/// <summary>
/// Finds the face to which the given point belongs.
/// </summary>
/// <param name="point">The point to use when searching for the corresponding face.</param>
/// <returns>The face to which the given point belongs.</returns>
/// <remarks><para>Typically, the point will be on or close to the surface of the manifold,
/// such that it is clear that it belongs to a particular face. It does not need to be near
/// the surface, however, as each face implicitly defines a volume above and below it, and
/// all points within that volume belong to that face.</para>
/// <para>Depending on the shape of the manifold, not all faces returned by this method will
/// be internal faces. For example, a rectangular manifold with no wrap-around edges contains
/// a single external face that represents all areas outside the rectangle, and any point that
/// lies on, above, or below this outer area will map to the external face. However, an empty
/// face is guaranteed to never be returned by this method; every point is mappable to some
/// face in the manifold, no matter the shape or topology of the manifold.</para></remarks>
public Topology.Face FindFace(Vector3 point)
{
var partitionIndex = 0;
while (true)
{
var partition = _partitionBinaryTree[partitionIndex];
if (partition.IsOver(point))
{
if (partition._overPartitionIndex != 0)
{
partitionIndex = partition._overPartitionIndex;
}
else
{
var edge = _topology.faceEdges[partition._overEdgeIndex];
if ((edge.wrap & EdgeWrap.FaceToFace) == EdgeWrap.None || edge.isBoundary)
{
return(_topology.faceEdges[partition._overEdgeIndex].face);
}
else
{
point = _surface.ReverseOffsetFaceToFaceAttribute(point, edge.wrap);
partitionIndex = 0;
}
}
}
else
{
if (partition._underPartitionIndex != 0)
{
partitionIndex = partition._underPartitionIndex;
}
else
{
return(_topology.faceEdges[partition._underEdgeIndex].face);
}
}
}
}
/// <summary>
/// Lookup the attribute value for the face of the edge indicated, wrapping according to the attribute's surface if necessary.
/// </summary>
/// <param name="e">The edge whose face's attribute value is desired.</param>
/// <returns>The attribute value for the far face of the edge indicated, relative to the edge's near face.</returns>
/// <remarks><para>To get the raw value unwrapped, see <see cref="P:MakeIt.Tile.FaceArrayAttribute`1.Item(MakeIt.Tile.Topology.Face)"/></para></remarks>
public override Vector3 this[Topology.FaceEdge e]
{
get { return(surface.OffsetFaceToFaceAttribute(array[e.face.index], e.wrap)); }
set { array[e.face.index] = surface.ReverseOffsetFaceToFaceAttribute(array[e.face.index], e.wrap); }
}
