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-rw-r--r--basegfx/source/polygon/b2dpolygontriangulator.cxx435
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diff --git a/basegfx/source/polygon/b2dpolygontriangulator.cxx b/basegfx/source/polygon/b2dpolygontriangulator.cxx
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+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * This file incorporates work covered by the following license notice:
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed
+ * with this work for additional information regarding copyright
+ * ownership. The ASF licenses this file to you under the Apache
+ * License, Version 2.0 (the "License"); you may not use this file
+ * except in compliance with the License. You may obtain a copy of
+ * the License at http://www.apache.org/licenses/LICENSE-2.0 .
+ */
+
+#include <basegfx/polygon/b2dpolygontriangulator.hxx>
+#include <basegfx/point/b2dpoint.hxx>
+#include <basegfx/polygon/b2dpolygon.hxx>
+#include <basegfx/polygon/b2dpolypolygon.hxx>
+#include <basegfx/vector/b2dvector.hxx>
+#include <basegfx/polygon/b2dpolygontools.hxx>
+#include <basegfx/polygon/b2dpolypolygontools.hxx>
+#include <basegfx/range/b2drange.hxx>
+#include <basegfx/numeric/ftools.hxx>
+
+#include <algorithm>
+
+namespace basegfx
+{
+ namespace
+ {
+ class EdgeEntry
+ {
+ EdgeEntry* mpNext;
+ B2DPoint maStart;
+ B2DPoint maEnd;
+ double mfAtan2;
+
+ public:
+ EdgeEntry(const B2DPoint& rStart, const B2DPoint& rEnd)
+ : mpNext(nullptr),
+ maStart(rStart),
+ maEnd(rEnd),
+ mfAtan2(0.0)
+ {
+ // make sure edge goes down. If horizontal, let it go to the right (left-handed).
+ bool bSwap(false);
+
+ if(::basegfx::fTools::equal(maStart.getY(), maEnd.getY()))
+ {
+ if(maStart.getX() > maEnd.getX())
+ {
+ bSwap = true;
+ }
+ }
+ else if(maStart.getY() > maEnd.getY())
+ {
+ bSwap = true;
+ }
+
+ if(bSwap)
+ {
+ maStart = rEnd;
+ maEnd = rStart;
+ }
+
+ mfAtan2 = atan2(maEnd.getY() - maStart.getY(), maEnd.getX() - maStart.getX());
+ }
+
+ bool operator<(const EdgeEntry& rComp) const
+ {
+ if(::basegfx::fTools::equal(maStart.getY(), rComp.maStart.getY()))
+ {
+ if(::basegfx::fTools::equal(maStart.getX(), rComp.maStart.getX()))
+ {
+ // same in x and y -> same start point. Sort emitting vectors from left to right.
+ return (mfAtan2 > rComp.mfAtan2);
+ }
+
+ return (maStart.getX() < rComp.maStart.getX());
+ }
+
+ return (maStart.getY() < rComp.maStart.getY());
+ }
+
+ bool operator==(const EdgeEntry& rComp) const
+ {
+ return (maStart.equal(rComp.maStart) && maEnd.equal(rComp.maEnd));
+ }
+
+ bool operator!=(const EdgeEntry& rComp) const
+ {
+ return !(*this == rComp);
+ }
+
+ const B2DPoint& getStart() const { return maStart; }
+ const B2DPoint& getEnd() const { return maEnd; }
+
+ EdgeEntry* getNext() const { return mpNext; }
+ void setNext(EdgeEntry* pNext) { mpNext = pNext; }
+ };
+
+ typedef std::vector< EdgeEntry > EdgeEntries;
+
+ class Triangulator
+ {
+ EdgeEntry* mpList;
+ EdgeEntries maStartEntries;
+ std::vector< std::unique_ptr<EdgeEntry> > maNewEdgeEntries;
+ triangulator::B2DTriangleVector maResult;
+
+ void handleClosingEdge(const B2DPoint& rStart, const B2DPoint& rEnd);
+ bool CheckPointInTriangle(EdgeEntry* pEdgeA, EdgeEntry const * pEdgeB, const B2DPoint& rTestPoint);
+ void createTriangle(const B2DPoint& rA, const B2DPoint& rB, const B2DPoint& rC);
+
+ public:
+ explicit Triangulator(const B2DPolyPolygon& rCandidate);
+
+ const triangulator::B2DTriangleVector& getResult() const { return maResult; }
+ };
+
+ void Triangulator::handleClosingEdge(const B2DPoint& rStart, const B2DPoint& rEnd)
+ {
+ // create an entry, else the comparison might use the wrong edges
+ EdgeEntry aNew(rStart, rEnd);
+ EdgeEntry* pCurr = mpList;
+ EdgeEntry* pPrev = nullptr;
+
+ while(pCurr
+ && pCurr->getStart().getY() <= aNew.getStart().getY()
+ && *pCurr != aNew)
+ {
+ pPrev = pCurr;
+ pCurr = pCurr->getNext();
+ }
+
+ if(pCurr && *pCurr == aNew)
+ {
+ // found closing edge, remove
+ if(pPrev)
+ {
+ pPrev->setNext(pCurr->getNext());
+ }
+ else
+ {
+ mpList = pCurr->getNext();
+ }
+ }
+ else
+ {
+ // insert closing edge
+ EdgeEntry* pNew = new EdgeEntry(aNew);
+ maNewEdgeEntries.emplace_back(pNew);
+ pCurr = mpList;
+ pPrev = nullptr;
+
+ while(pCurr && *pCurr < *pNew)
+ {
+ pPrev = pCurr;
+ pCurr = pCurr->getNext();
+ }
+
+ if(pPrev)
+ {
+ pNew->setNext(pPrev->getNext());
+ pPrev->setNext(pNew);
+ }
+ else
+ {
+ pNew->setNext(mpList);
+ mpList = pNew;
+ }
+ }
+ }
+
+ bool Triangulator::CheckPointInTriangle(EdgeEntry* pEdgeA, EdgeEntry const * pEdgeB, const B2DPoint& rTestPoint)
+ {
+ // inside triangle or on edge?
+ if(utils::isPointInTriangle(pEdgeA->getStart(), pEdgeA->getEnd(), pEdgeB->getEnd(), rTestPoint, true))
+ {
+ // but not on point
+ if(!rTestPoint.equal(pEdgeA->getEnd()) && !rTestPoint.equal(pEdgeB->getEnd()))
+ {
+ // found point in triangle -> split triangle inserting two edges
+ EdgeEntry* pStart = new EdgeEntry(pEdgeA->getStart(), rTestPoint);
+ EdgeEntry* pEnd = new EdgeEntry(*pStart);
+ maNewEdgeEntries.emplace_back(pStart);
+ maNewEdgeEntries.emplace_back(pEnd);
+
+ pStart->setNext(pEnd);
+ pEnd->setNext(pEdgeA->getNext());
+ pEdgeA->setNext(pStart);
+
+ return false;
+ }
+ }
+
+ return true;
+ }
+
+ void Triangulator::createTriangle(const B2DPoint& rA, const B2DPoint& rB, const B2DPoint& rC)
+ {
+ maResult.emplace_back(
+ rA,
+ rB,
+ rC);
+ }
+
+ // consume as long as there are edges
+ Triangulator::Triangulator(const B2DPolyPolygon& rCandidate)
+ : mpList(nullptr)
+ {
+ // add all available edges to the single linked local list which will be sorted
+ // by Y,X,atan2 when adding nodes
+ if(rCandidate.count())
+ {
+ for(sal_uInt32 a(0); a < rCandidate.count(); a++)
+ {
+ const B2DPolygon& aPolygonCandidate(rCandidate.getB2DPolygon(a));
+ const sal_uInt32 nCount(aPolygonCandidate.count());
+
+ if(nCount > 2)
+ {
+ B2DPoint aPrevPnt(aPolygonCandidate.getB2DPoint(nCount - 1));
+
+ for(sal_uInt32 b(0); b < nCount; b++)
+ {
+ B2DPoint aNextPnt(aPolygonCandidate.getB2DPoint(b));
+
+ if( !aPrevPnt.equal(aNextPnt) )
+ {
+ maStartEntries.emplace_back(aPrevPnt, aNextPnt);
+ }
+
+ aPrevPnt = aNextPnt;
+ }
+ }
+ }
+
+ if(!maStartEntries.empty())
+ {
+ // sort initial list
+ std::sort(maStartEntries.begin(), maStartEntries.end());
+
+ // insert to own simply linked list
+ EdgeEntries::iterator aPos(maStartEntries.begin());
+ mpList = &(*aPos++);
+ EdgeEntry* pLast = mpList;
+
+ while(aPos != maStartEntries.end())
+ {
+ EdgeEntry* pEntry = &(*aPos++);
+ pLast->setNext(pEntry);
+ pLast = pEntry;
+ }
+ }
+ }
+
+ while(mpList)
+ {
+ if(mpList->getNext() && mpList->getNext()->getStart().equal(mpList->getStart()))
+ {
+ // next candidate. There are two edges and start point is equal.
+ // Length is not zero.
+ EdgeEntry* pEdgeA = mpList;
+ EdgeEntry* pEdgeB = pEdgeA->getNext();
+
+ if( pEdgeA->getEnd().equal(pEdgeB->getEnd()) )
+ {
+ // start and end equal -> neutral triangle, delete both
+ mpList = pEdgeB->getNext();
+ }
+ else
+ {
+ const B2DVector aLeft(pEdgeA->getEnd() - pEdgeA->getStart());
+ const B2DVector aRight(pEdgeB->getEnd() - pEdgeA->getStart());
+
+ if(getOrientation(aLeft, aRight) == B2VectorOrientation::Neutral)
+ {
+ // edges are parallel and have different length -> neutral triangle,
+ // delete both edges and handle closing edge
+ mpList = pEdgeB->getNext();
+ handleClosingEdge(pEdgeA->getEnd(), pEdgeB->getEnd());
+ }
+ else
+ {
+ // not parallel, look for points inside
+ B2DRange aRange(pEdgeA->getStart(), pEdgeA->getEnd());
+ aRange.expand(pEdgeB->getEnd());
+ EdgeEntry* pTestEdge = pEdgeB->getNext();
+ bool bNoPointInTriangle(true);
+
+ // look for start point in triangle
+ while(bNoPointInTriangle && pTestEdge)
+ {
+ if(aRange.getMaxY() < pTestEdge->getStart().getY())
+ {
+ // edge is below test range and edges are sorted -> stop looking
+ break;
+ }
+ else
+ {
+ // do not look for edges with same start point, they are sorted and cannot end inside.
+ if(!pTestEdge->getStart().equal(pEdgeA->getStart()))
+ {
+ if(aRange.isInside(pTestEdge->getStart()))
+ {
+ bNoPointInTriangle = CheckPointInTriangle(pEdgeA, pEdgeB, pTestEdge->getStart());
+ }
+ }
+ }
+
+ // next candidate
+ pTestEdge = pTestEdge->getNext();
+ }
+
+ if(bNoPointInTriangle)
+ {
+ // look for end point in triangle
+ pTestEdge = pEdgeB->getNext();
+
+ while(bNoPointInTriangle && pTestEdge)
+ {
+ if(aRange.getMaxY() < pTestEdge->getStart().getY())
+ {
+ // edge is below test range and edges are sorted -> stop looking
+ break;
+ }
+ else
+ {
+ // do not look for edges with same end point, they are sorted and cannot end inside.
+ if(!pTestEdge->getEnd().equal(pEdgeA->getStart()))
+ {
+ if(aRange.isInside(pTestEdge->getEnd()))
+ {
+ bNoPointInTriangle = CheckPointInTriangle(pEdgeA, pEdgeB, pTestEdge->getEnd());
+ }
+ }
+ }
+
+ // next candidate
+ pTestEdge = pTestEdge->getNext();
+ }
+ }
+
+ if(bNoPointInTriangle)
+ {
+ // create triangle, remove edges, handle closing edge
+ mpList = pEdgeB->getNext();
+ createTriangle(pEdgeA->getStart(), pEdgeB->getEnd(), pEdgeA->getEnd());
+ handleClosingEdge(pEdgeA->getEnd(), pEdgeB->getEnd());
+ }
+ }
+ }
+ }
+ else
+ {
+ // only one entry at start point, delete it
+ mpList = mpList->getNext();
+ }
+ }
+ }
+
+ } // end of anonymous namespace
+} // end of namespace basegfx
+
+namespace basegfx::triangulator
+{
+ B2DTriangleVector triangulate(const B2DPolygon& rCandidate)
+ {
+ B2DTriangleVector aRetval;
+
+ // subdivide locally (triangulate does not work with beziers), remove double and neutral points
+ B2DPolygon aCandidate(rCandidate.areControlPointsUsed() ? utils::adaptiveSubdivideByAngle(rCandidate) : rCandidate);
+ aCandidate.removeDoublePoints();
+ aCandidate = utils::removeNeutralPoints(aCandidate);
+
+ if(aCandidate.count() == 2)
+ {
+ // candidate IS a triangle, just append
+ aRetval.emplace_back(
+ aCandidate.getB2DPoint(0),
+ aCandidate.getB2DPoint(1),
+ aCandidate.getB2DPoint(2));
+ }
+ else if(aCandidate.count() > 2)
+ {
+ if(utils::isConvex(aCandidate))
+ {
+ // polygon is convex, just use a triangle fan
+ utils::addTriangleFan(aCandidate, aRetval);
+ }
+ else
+ {
+ // polygon is concave.
+ const B2DPolyPolygon aCandPolyPoly(aCandidate);
+ Triangulator aTriangulator(aCandPolyPoly);
+
+ aRetval = aTriangulator.getResult();
+ }
+ }
+
+ return aRetval;
+ }
+
+ B2DTriangleVector triangulate(const B2DPolyPolygon& rCandidate)
+ {
+ B2DTriangleVector aRetval;
+
+ // subdivide locally (triangulate does not work with beziers)
+ B2DPolyPolygon aCandidate(rCandidate.areControlPointsUsed() ? utils::adaptiveSubdivideByAngle(rCandidate) : rCandidate);
+
+ if(aCandidate.count() == 1)
+ {
+ // single polygon -> single polygon triangulation
+ const B2DPolygon& aSinglePolygon(aCandidate.getB2DPolygon(0));
+
+ aRetval = triangulate(aSinglePolygon);
+ }
+ else
+ {
+ Triangulator aTriangulator(aCandidate);
+
+ aRetval = aTriangulator.getResult();
+ }
+
+ return aRetval;
+ }
+} // end of namespace
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */