/// <summary>
/// Executes the polygon clipping operation. Difference operation can result in a region split in two parts - the new region will be added to the regions list if passed.
/// </summary>
public bool Compute(PolygonOp operation, List <Region> regions)
{
int startingContourCount = subject.contours.Count + clipping.contours.Count;
Polygon polygon = ComputeInternal(operation);
if (polygon == null || polygon.contours.Count == 0 || (operation == PolygonOp.UNION && polygon.contours.Count == startingContourCount))
{
if (regions != null && regions.Contains(regionSubject) && (operation == PolygonOp.DIFFERENCE || operation == PolygonOp.XOR))
{
regions.Remove(regionSubject);
}
return(false); // if number of contours equals to starting contours, the operation has not produced anything new - end now.
}
for (int k = 0; k < polygon.contours.Count; k++)
{
Contour cont = polygon.contours[k];
int contPointsCount = cont.points.Count;
for (int j = 0; j < contPointsCount; j++)
{
cont.points[j] /= PRECISION;
}
}
// Returns the contour
List <Vector2> points = polygon.contours[0].points;
if (points.Count < 5 && (operation == PolygonOp.DIFFERENCE || operation == PolygonOp.XOR))
{
if (regions != null)
{
regions.Remove(regionSubject);
}
}
else
{
regionSubject.UpdatePointsAndRect(points);
}
if (regions != null)
{
// New valid extra regions?
for (int k = 1; k < polygon.contours.Count; k++)
{
Region newRegion = new Region(regionSubject.entity, regions.Count);
points = polygon.contours[k].points;
if (points.Count >= 5)
{
newRegion.UpdatePointsAndRect(points);
regions.Add(newRegion);
}
}
}
return(true);
}
public void Compute(PolygonOp operation)
{
Polygon polygon = ComputeInternal(operation);
if (polygon == null)
{
return;
}
for (int k = 0; k < polygon.contours.Count; k++)
{
Contour cont = polygon.contours[k];
for (int j = 0; j < cont.points.Count; j++)
{
cont.points[j] /= PRECISION;
}
}
// Returns the contour
regionSubject.points = polygon.contours[0].points.ToArray();
}
Polygon ComputeInternal(PolygonOp operation)
{
Polygon result = null;
// Test 1 for trivial result case
if (subject.contours.Count * clipping.contours.Count == 0)
{
if (operation == PolygonOp.DIFFERENCE)
{
result = subject;
}
else if (operation == PolygonOp.UNION || operation == PolygonOp.XOR)
{
result = (subject.contours.Count == 0) ? clipping : subject;
}
return(result);
}
// Test 2 for trivial result case
Rectangle subjectBB = subject.boundingBox;
Rectangle clippingBB = clipping.boundingBox;
if (!subjectBB.Intersects(clippingBB))
{
if (operation == PolygonOp.DIFFERENCE)
{
result = subject;
}
if (operation == PolygonOp.UNION || operation == PolygonOp.XOR)
{
result = subject;
foreach (Contour c in clipping.contours)
{
result.AddContour(c);
}
}
return(result);
}
// Add each segment to the eventQueue, sorted from left to right.
foreach (Contour sCont in subject.contours)
{
for (int pParse1 = 0; pParse1 < sCont.points.Count; pParse1++)
{
ProcessSegment(sCont.GetSegment(pParse1), PolygonType.SUBJECT);
}
}
foreach (Contour cCont in clipping.contours)
{
for (int pParse2 = 0; pParse2 < cCont.points.Count; pParse2++)
{
ProcessSegment(cCont.GetSegment(pParse2), PolygonType.CLIPPING);
}
}
Connector connector = new Connector();
// This is the SweepLine. That is, we go through all the polygon edges
// by sweeping from left to right.
SweepEventSet S = new SweepEventSet();
float MINMAX_X = Mathf.Min(subjectBB.right, clippingBB.right);
SweepEvent prev, next;
int panicCounter = 0;
while (!eventQueue.isEmpty)
{
if (panicCounter++ > 100000)
{
break;
}
prev = null;
next = null;
SweepEvent e = eventQueue.Dequeue();
if ((operation == PolygonOp.INTERSECTION && e.p.x > MINMAX_X) || (operation == PolygonOp.DIFFERENCE && e.p.x > subjectBB.right))
{
return(connector.ToPolygonFromLargestLineStrip());
}
if (operation == PolygonOp.UNION && e.p.x > MINMAX_X)
{
// add all the non-processed line segments to the result
if (!e.isLeft)
{
connector.Add(e.segment);
}
while (!eventQueue.isEmpty)
{
e = eventQueue.Dequeue();
if (!e.isLeft)
{
connector.Add(e.segment);
}
}
return(connector.ToPolygonFromLargestLineStrip());
}
if (e.isLeft) // the line segment must be inserted into S
{
int pos = S.Insert(e);
prev = (pos > 0) ? S.eventSet[pos - 1] : null;
next = (pos < S.eventSet.Count - 1) ? S.eventSet[pos + 1] : null;
if (prev == null)
{
e.inside = e.inOut = false;
}
else if (prev.edgeType != EdgeType.NORMAL)
{
if (pos - 2 < 0) // e overlaps with prev
// Not sure how to handle the case when pos - 2 < 0, but judging
// from the C++ implementation this looks like how it should be handled.
{
e.inside = e.inOut = false;
if (prev.polygonType != e.polygonType)
{
e.inside = true;
}
else
{
e.inOut = true;
}
}
else
{
SweepEvent prevTwo = S.eventSet[pos - 2];
if (prev.polygonType == e.polygonType)
{
e.inOut = !prev.inOut;
e.inside = !prevTwo.inOut;
}
else
{
e.inOut = !prevTwo.inOut;
e.inside = !prev.inOut;
}
}
}
else if (e.polygonType == prev.polygonType)
{
e.inside = prev.inside;
e.inOut = !prev.inOut;
}
else
{
e.inside = !prev.inOut;
e.inOut = prev.inside;
}
// Process a possible intersection between "e" and its next neighbor in S
if (next != null)
{
PossibleIntersection(e, next);
}
// Process a possible intersection between "e" and its previous neighbor in S
if (prev != null)
{
PossibleIntersection(prev, e);
}
}
else // the line segment must be removed from S
// Get the next and previous line segments to "e" in S
{
int otherPos = -1;
for (int evt = 0; evt < S.eventSet.Count; evt++)
{
if (e.otherSE.Equals(S.eventSet[evt]))
{
otherPos = evt;
break;
}
}
if (otherPos != -1)
{
prev = (otherPos > 0) ? S.eventSet[otherPos - 1] : null;
next = (otherPos < S.eventSet.Count - 1) ? S.eventSet[otherPos + 1] : null;
}
switch (e.edgeType)
{
case EdgeType.NORMAL:
switch (operation)
{
case PolygonOp.INTERSECTION:
if (e.otherSE.inside)
{
connector.Add(e.segment);
}
break;
case PolygonOp.UNION:
if (!e.otherSE.inside)
{
connector.Add(e.segment);
}
break;
case PolygonOp.DIFFERENCE:
if ((e.polygonType == PolygonType.SUBJECT && !e.otherSE.inside) || (e.polygonType == PolygonType.CLIPPING && e.otherSE.inside))
{
connector.Add(e.segment);
}
break;
case PolygonOp.XOR:
connector.Add(e.segment);
break;
}
break;
case EdgeType.SAME_TRANSITION:
if (operation == PolygonOp.INTERSECTION || operation == PolygonOp.UNION)
{
connector.Add(e.segment);
}
break;
case EdgeType.DIFFERENT_TRANSITION:
if (operation == PolygonOp.DIFFERENCE)
{
connector.Add(e.segment);
}
break;
}
if (otherPos != -1)
{
S.Remove(S.eventSet[otherPos]);
}
if (next != null && prev != null)
{
PossibleIntersection(prev, next);
}
}
}
return(connector.ToPolygonFromLargestLineStrip());
}
public void Compute(PolygonOp operation)
{
subject = ComputeInternal(operation);
}
public void Compute(PolygonOp operation)
{
subject = ComputeInternal(operation);
}
Polygon ComputeInternal(PolygonOp operation)
{
Polygon result = null;
sortedEvents = new List<SweepEvent>();
// Init event queue
eventQueue = new EventQueue();
// Test 1 for trivial result case
if (subject.contours.Count * clipping.contours.Count == 0) {
if (operation == PolygonOp.DIFFERENCE)
result = subject;
else if (operation == PolygonOp.UNION || operation == PolygonOp.XOR)
result = (subject.contours.Count == 0) ? clipping : subject;
return result;
}
// Test 2 for trivial result case
Rectangle subjectBB = subject.boundingBox;
Rectangle clippingBB = clipping.boundingBox;
if (!subjectBB.Intersects(clippingBB)) {
if (operation == PolygonOp.DIFFERENCE)
result = subject;
if (operation == PolygonOp.UNION || operation == PolygonOp.XOR) {
result = subject;
foreach(Contour c in clipping.contours)
result.AddContour(c);
}
return result;
}
// Add each segment to the eventQueue, sorted from left to right.
for(int k=0;k<subject.contours.Count;k++) {
Contour sCont = subject.contours[k];
for (int pParse1=0;pParse1<sCont.points.Count;pParse1++)
ProcessSegment(sCont.GetSegment(pParse1), PolygonType.SUBJECT);
}
for(int k=0;k<clipping.contours.Count;k++) {
Contour cCont = clipping.contours[k];
for (int pParse2=0;pParse2<cCont.points.Count;pParse2++)
ProcessSegment(cCont.GetSegment(pParse2), PolygonType.CLIPPING);
}
Connector connector = new Connector();
// This is the SweepLine. That is, we go through all the polygon edges
// by sweeping from left to right.
SweepEventSet S = new SweepEventSet();
double MINMAX_X = Math.Min(subjectBB.right, clippingBB.right) + Point.PRECISION;
SweepEvent prev, next;
int panicCounter = 0; // This is a safety check to prevent infinite loops (very rare but could happen due to floating-point issues with a high number of points)
while (!eventQueue.isEmpty)
{
if (panicCounter++>10000) {
Debug.Log("PANIC!");
break;
}
prev = null;
next = null;
SweepEvent e = eventQueue.Dequeue();
if ((operation == PolygonOp.INTERSECTION && e.p.x > MINMAX_X) || (operation == PolygonOp.DIFFERENCE && e.p.x > subjectBB.right + Point.PRECISION))
return connector.ToPolygonFromLargestLineStrip();
if (operation == PolygonOp.UNION && e.p.x > MINMAX_X) {
// add all the non-processed line segments to the result
if (!e.isLeft)
connector.Add(e.segment);
while (!eventQueue.isEmpty) {
e = eventQueue.Dequeue();
if (!e.isLeft)
connector.Add(e.segment);
}
return connector.ToPolygonFromLargestLineStrip();
}
if (e.isLeft) { // the line segment must be inserted into S
int pos = S.Insert(e);
prev = (pos > 0) ? S.eventSet[pos - 1] : null;
next = (pos < S.eventSet.Count - 1) ? S.eventSet[pos + 1] : null;
if (prev == null) {
e.inside = e.inOut = false;
} else if (prev.edgeType != EdgeType.NORMAL) {
if (pos - 2 < 0) { // e overlaps with prev
// Not sure how to handle the case when pos - 2 < 0, but judging
// from the C++ implementation this looks like how it should be handled.
e.inside = e.inOut = false;
if (prev.polygonType != e.polygonType)
e.inside = true;
else
e.inOut = true;
} else {
SweepEvent prevTwo = S.eventSet[pos - 2];
if (prev.polygonType == e.polygonType) {
e.inOut = !prev.inOut;
e.inside = !prevTwo.inOut;
} else {
e.inOut = !prevTwo.inOut;
e.inside = !prev.inOut;
}
}
} else if (e.polygonType == prev.polygonType) {
e.inside = prev.inside;
e.inOut = !prev.inOut;
} else {
e.inside = !prev.inOut;
e.inOut = prev.inside;
}
// Process a possible intersection between "e" and its next neighbor in S
if (next != null)
PossibleIntersection(e, next);
// Process a possible intersection between "e" and its previous neighbor in S
if (prev != null)
PossibleIntersection(prev, e);
} else { // the line segment must be removed from S
// Get the next and previous line segments to "e" in S
int otherPos = -1;
for (int evt=0;evt<S.eventSet.Count;evt++) {
if (e.otherSE.Equals(S.eventSet[evt])) {
otherPos = evt;
break;
}
}
if (otherPos != -1) {
prev = (otherPos > 0) ? S.eventSet[otherPos - 1] : null;
next = (otherPos < S.eventSet.Count - 1) ? S.eventSet[otherPos + 1] : null;
}
switch (e.edgeType) {
case EdgeType.NORMAL:
switch (operation) {
case PolygonOp.INTERSECTION:
if (e.otherSE.inside)
connector.Add(e.segment);
break;
case PolygonOp.UNION:
if (!e.otherSE.inside)
connector.Add(e.segment);
break;
case PolygonOp.DIFFERENCE:
if ((e.polygonType == PolygonType.SUBJECT && !e.otherSE.inside) || (e.polygonType == PolygonType.CLIPPING && e.otherSE.inside))
connector.Add(e.segment);
break;
case PolygonOp.XOR:
connector.Add (e.segment);
break;
}
break;
case EdgeType.SAME_TRANSITION:
if (operation == PolygonOp.INTERSECTION || operation == PolygonOp.UNION)
connector.Add(e.segment);
break;
case EdgeType.DIFFERENT_TRANSITION:
if (operation == PolygonOp.DIFFERENCE)
connector.Add(e.segment);
break;
}
if (otherPos != -1)
S.Remove(S.eventSet[otherPos]);
if (next != null && prev != null)
PossibleIntersection(prev, next);
}
}
return connector.ToPolygonFromLargestLineStrip();
}