterclockwise:
foreach (var group in mesh.Groups)
{
// IDivisibleMesh<TVertex> is always stored in clockwise winding order
// so the last 2 offsets of each triangle need to be swapped to become counterclockwise
for (int count = 0; count < group.Triangles; count++)
{
// return the first offset as normal
var success = offsets.MoveNext();
Contracts.Assert.That(success);
yield return(globalOffset + offsets.Current);
// temporarily store the second offset
success = offsets.MoveNext();
Contracts.Assert.That(success);
var tempOffset = offsets.Current;
// return the third offset as though it were the second offset
success = offsets.MoveNext();
Contracts.Assert.That(success);
yield return(globalOffset + offsets.Current);
// return the second offset (stored) as though it were the third offset
yield return(globalOffset + tempOffset);
}
globalOffset += group.Vertices;
}
yield break;
default: throw InvalidEnumArgument.CreateException(nameof(winding), winding);
}
}