/// <summary>
/// Sorting function for the entries in the output parameter outList used for
/// function GatherTraceData().
/// </summary>
/// <param name="x">The left item being sorted.</param>
/// <param name="y">The right item being sorted.</param>
/// <returns>The comparison return.</returns>
public static int _LexicalSubdivSort(Utils.BezierSubdivSample x, Utils.BezierSubdivSample y)
{
// We only care about the "a" SubdivSample.
if (x.a.lEst == y.a.lEst)
{
return(0);
}
if (x.a.lEst < y.a.lEst)
{
return(-1);
}
return(1);
}
/// <summary>
/// Perform an intersection operation between two islands using a reflow strategy.
/// </summary>
/// <param name="dst">The destination of where the intersected path will be placed.</param>
/// <param name="islandSegsA">A list of all the nodes in island A.</param>
/// <param name="islandSegsB">A list of all the nodes in island B.</param>
/// <param name="onIslA">If the islands were processed, this output parameter contains a node
/// on the new shape.</param>
/// <returns>The results from the operation.</returns>
/// <remarks>islandSegsA and islandSegsB should only contain elements in the island, and should not
/// be confused with all nodes in the parent loop.</remarks>
public static BoundingMode Intersection(
BLoop dst,
List <BNode> islandSegsA,
List <BNode> islandSegsB,
out BNode onIslA)
{
// For the intersection, if there's ANY geometry return, it's a copy.
// It's expected after this operation that the original islands will
// be destroyed and only the copies will be left.
float leftWinding = BNode.CalculateWinding(islandSegsA[0].Travel());
float rightWinding = BNode.CalculateWinding(islandSegsB[0].Travel());
if (leftWinding > 0.0f != rightWinding > 0.0f)
{
islandSegsB[0].ReverseChainOrder();
}
onIslA = null;
List <Utils.BezierSubdivSample> delCollisions = new List <Utils.BezierSubdivSample>();
GetLoopCollisionInfo(islandSegsA, islandSegsB, delCollisions);
Utils.BezierSubdivSample.CleanIntersectionList(delCollisions);
if (delCollisions.Count == 0)
{
BoundingMode bm = GetLoopBoundingMode(islandSegsA, islandSegsB);
if (bm == BoundingMode.NoCollision)
{
return(BoundingMode.NoCollision);
}
else if (bm == BoundingMode.RightSurroundsLeft)
{
// If the right is fully surrounded, the right is kept.
Dictionary <BNode, BNode> insertCloneMap = BNode.CloneNodes(islandSegsA, false);
foreach (BNode bn in insertCloneMap.Values)
{
onIslA = bn;
bn.SetParent(dst);
}
onIslA = islandSegsA[0];
return(BoundingMode.RightSurroundsLeft);
}
else if (bm == BoundingMode.LeftSurroundsRight)
{
// If the left is fully surrounded, the left is kept.
Dictionary <BNode, BNode> insertCloneMap = BNode.CloneNodes(islandSegsB, false);
foreach (BNode bn in insertCloneMap.Values)
{
onIslA = bn;
bn.SetParent(dst);
}
onIslA = islandSegsA[0];
return(BoundingMode.LeftSurroundsRight);
}
}
// Make copies of both, remap and keep their intersection.
Dictionary <BNode, BNode> cloneMapA = BNode.CloneNodes(islandSegsA, false);
Dictionary <BNode, BNode> cloneMapB = BNode.CloneNodes(islandSegsB, false);
foreach (BNode bn in cloneMapA.Values)
{
bn.SetParent(dst);
}
foreach (BNode bn in cloneMapB.Values)
{
bn.SetParent(dst);
}
for (int i = 0; i < delCollisions.Count; ++i)
{
Utils.BezierSubdivSample bss = delCollisions[i];
bss.a.node = cloneMapA[bss.a.node];
bss.b.node = cloneMapB[bss.b.node];
delCollisions[i] = bss;
}
Dictionary <Utils.NodeTPos, BNode.SubdivideInfo> colSlideInfo = SliceCollisionInfo(delCollisions);
Dictionary <Utils.NodeTPos, BNode> createdSubdivs = new Dictionary <Utils.NodeTPos, BNode>();
SplitCollection splitCol = new SplitCollection(dst, delCollisions, createdSubdivs);
//left.nodes.Clear();
//foreach(BNode bn in islandSegsA)
// bn.SetParent(null, false);
//
////right.DumpInto(dst); // Move everything in from the other loop
foreach (BNode bn in islandSegsB)
{
bn.SetParent(dst, false);
}
HashSet <BNode> looseEnds = new HashSet <BNode>();
foreach (Utils.BezierSubdivSample bss in delCollisions)
{
BNode.SubdivideInfo sdiA = colSlideInfo[bss.GetTPosA()];
BNode.SubdivideInfo sdiB = colSlideInfo[bss.GetTPosB()];
float wind = Utils.Vector2Cross(sdiA.subOut, sdiB.subOut);
BNode colNode = createdSubdivs[bss.GetTPosA()];
onIslA = colNode;
if (wind < 0.0f != leftWinding < 0.0f)
{
BNode nA = splitCol.GetNextTo(bss.GetTPosA());
BNode nB = splitCol.GetPreviousTo(bss.GetTPosB());
nA.TanIn = sdiA.nextIn;
nB.TanOut = sdiB.prevOut;
colNode.UseTanIn = bss.b.node.IsLine() == false;
colNode.UseTanOut = bss.a.node.IsLine() == false;
colNode.TanIn = sdiB.subIn;
colNode.TanOut = sdiA.subOut;
nB.next = colNode;
colNode.prev = nB;
nA.prev = colNode;
colNode.next = nA;
looseEnds.Add(bss.a.node);
looseEnds.Add(splitCol.GetSplitInfo(bss.b.node).origNext);
}
else
{
BNode nA = splitCol.GetPreviousTo(bss.GetTPosA());
BNode nB = splitCol.GetNextTo(bss.GetTPosB());
nA.TanOut = sdiA.prevOut;
nB.TanIn = sdiB.nextIn;
colNode.UseTanIn = bss.a.node.IsLine() == false;
colNode.UseTanOut = bss.b.node.IsLine() == false;
colNode.TanIn = sdiA.subIn;
colNode.TanOut = sdiB.subOut;
nA.next = colNode;
colNode.prev = nA;
nB.prev = colNode;
colNode.next = nB;
looseEnds.Add(splitCol.GetSplitInfo(bss.a.node).origNext);
looseEnds.Add(bss.b.node);
}
}
// Figure out what internal items need to be removed by
// checking which nodes have unmatching connectivity.
ClipLooseEnds(looseEnds);
return(BoundingMode.Collision);
}
/// <summary>
/// Perform a difference operation between two islands using a reflow strategy.
/// </summary>
/// <param name="dstloop">The destination of where the differenced path will be placed.</param>
/// <param name="islandSegsA">A list of all the nodes in island A.</param>
/// <param name="islandSegsB">A list of all the nodes in island B.</param>
/// <param name="onIslA">A node on the resulting path.</param>
/// <param name="processFullOverlaps">If true, check and handle is one of the parameter islands
/// completly wraps around the other island.</param>
/// <returns>The results from the operation.</returns>
/// <remarks>islandSegsA and islandSegsB should only contain elements in the island, and should not
/// be confused with all nodes in the parent loop.</remarks>
public static BoundingMode Difference(BLoop dstloop, List <BNode> islandSegsA, List <BNode> islandSegsB, out BNode onIslA, bool processFullOverlaps)
{
// If there is any interaction, a copy of islandB is made and used - this means
// if islandB should be removed, it is up to the caller to remove it themselves.
//
// This is done because we don't know if the shape being subtracted is part of a
// bigger operation where it's subtracted against multiple islands for multi-island
// loop subtraction, or shape subtraction.
float leftWind = BNode.CalculateWinding(islandSegsA[0].Travel());
float rightWind = BNode.CalculateWinding(islandSegsB[0].Travel());
// They need to have opposite windings.
if (leftWind > 0.0f == rightWind > 0.0f)
{
islandSegsB[0].ReverseChainOrder();
}
List <Utils.BezierSubdivSample> delCollisions = new List <Utils.BezierSubdivSample>();
GetLoopCollisionInfo(islandSegsA, islandSegsB, delCollisions);
Utils.BezierSubdivSample.CleanIntersectionList(delCollisions);
onIslA = null;
// If we have an odd number of collisions, we have a problem because we have
// any entry without an exit which will lead to corrupt topology. For now we
// don't have a way to resolve that, but at least we can exit on 1 without
// causing issues (in theory at least).
if (delCollisions.Count == 1)
{
return(BoundingMode.NoCollision);
}
if (delCollisions.Count == 0)
{
BoundingMode bm = GetLoopBoundingMode(islandSegsA, islandSegsB);
if (processFullOverlaps == false)
{
onIslA = islandSegsA[0];
return(bm);
}
if (bm == BoundingMode.NoCollision)
{
onIslA = islandSegsA[0];
return(BoundingMode.NoCollision);
}
else if (bm == BoundingMode.RightSurroundsLeft)
{
// Everything was subtracted out
foreach (BNode bn in islandSegsA)
{
onIslA = bn;
bn.SetParent(null);
}
return(BoundingMode.RightSurroundsLeft);
}
else if (bm == BoundingMode.LeftSurroundsRight)
{
// Leave the reverse winding inside as a hollow cavity - and
// nothing needs to be changed.
Dictionary <BNode, BNode> insertCloneMap = BNode.CloneNodes(islandSegsB, false);
foreach (BNode bn in insertCloneMap.Values)
{
bn.SetParent(dstloop);
}
onIslA = islandSegsA[0];
return(BoundingMode.LeftSurroundsRight);
}
}
// Make sure we have no overlaps of intersections. We currently
// can't handle such things.
HashSet <Utils.NodeTPos> intersections = new HashSet <Utils.NodeTPos>();
foreach (Utils.BezierSubdivSample bss in delCollisions)
{
if (intersections.Add(bss.a.TPos()) == false)
{
return(BoundingMode.Degenerate);
}
if (intersections.Add(bss.b.TPos()) == false)
{
return(BoundingMode.Degenerate);
}
}
// Add everything in the copy in. We'll clip loose ends later to get
// rid of the trash.
Dictionary <BNode, BNode> cloneMap = BNode.CloneNodes(islandSegsB, false);
foreach (BNode bn in cloneMap.Values)
{
bn.SetParent(dstloop);
}
// Well, if we're going to make a copy in its place, that means we need to remap
// all references...
for (int i = 0; i < delCollisions.Count; ++i)
{
Utils.BezierSubdivSample bss = delCollisions[i];
bss.b.node = cloneMap[bss.b.node];
delCollisions[i] = bss;
}
Dictionary <Utils.NodeTPos, BNode.SubdivideInfo> colSlideInfo = SliceCollisionInfo(delCollisions);
Dictionary <Utils.NodeTPos, BNode> createdSubdivs = new Dictionary <Utils.NodeTPos, BNode>();
SplitCollection splitCol = new SplitCollection(dstloop, delCollisions, createdSubdivs);
HashSet <BNode> looseEnds = new HashSet <BNode>();
// Note that nothing from B will be tagged as a loose end. Instead, we're
// forcing the entire island of B to be removed after the Per-Island
// processing.
foreach (Utils.BezierSubdivSample bss in delCollisions)
{
BNode.SubdivideInfo sdiA = colSlideInfo[bss.GetTPosA()];
BNode.SubdivideInfo sdiB = colSlideInfo[bss.GetTPosB()];
float wind = Utils.Vector2Cross(sdiA.subOut, sdiB.subOut);
BNode colNode = createdSubdivs[bss.GetTPosA()];
onIslA = colNode;
if (leftWind > 0 == wind > 0.0f)
{
// A CCW transition will go from A to B.
BNode nA = splitCol.GetPreviousTo(bss.GetTPosA());
BNode nB = splitCol.GetNextTo(bss.GetTPosB());
nA.TanOut = sdiA.prevOut;
nB.TanIn = sdiB.nextIn;
colNode.UseTanIn = bss.a.node.IsLine() == false;
colNode.UseTanOut = bss.b.node.IsLine() == false;
colNode.TanIn = sdiA.subIn;
colNode.TanOut = sdiB.subOut;
nA.next = colNode;
colNode.prev = nA;
nB.prev = colNode;
colNode.next = nB;
looseEnds.Add(bss.b.node);
looseEnds.Add(bss.a.node.next);
}
else
{
// A CW transition will go from the other to it.
BNode nA = splitCol.GetNextTo(bss.GetTPosA());
BNode nB = splitCol.GetPreviousTo(bss.GetTPosB());
nA.TanIn = sdiA.nextIn;
nB.TanOut = sdiB.prevOut;
colNode.UseTanIn = bss.b.node.IsLine() == false;
colNode.UseTanOut = bss.a.node.IsLine() == false;
colNode.TanIn = sdiB.subIn;
colNode.TanOut = sdiA.subOut;
nB.next = colNode;
colNode.prev = nB;
nA.prev = colNode;
colNode.next = nA;
looseEnds.Add(bss.b.node.next);
looseEnds.Add(bss.a.node);
}
}
// Figure out what internal items need to be removed by
// checking which nodes have unmatching connectivity.
ClipLooseEnds(looseEnds);
return(BoundingMode.Collision);
}
/// <summary>
/// Gather intersection data commonly used in boolean trace operations.
/// </summary>
/// <param name="islA">A node on a closed island used as the left path parameter.</param>
/// <param name="islB">A node on a closed island used as the right path parameter.</param>
/// <param name="allNodes">All the nodes found in the loop for islA and islB.</param>
/// <param name="outList">
/// A collection of all the collisions found between islA and islB. This also includes self
/// intersections (such as collisions between islA and other parts of islA).</param>
/// <param name="dictCol">A collection of collisions sorted per-node, and ordered by the
/// point on the beziers they occured.</param>
/// <remarks>The significance of the left and right paths depends on the operation this
/// function is being used for.</remarks>
public static void GatherTraceData(
BNode islA,
BNode islB,
List <BNode> allNodes,
List <Utils.BezierSubdivSample> outList,
Dictionary <BNode, List <Utils.BezierSubdivSample> > dictCol)
{
foreach (BNode bnit in islA.Travel())
{
allNodes.Add(bnit); // Also collect for allNodes
}
foreach (BNode bnit in islB.Travel())
{
allNodes.Add(bnit); // Also collect for allNodes
}
// SCAN AND LOG ALL COLLISIONS
//
//////////////////////////////////////////////////
for (int i = 0; i < allNodes.Count - 1; ++i)
{
BNode bni = allNodes[i];
// This check isn't as robust as it could be. While rare, a segment can create
// a loop that causes an intersection with itself. But, these loops are set up
// assuming loops can never do that.
for (int j = i + 1; j < allNodes.Count; ++j)
{
BNode bnj = allNodes[j];
// Make an output list that checks and cleans for each individual
// collision.
List <Utils.BezierSubdivSample> ol = new List <Utils.BezierSubdivSample>();
Utils.NodeIntersections(bni, bnj, 20, 0.00001f, ol);
Utils.BezierSubdivSample.CleanIntersectionList(ol);
foreach (Utils.BezierSubdivSample bss in ol)
{
// This part is trick and isn't as robust as it could be. Neighboring nodes
// are prone to creating false positives for collising at the ends where
// they are attached. We can't be too aggressive on culling these detections
// out though because it is possible that there could be tiny loops that
// back-track and legitimately collide with their segment neighbors
// *near* the ends. To do this properly we need to bounds check at the
// (cubic) curve roots instead of at extreemly low (0.001) and high (0.99)
// interpolation points.
if (
(bss.a.lEst < 0.001f && bss.a.node.prev == bss.b.node) ||
(bss.a.lEst > 0.99f && bss.a.node.next == bss.b.node))
{
continue;
}
outList.Add(bss);
}
}
}
// ORGANIZE COLLISIONS TO BE USABLE
//
//////////////////////////////////////////////////
// Each node that has a collision has a ordered list of where collisions
// happened. This makes the collision data FAR less unwieldy and more
// usable. Note that because a collision involves two segments colliding
// (ignoring self collisions) each collision will be added to two nodes;
// where the list it's added to will be the "a" segment. If it's originally
// labeled the "b" segment in the collision data, a and b are swapped.
foreach (Utils.BezierSubdivSample bss in outList)
{
List <Utils.BezierSubdivSample> lstA;
List <Utils.BezierSubdivSample> lstB;
// Add a directly.
if (dictCol.TryGetValue(bss.a.node, out lstA) == false)
{
lstA = new List <Utils.BezierSubdivSample>();
dictCol.Add(bss.a.node, lstA);
}
lstA.Add(bss);
// For b, swap b and a before adding so that it's also
// a. This makes it so we don't need to branch to figure
// out which NodeSubRgn (a or b) to reference for a given
// key.
Utils.BezierSubdivSample bssRec = bss.Reciprocal();
if (dictCol.TryGetValue(bss.b.node, out lstB) == false)
{
lstB = new List <Utils.BezierSubdivSample>();
dictCol.Add(bss.b.node, lstB);
}
lstB.Add(bssRec);
}
foreach (List <Utils.BezierSubdivSample> lst in dictCol.Values)
{
lst.Sort(_LexicalSubdivSort);
}
}
