/// <summary>
/// Given a shape, fill the session with its closed islands.
/// </summary>
/// <param name="shape">The shape to analyze.</param>
/// <returns>The number of islands extracted.</returns>
public int ExtractFillLoops(BShape shape)
{
int ret = 0;
List <BNode> islandNodes = new List <BNode>();
// For all loops in the shape, extract a single peice of each
// unique circular island.
foreach (BLoop loop in shape.loops)
{
HashSet <BNode> toScan = new HashSet <BNode>(loop.nodes);
while (toScan.Count > 0)
{
BNode bn = Utils.GetFirstInHash(toScan);
BNode.EndpointQuery eq = bn.GetPathLeftmost();
// If cyclical, save a single node to scan the island later
if (eq.result == BNode.EndpointResult.Cyclical)
{
islandNodes.Add(bn);
}
// And remove every part of it from what we're going to
//scan in the future.
BNode it = bn;
while (true)
{
toScan.Remove(it);
it = it.next;
if (it == null || it == eq.node)
{
break;
}
}
}
}
// Extra islands from the looped nodes we've collected.
foreach (BNode bisln in islandNodes)
{
BSample bstart = bisln.sample;
BSample bit = bstart;
FillIsland island = new FillIsland();
this.islands.Add(island);
++ret;
FillSegment firstSeg = null;
FillSegment lastSeg = null;
// For now we're going to assume the samples are well formed.
while (true)
{
FillSegment fs = new FillSegment();
// Transfer positions. We keep a local copy of positions, but by convention,
// the prevPos will match the prev's nextPos, and the nextPos will match
// the next's prevPos.
fs.pos = bit.pos;
island.segments.Add(fs);
if (firstSeg == null)
{
firstSeg = fs;
}
else
{
lastSeg.next = fs;
fs.prev = lastSeg;
}
lastSeg = fs;
bit = bit.next;
if (bit == bstart)
{
break;
}
}
lastSeg.next = firstSeg;
firstSeg.prev = lastSeg;
// Delme
if (island.TestValidity() == false)
{
throw new System.Exception("FillSession.ExtractFillLoops produced invalid island.");
}
}
return(ret);
}
/// <summary>
/// Detect and repair self intersections.
/// </summary>
/// <param name="island">The child island to search-and-operate for self-intersections.</param>
/// <returns></returns>
public int SanatizeIslandIntersections(FillIsland island)
{
if (Utils.verboseDebug)
{
//island.DumpDebugCSV("SanatizeIslandIntersections");
if (island.TestValidity() == false)
{
throw new System.Exception("Error in FillSession.SanitizeIslandIntersections: invalid island parameter.");
}
}
int ret = 0;
HashSet <FillIsland> newIslandsToCheck = new HashSet <FillIsland>();
FillSegment fs = island.GetAStartingPoint();
FillSegment it = fs;
while (true)
{
// We only need to check everything ahead of us back the beginning. Checking
// collisions against stuff we've already traveled over is redundant.
for (FillSegment itOther = it.next; itOther != it; itOther = itOther.next)
{
// Neighboring items detect very slight collision, plus we
// know they can't collide. While in theory we could start itOther one
// more advancement, I'll pass on that for now.
if (itOther.prev == it || itOther.next == it)
{
continue;
}
//island.DumpDebugCSV("SanatizeIslandIntersections_Before");
float s, t;
if (Utils.ProjectSegmentToSegment(
it.pos,
it.next.pos,
itOther.pos,
itOther.next.pos,
out s,
out t) != Utils.SegmentIntersection.Collision)
{
continue;
}
if (s < 0.0f || s > 1.0f || t < 0.0f || t > 1.0f)
{
continue;
}
//island.DumpDebugCSV("SanatizeIslandIntersection_After");
// When a collision happens, we need to split them into two islands
// at the collision point
Vector2 colPt = it.pos + s * (it.next.pos - it.pos);
// First we create the point and set some references
// Stitch "us"
FillSegment newUsStitch = new FillSegment();
newUsStitch.pos = colPt;
newUsStitch.prev = it;
newUsStitch.next = itOther.next;
//
// And stitch "them",
FillSegment newThemStitch = new FillSegment();
newThemStitch.pos = colPt;
newThemStitch.prev = itOther;
newThemStitch.next = it.next;
// And then we patch it all up
it.next = newUsStitch;
newUsStitch.next.prev = newUsStitch;
itOther.next = newThemStitch;
newThemStitch.next.prev = itOther.next;
island.segments.Add(newUsStitch);
// and move them to another island
FillIsland newIsland = new FillIsland();
this.islands.Add(newIsland);
newIsland.segments.Add(itOther);
for (FillSegment sgIt = itOther.next; sgIt != itOther; sgIt = sgIt.next)
{
island.segments.Remove(sgIt);
newIsland.segments.Add(sgIt);
}
}
it = it.next;
// Once we've gone full circle, we've check everything
if (it == fs)
{
break;
}
}
foreach (FillIsland fi in newIslandsToCheck)
{
ret += SanatizeIslandIntersections(fi);
}
return(ret);
}