public static List <List <Vector2> > Simplify(List <Vector2> vertices, List <List <Vector2> > holes)
{
var vertexIndexSet = new HashSet <int>();
for (var holeIndex = holes.Count - 1; holeIndex >= 0; holeIndex--)
{
var holeVertexIndex = 0;
if (!TryFindASurgerySegment(vertices, holes, holeIndex, ref holeVertexIndex, new Segment(), vertexIndexSet, out var surgerySegment1))
{
continue;
}
var removedHole = holes[holeIndex];
var surgerySegment = new Segment(removedHole[surgerySegment1.holeVertIndex], vertices[surgerySegment1.vertIndex]);
holeVertexIndex++;
if (!TryFindASurgerySegment(vertices, holes, holeIndex, ref holeVertexIndex, surgerySegment, vertexIndexSet, out var surgerySegment2))
{
continue;
}
//Create subpolygons
var vertexCount = vertices.Count;
var holeVertexCount = removedHole.Count;
var polygon1 = new List <Vector2>();
var startIndex = surgerySegment1.vertIndex;
var endIndex = surgerySegment2.vertIndex;
var index = startIndex;
while (index != endIndex)
{
polygon1.Add(vertices[index]);
index = (index + 1) % vertexCount;
}
polygon1.Add(vertices[endIndex]);
startIndex = surgerySegment2.holeVertIndex;
endIndex = surgerySegment1.holeVertIndex;
index = startIndex;
while (index != endIndex)
{
polygon1.Add(removedHole[index]);
if (--index < 0)
{
index += holeVertexCount;
}
}
polygon1.Add(removedHole[endIndex]);
var polygon2 = new List <Vector2>();
startIndex = surgerySegment2.vertIndex;
endIndex = surgerySegment1.vertIndex;
index = startIndex;
while (index != endIndex)
{
polygon2.Add(vertices[index]);
index = (index + 1) % vertexCount;
}
polygon2.Add(vertices[endIndex]);
startIndex = surgerySegment1.holeVertIndex;
endIndex = surgerySegment2.holeVertIndex;
index = startIndex;
while (index != endIndex)
{
polygon2.Add(removedHole[index]);
if (--index < 0)
{
index += holeVertexCount;
}
}
polygon2.Add(removedHole[endIndex]);
holes.RemoveAt(holeIndex);
var polygon1Holes = new List <List <Vector2> >();
var polygon2Holes = new List <List <Vector2> >();
for (var i = 0; i < holes.Count; i++)
{
var hole = holes[i];
if (PolygonInclude(polygon1, hole[0]))
{
polygon1Holes.Add(hole);
}
else
{
polygon2Holes.Add(hole);
}
}
var subPolygons = new List <List <Vector2> >(2);
if (polygon1Holes.Count > 0)
{
var innerSubPolygons = Simplify(polygon1, polygon1Holes);
for (var i = 0; i < innerSubPolygons.Count; i++)
{
subPolygons.Add(innerSubPolygons[i]);
}
}
else
{
subPolygons.Add(polygon1);
}
if (polygon2Holes.Count > 0)
{
var innerSubPolygons = Simplify(polygon2, polygon2Holes);
for (var i = 0; i < innerSubPolygons.Count; i++)
{
subPolygons.Add(innerSubPolygons[i]);
}
}
else
{
subPolygons.Add(polygon2);
}
return(subPolygons);
}
throw new Exception("Could not find the " + nameof(SurgerySegment) + " couple!");
}
private static bool TryFindASurgerySegment(List <Vector2> vertices, List <List <Vector2> > holes, int holeIndex, ref int holeVertexIndex,
Segment otherSurgerySegment, HashSet <int> vertexIndexSet, out SurgerySegment surgerySegment)
{
var holeCount = holes.Count;
var hole = holes[holeIndex];
var holeVertexCount = hole.Count;
for (; holeVertexIndex < holeVertexCount; holeVertexIndex++)
{
var holeVertex = hole[holeVertexIndex];
var vertexCount = vertices.Count;
for (var vertIndex = 0; vertIndex < vertexCount; vertIndex++)
{
if (vertexIndexSet.Contains(vertIndex))
{
continue;
}
var vertex = vertices[vertIndex];
var segment = new Segment(holeVertex, vertex);
var intersection = Segment.Intersect(segment, otherSurgerySegment);
if (intersection)
{
continue;
}
var nextHoleVertexIndex = (holeVertexIndex + 1) % holeVertexCount;
for (var j = 0; j < holeVertexCount - 2; j++)
{
var index = (nextHoleVertexIndex + j) % holeVertexCount;
var comparedSegment = new Segment(hole[index], hole[(index + 1) % holeVertexCount]);
if (Segment.Intersect(segment, comparedSegment))
{
intersection = true;
break;
}
}
if (intersection)
{
continue;
}
for (var j = 0; j < holeCount; j++)
{
if (j == holeIndex)
{
continue;
}
var comparedHole = holes[j];
if (Segment.Intersect(segment, comparedHole))
{
intersection = true;
break;
}
}
if (intersection)
{
continue;
}
var nextVertexIndex = (vertIndex + 1) % vertexCount;
for (var j = 0; j < vertexCount - 2; j++)
{
var index = (nextVertexIndex + j) % vertexCount;
var comparedSegment = new Segment(vertices[index], vertices[(index + 1) % vertexCount]);
if (Segment.Intersect(segment, comparedSegment))
{
intersection = true;
break;
}
}
if (!intersection)
{
// Debug.DrawLine(segment.p, segment.q, Color.red, 10);
vertexIndexSet.Add(vertIndex);
surgerySegment = new SurgerySegment(holeVertexIndex, vertIndex);
return(true);
}
}
}
surgerySegment = new SurgerySegment();
return(false);
}