Exemplo n.º 1
0
        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());
        }
Exemplo n.º 2
0
        void PossibleIntersection(SweepEvent e1, SweepEvent e2)
        {
            //	if ((e1->pl == e2->pl) ) // Uncomment these two lines if self-intersecting polygons are not allowed
            //		return false;

            IntersectResult intData          = FindIntersection(e1.segment, e2.segment);
            int             numIntersections = intData.max;
            Vector3         ip1 = intData.point1;

            if (numIntersections == 0)
            {
                return;
            }

            if (numIntersections == 1 && (Misc.PointEquals(e1.p, e2.p) || Misc.PointEquals(e1.otherSE.p, e2.otherSE.p)))
            {
                return;                 // the line segments intersect at an endpoint of both line segments
            }
            if (numIntersections == 2 && e1.polygonType == e2.polygonType)
            {
                return;                  // the line segments overlap, but they belong to the same polygon
            }
            // The line segments associated to e1 and e2 intersect
            if (numIntersections == 1)
            {
                if (!Misc.PointEquals(e1.p, ip1) && !Misc.PointEquals(e1.otherSE.p, ip1))
                {
                    DivideSegment(e1, ip1);                      // if ip1 is not an endpoint of the line segment associated to e1 then divide "e1"
                }
                if (!Misc.PointEquals(e2.p, ip1) && !Misc.PointEquals(e2.otherSE.p, ip1))
                {
                    DivideSegment(e2, ip1);                      // if ip1 is not an endpoint of the line segment associated to e2 then divide "e2"
                }
                return;
            }

            // The line segments overlap
            List <SweepEvent> sortedEvents = new List <SweepEvent>();

            if (Misc.PointEquals(e1.p, e2.p))
            {
                sortedEvents.Add(null);
            }
            else if (Sec(e1, e2))
            {
                sortedEvents.Add(e2);
                sortedEvents.Add(e1);
            }
            else
            {
                sortedEvents.Add(e1);
                sortedEvents.Add(e2);
            }

            if (Misc.PointEquals(e1.otherSE.p, e2.otherSE.p))
            {
                sortedEvents.Add(null);
            }
            else if (Sec(e1.otherSE, e2.otherSE))
            {
                sortedEvents.Add(e2.otherSE);
                sortedEvents.Add(e1.otherSE);
            }
            else
            {
                sortedEvents.Add(e1.otherSE);
                sortedEvents.Add(e2.otherSE);
            }

            if (sortedEvents.Count == 2)               // are both line segments equal?
            {
                e1.edgeType = e1.otherSE.edgeType = EdgeType.NON_CONTRIBUTING;
                e2.edgeType = e2.otherSE.edgeType = ((e1.inOut == e2.inOut) ? EdgeType.SAME_TRANSITION : EdgeType.DIFFERENT_TRANSITION);
                return;
            }

            if (sortedEvents.Count == 3)                // the line segments share an endpoint
            {
                sortedEvents[1].edgeType = sortedEvents[1].otherSE.edgeType = EdgeType.NON_CONTRIBUTING;
                if (sortedEvents[0] != null)                         // is the right endpoint the shared point?
                {
                    sortedEvents[0].otherSE.edgeType = (e1.inOut == e2.inOut) ? EdgeType.SAME_TRANSITION : EdgeType.DIFFERENT_TRANSITION;
                }
                else                                                                            // the shared point is the left endpoint
                {
                    sortedEvents[2].otherSE.edgeType = (e1.inOut == e2.inOut) ? EdgeType.SAME_TRANSITION : EdgeType.DIFFERENT_TRANSITION;
                }
                DivideSegment(sortedEvents[0] != null ? sortedEvents[0] : sortedEvents[2].otherSE, sortedEvents[1].p);
                return;
            }

            if (!sortedEvents[0].Equals(sortedEvents[3].otherSE))
            {             // no segment includes totally the otherSE one
                sortedEvents[1].edgeType = EdgeType.NON_CONTRIBUTING;
                sortedEvents[2].edgeType = (e1.inOut == e2.inOut) ? EdgeType.SAME_TRANSITION : EdgeType.DIFFERENT_TRANSITION;
                DivideSegment(sortedEvents[0], sortedEvents[1].p);
                DivideSegment(sortedEvents[1], sortedEvents[2].p);
                return;
            }

            // one line segment includes the other one
            sortedEvents[1].edgeType = sortedEvents[1].otherSE.edgeType = EdgeType.NON_CONTRIBUTING;
            DivideSegment(sortedEvents[0], sortedEvents[1].p);
            sortedEvents[3].otherSE.edgeType = (e1.inOut == e2.inOut) ? EdgeType.SAME_TRANSITION : EdgeType.DIFFERENT_TRANSITION;
            DivideSegment(sortedEvents[3].otherSE, sortedEvents[2].p);
        }
Exemplo n.º 3
0
 public SweepEvent(Vector3 p, bool isLeft, PolygonType polygonType, SweepEvent otherSweepEvent) : this(p, isLeft, polygonType, otherSweepEvent, EdgeType.NORMAL)
 {
 }