internal static void CollapseEdge(this Kernel kernel, HalfEdge edge)
{
if (EdgeLinker.IsDummyPairEdge(edge))
{
edge = edge.Pair;
}
// if the edge is naked, we don't have to change the other face
if (EdgeLinker.IsDummyPairEdge(edge.Pair))
{
CollapseNakedEdge(edge, kernel);
return;
}
CollapseEdgeBetweenFaces(edge, kernel);
}
/// <summary>
/// Removes all unused Edges from the kernel
/// Unused edges are edge-pairs, where both pairs are naked
/// </summary>
/// <param name="kernel"></param>
internal static void RemoveUnusedEdges(this Kernel kernel)
{
foreach (var edge in kernel.Edges)
{
if (!EdgeLinker.IsDummyPairEdge(edge))
{
continue;
}
if (!EdgeLinker.IsDummyPairEdge(edge.Pair))
{
continue;
}
kernel.Remove(edge);
}
}
/// <summary>
/// Removes a <see cref="HalfEdge"/>. This also removes its pair,
/// as HalfEdges are not allowed to be single ;)
/// </summary>
/// <param name="edge"></param>
/// <returns></returns>
public override bool Remove(HalfEdge edge)
{
// handle active references to edge
if (!EdgeLinker.IsDummyPairEdge(edge))
{
RemoveReferences(edge);
}
// handle active references to its pair
if (!EdgeLinker.IsDummyPairEdge(edge.Pair))
{
RemoveReferences(edge.Pair);
}
// unlink the edges
EdgeLinker.UnlinkEdge(edge);
EdgeLinker.UnlinkEdge(edge.Pair);
// remove edges from inner collection
_elements.Remove(edge);
_elements.Remove(edge.Pair);
return(true);
}
internal static bool TrySplitEdge(this Kernel kernel, HalfEdge edge, double t, out (HalfEdge, HalfEdge) parts)
{
parts = (null, null);
// TODO: Error checks
if (EdgeLinker.IsDummyPairEdge(edge))
{
edge = edge.Pair;
}
// test valid param
if (0 > t || t > 1)
{
return(false);
}
// calculate vec at param
var vec = edge.Origin.Position.VecAtParameter(edge.Target.Position, t);
// convert to a vertex
var vertex = kernel.GetVertexForPosition(vec);
// store edge pair, and conditionals
var pair = edge.Pair;
var isDummy = EdgeLinker.IsDummyPairEdge(pair);
var isStart = edge.Face.Start == edge;
// create new edges
var firstHalf = new HalfEdge
{
Face = edge.Face,
Previous = edge.Previous,
Origin = edge.Origin
};
var secondHalf = new HalfEdge
{
Face = edge.Face,
Next = edge.Next,
Origin = vertex
};
var pairFirstHalf = new HalfEdge
{
Face = pair.Face,
Previous = pair.Previous,
Origin = pair.Origin,
Pair = secondHalf,
};
var pairSecondHalf = new HalfEdge
{
Face = pair.Face,
Next = pair.Next,
Origin = vertex,
Pair = firstHalf
};
// link halves
firstHalf.Next = secondHalf;
pairFirstHalf.Next = pairSecondHalf;
// remove original edges
kernel.Remove(edge);
// add new halves
if (!isDummy)
{
kernel.Insert(firstHalf);
kernel.Insert(secondHalf);
kernel.Insert(pairFirstHalf);
kernel.Insert(pairSecondHalf);
}
else
{
firstHalf.Pair = null;
secondHalf.Pair = null;
kernel.Insert(firstHalf);
kernel.Insert(secondHalf);
}
// set start to first half
if (isStart)
{
firstHalf.Face.Start = firstHalf;
}
parts = (firstHalf, secondHalf);
return(true);
}
