diff options
Diffstat (limited to 'basegfx/source/polygon/b2dpolygontriangulator.cxx')
| -rw-r--r-- | basegfx/source/polygon/b2dpolygontriangulator.cxx | 435 |
1 files changed, 435 insertions, 0 deletions
diff --git a/basegfx/source/polygon/b2dpolygontriangulator.cxx b/basegfx/source/polygon/b2dpolygontriangulator.cxx new file mode 100644 index 000000000..5fbd3960e --- /dev/null +++ b/basegfx/source/polygon/b2dpolygontriangulator.cxx @@ -0,0 +1,435 @@ +/* -*- 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)) + return 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: */ |