/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
* This file is part of the LibreOffice project.
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* 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/b2dpolygonclipper.hxx>
#include <basegfx/polygon/b2dpolygontools.hxx>
#include <basegfx/numeric/ftools.hxx>
#include <basegfx/matrix/b2dhommatrix.hxx>
#include <basegfx/polygon/b2dpolypolygoncutter.hxx>
#include <basegfx/polygon/b2dpolygoncutandtouch.hxx>
#include <basegfx/polygon/b2dpolypolygontools.hxx>
#include <basegfx/curve/b2dcubicbezier.hxx>
#include <basegfx/utils/rectcliptools.hxx>
#include <basegfx/matrix/b2dhommatrixtools.hxx>
namespace basegfx
{
namespace utils
{
B2DPolyPolygon clipPolygonOnParallelAxis(const B2DPolygon& rCandidate, bool bParallelToXAxis, bool bAboveAxis, double fValueOnOtherAxis, bool bStroke)
{
B2DPolyPolygon aRetval;
if(rCandidate.count())
{
const B2DRange aCandidateRange(getRange(rCandidate));
if(bParallelToXAxis && fTools::moreOrEqual(aCandidateRange.getMinY(), fValueOnOtherAxis))
{
// completely above and on the clip line. also true for curves.
if(bAboveAxis)
{
// add completely
aRetval.append(rCandidate);
}
}
else if(bParallelToXAxis && fTools::lessOrEqual(aCandidateRange.getMaxY(), fValueOnOtherAxis))
{
// completely below and on the clip line. also true for curves.
if(!bAboveAxis)
{
// add completely
aRetval.append(rCandidate);
}
}
else if(!bParallelToXAxis && fTools::moreOrEqual(aCandidateRange.getMinX(), fValueOnOtherAxis))
{
// completely right of and on the clip line. also true for curves.
if(bAboveAxis)
{
// add completely
aRetval.append(rCandidate);
}
}
else if(!bParallelToXAxis && fTools::lessOrEqual(aCandidateRange.getMaxX(), fValueOnOtherAxis))
{
// completely left of and on the clip line. also true for curves.
if(!bAboveAxis)
{
// add completely
aRetval.append(rCandidate);
}
}
else
{
// add cuts with axis to polygon, including bezier segments
// Build edge to cut with. Make it a little big longer than needed for
// numerical stability. We want to cut against the edge seen as endless
// ray here, but addPointsAtCuts() will limit itself to the
// edge's range ]0.0 .. 1.0[.
const double fSmallExtension((aCandidateRange.getWidth() + aCandidateRange.getHeight()) * (0.5 * 0.1));
const B2DPoint aStart(
bParallelToXAxis ? aCandidateRange.getMinX() - fSmallExtension : fValueOnOtherAxis,
bParallelToXAxis ? fValueOnOtherAxis : aCandidateRange.getMinY() - fSmallExtension);
const B2DPoint aEnd(
bParallelToXAxis ? aCandidateRange.getMaxX() + fSmallExtension : fValueOnOtherAxis,
bParallelToXAxis ? fValueOnOtherAxis : aCandidateRange.getMaxY() + fSmallExtension);
const B2DPolygon aCandidate(addPointsAtCuts(rCandidate, aStart, aEnd));
const sal_uInt32 nPointCount(aCandidate.count());
const sal_uInt32 nEdgeCount(aCandidate.isClosed() ? nPointCount : nPointCount - 1);
B2DCubicBezier aEdge;
B2DPolygon aRun;
for(sal_uInt32 a(0); a < nEdgeCount; a++)
{
aCandidate.getBezierSegment(a, aEdge);
const B2DPoint aTestPoint(aEdge.interpolatePoint(0.5));
const bool bInside(bParallelToXAxis ?
fTools::moreOrEqual(aTestPoint.getY(), fValueOnOtherAxis) == bAboveAxis :
fTools::moreOrEqual(aTestPoint.getX(), fValueOnOtherAxis) == bAboveAxis);
if(bInside)
{
if(!aRun.count() || !aRun.getB2DPoint(aRun.count() - 1).equal(aEdge.getStartPoint()))
{
aRun.append(aEdge.getStartPoint());
}
if(aEdge.isBezier())
{
aRun.appendBezierSegment(aEdge.getControlPointA(), aEdge.getControlPointB(), aEdge.getEndPoint());
}
else
{
aRun.append(aEdge.getEndPoint());
}
}
else
{
if(bStroke && aRun.count())
{
aRetval.append(aRun);
aRun.clear();
}
}
}
if(aRun.count())
{
if(bStroke)
{
// try to merge this last and first polygon; they may have been
// the former polygon's start/end point
if(aRetval.count())
{
const B2DPolygon aStartPolygon(aRetval.getB2DPolygon(0));
if(aStartPolygon.count() && aStartPolygon.getB2DPoint(0).equal(aRun.getB2DPoint(aRun.count() - 1)))
{
// append start polygon to aRun, remove from result set
aRun.append(aStartPolygon); aRun.removeDoublePoints();
aRetval.remove(0);
}
}
aRetval.append(aRun);
}
else
{
// set closed flag and correct last point (which is added double now).
closeWithGeometryChange(aRun);
aRetval.append(aRun);
}
}
}
}
return aRetval;
}
B2DPolyPolygon clipPolyPolygonOnParallelAxis(const B2DPolyPolygon& rCandidate, bool bParallelToXAxis, bool bAboveAxis, double fValueOnOtherAxis, bool bStroke)
{
const sal_uInt32 nPolygonCount(rCandidate.count());
B2DPolyPolygon aRetval;
for(sal_uInt32 a(0); a < nPolygonCount; a++)
{
const B2DPolyPolygon aClippedPolyPolygon(clipPolygonOnParallelAxis(rCandidate.getB2DPolygon(a), bParallelToXAxis, bAboveAxis, fValueOnOtherAxis, bStroke));
if(aClippedPolyPolygon.count())
{
aRetval.append(aClippedPolyPolygon);
}
}
return aRetval;
}
B2DPolyPolygon clipPolygonOnRange(const B2DPolygon& rCandidate, const B2DRange& rRange, bool bInside, bool bStroke)
{
const sal_uInt32 nCount(rCandidate.count());
B2DPolyPolygon aRetval;
if(!nCount)
{
// source is empty
return aRetval;
}
if(rRange.isEmpty())
{
if(bInside)
{
// nothing is inside an empty range
return aRetval;
}
else
{
// everything is outside an empty range
return B2DPolyPolygon(rCandidate);
}
}
const B2DRange aCandidateRange(getRange(rCandidate));
if(rRange.isInside(aCandidateRange))
{
// candidate is completely inside given range
if(bInside)
{
// nothing to do
return B2DPolyPolygon(rCandidate);
}
else
{
// nothing is outside, then
return aRetval;
}
}
if(!bInside)
{
// cutting off the outer parts of filled polygons at parallel
// lines to the axes is only possible for the inner part, not for
// the outer part which means cutting a hole into the original polygon.
// This is because the inner part is a logical AND-operation of
// the four implied half-planes, but the outer part is not.
// It is possible for strokes, but with creating unnecessary extra
// cuts, so using clipPolygonOnPolyPolygon is better there, too.
// This needs to be done with the topology knowledge and is unfortunately
// more expensive, too.
const B2DPolygon aClip(createPolygonFromRect(rRange));
return clipPolygonOnPolyPolygon(rCandidate, B2DPolyPolygon(aClip), bInside, bStroke);
}
// clip against the four axes of the range
// against X-Axis, lower value
aRetval = clipPolygonOnParallelAxis(rCandidate, true, bInside, rRange.getMinY(), bStroke);
if(aRetval.count())
{
// against Y-Axis, lower value
if(aRetval.count() == 1)
{
aRetval = clipPolygonOnParallelAxis(aRetval.getB2DPolygon(0), false, bInside, rRange.getMinX(), bStroke);
}
else
{
aRetval = clipPolyPolygonOnParallelAxis(aRetval, false, bInside, rRange.getMinX(), bStroke);
}
if(aRetval.count())
{
// against X-Axis, higher value
if(aRetval.count() == 1)
{
aRetval = clipPolygonOnParallelAxis(aRetval.getB2DPolygon(0), true, !bInside, rRange.getMaxY(), bStroke);
}
else
{
aRetval = clipPolyPolygonOnParallelAxis(aRetval, true, !bInside, rRange.getMaxY(), bStroke);
}
if(aRetval.count())
{
// against Y-Axis, higher value
if(aRetval.count() == 1)
{
aRetval = clipPolygonOnParallelAxis(aRetval.getB2DPolygon(0), false, !bInside, rRange.getMaxX(), bStroke);
}
else
{
aRetval = clipPolyPolygonOnParallelAxis(aRetval, false, !bInside, rRange.getMaxX(), bStroke);
}
}
}
}
return aRetval;
}
B2DPolyPolygon clipPolyPolygonOnRange(const B2DPolyPolygon& rCandidate, const B2DRange& rRange, bool bInside, bool bStroke)
{
const sal_uInt32 nPolygonCount(rCandidate.count());
B2DPolyPolygon aRetval;
if(!nPolygonCount)
{
// source is empty
return aRetval;
}
if(rRange.isEmpty())
{
if(bInside)
{
// nothing is inside an empty range
return aRetval;
}
else
{
// everything is outside an empty range
return rCandidate;
}
}
if(bInside)
{
for(sal_uInt32 a(0); a < nPolygonCount; a++)
{
const B2DPolyPolygon aClippedPolyPolygon(clipPolygonOnRange(rCandidate.getB2DPolygon(a), rRange, bInside, bStroke));
if(aClippedPolyPolygon.count())
{
aRetval.append(aClippedPolyPolygon);
}
}
}
else
{
// for details, see comment in clipPolygonOnRange for the "cutting off
// the outer parts of filled polygons at parallel lines" explanations
const B2DPolygon aClip(createPolygonFromRect(rRange));
return clipPolyPolygonOnPolyPolygon(rCandidate, B2DPolyPolygon(aClip), bInside, bStroke);
}
return aRetval;
}
B2DPolyPolygon clipPolyPolygonOnPolyPolygon(const B2DPolyPolygon& rCandidate, const B2DPolyPolygon& rClip, bool bInside, bool bStroke)
{
B2DPolyPolygon aRetval;
if(rCandidate.count() && rClip.count())
{
// one or both are no rectangle - go the hard way and clip PolyPolygon
// against PolyPolygon...
if(bStroke)
{
// line clipping, create line snippets by first adding all cut points and
// then marching along the edges and detecting if they are inside or outside
// the clip polygon
for(sal_uInt32 a(0); a < rCandidate.count(); a++)
{
// add cuts with clip to polygon, including bezier segments
const B2DPolygon aCandidate(addPointsAtCuts(rCandidate.getB2DPolygon(a), rClip));
const sal_uInt32 nPointCount(aCandidate.count());
const sal_uInt32 nEdgeCount(aCandidate.isClosed() ? nPointCount : nPointCount - 1);
B2DCubicBezier aEdge;
B2DPolygon aRun;
for(sal_uInt32 b(0); b < nEdgeCount; b++)
{
aCandidate.getBezierSegment(b, aEdge);
const B2DPoint aTestPoint(aEdge.interpolatePoint(0.5));
const bool bIsInside(utils::isInside(rClip, aTestPoint) == bInside);
if(bIsInside)
{
if(!aRun.count())
{
aRun.append(aEdge.getStartPoint());
}
if(aEdge.isBezier())
{
aRun.appendBezierSegment(aEdge.getControlPointA(), aEdge.getControlPointB(), aEdge.getEndPoint());
}
else
{
aRun.append(aEdge.getEndPoint());
}
}
else
{
if(aRun.count())
{
aRetval.append(aRun);
aRun.clear();
}
}
}
if(aRun.count())
{
// try to merge this last and first polygon; they may have been
// the former polygon's start/end point
if(aRetval.count())
{
const B2DPolygon aStartPolygon(aRetval.getB2DPolygon(0));
if(aStartPolygon.count() && aStartPolygon.getB2DPoint(0).equal(aRun.getB2DPoint(aRun.count() - 1)))
{
// append start polygon to aRun, remove from result set
aRun.append(aStartPolygon); aRun.removeDoublePoints();
aRetval.remove(0);
}
}
aRetval.append(aRun);
}
}
}
else
{
// check for simplification with ranges if !bStroke (handling as stroke is more simple),
// but also only when bInside, else the simplification may lead to recursive calls (see
// calls to clipPolyPolygonOnPolyPolygon in clipPolyPolygonOnRange and clipPolygonOnRange)
if (bInside && basegfx::utils::isRectangle(rClip))
{
// #i125349# detect if both given PolyPolygons are indeed ranges
if (basegfx::utils::isRectangle(rCandidate))
{
// both are rectangle
if(rCandidate.getB2DRange().equal(rClip.getB2DRange()))
{
// if both are equal -> no change
return rCandidate;
}
else
{
// not equal -> create new intersection from both ranges,
// but much cheaper based on the ranges
basegfx::B2DRange aIntersectionRange(rCandidate.getB2DRange());
aIntersectionRange.intersect(rClip.getB2DRange());
if(aIntersectionRange.isEmpty())
{
// no common IntersectionRange -> the clip will be empty
return B2DPolyPolygon();
}
else
{
// use common aIntersectionRange as result, convert
// to expected utils::PolyPolygon form
return basegfx::B2DPolyPolygon(
basegfx::utils::createPolygonFromRect(aIntersectionRange));
}
}
}
else
{
// rClip is rectangle -> clip rCandidate on rRectangle, use the much
// cheaper and numerically more stable clipping against a range
return clipPolyPolygonOnRange(rCandidate, rClip.getB2DRange(), bInside, bStroke);
}
}
// area clipping
B2DPolyPolygon aMergePolyPolygonA(rClip);
// First solve all polygon-self and polygon-polygon intersections.
// Also get rid of some not-needed polygons (neutral, no area -> when
// no intersections, these are tubes).
// Now it is possible to correct the orientations in the cut-free
// polygons to values corresponding to painting the utils::PolyPolygon with
// a XOR-WindingRule.
aMergePolyPolygonA = solveCrossovers(aMergePolyPolygonA);
aMergePolyPolygonA = stripNeutralPolygons(aMergePolyPolygonA);
aMergePolyPolygonA = correctOrientations(aMergePolyPolygonA);
if(!bInside)
{
// if we want to get the outside of the clip polygon, make
// it a 'Hole' in topological sense
aMergePolyPolygonA.flip();
}
B2DPolyPolygon aMergePolyPolygonB(rCandidate);
// prepare 2nd source polygon in same way
aMergePolyPolygonB = solveCrossovers(aMergePolyPolygonB);
aMergePolyPolygonB = stripNeutralPolygons(aMergePolyPolygonB);
aMergePolyPolygonB = correctOrientations(aMergePolyPolygonB);
// to clip against each other, concatenate and solve all
// polygon-polygon crossovers. polygon-self do not need to
// be solved again, they were solved in the preparation.
aRetval.append(aMergePolyPolygonA);
aRetval.append(aMergePolyPolygonB);
aRetval = solveCrossovers(aRetval);
// now remove neutral polygons (closed, but no area). In a last
// step throw away all polygons which have a depth of less than 1
// which means there was no logical AND at their position. For the
// not-inside solution, the clip was flipped to define it as 'Hole',
// so the removal rule is different here; remove all with a depth
// of less than 0 (aka holes).
aRetval = stripNeutralPolygons(aRetval);
aRetval = stripDispensablePolygons(aRetval, bInside);
}
}
return aRetval;
}
B2DPolyPolygon clipPolygonOnPolyPolygon(const B2DPolygon& rCandidate, const B2DPolyPolygon& rClip, bool bInside, bool bStroke)
{
B2DPolyPolygon aRetval;
if(rCandidate.count() && rClip.count())
{
aRetval = clipPolyPolygonOnPolyPolygon(B2DPolyPolygon(rCandidate), rClip, bInside, bStroke);
}
return aRetval;
}
/*
* let a plane be defined as
*
* v.n+d=0
*
* and a ray be defined as
*
* a+(b-a)*t=0
*
* substitute and rearranging yields
*
* t = -(a.n+d)/(n.(b-a))
*
* if the denominator is zero, the line is either
* contained in the plane or parallel to the plane.
* in either case, there is no intersection.
* if numerator and denominator are both zero, the
* ray is contained in the plane.
*
*/
struct scissor_plane {
double nx,ny; // plane normal
double d; // [-] minimum distance from origin
sal_uInt32 clipmask; // clipping mask, e.g. 1000 1000
};
/*
*
* polygon clipping rules (straight out of Foley and Van Dam)
* ===========================================================
* current |next |emit
* ____________________________________
* inside |inside |next
* inside |outside |intersect with clip plane
* outside |outside |nothing
* outside |inside |intersect with clip plane follwed by next
*
*/
sal_uInt32 scissorLineSegment( ::basegfx::B2DPoint *in_vertex, // input buffer
sal_uInt32 in_count, // number of verts in input buffer
::basegfx::B2DPoint *out_vertex, // output buffer
scissor_plane const *pPlane, // scissoring plane
const ::basegfx::B2DRectangle &rR ) // clipping rectangle
{
sal_uInt32 out_count=0;
// process all the verts
for(sal_uInt32 i=0; i<in_count; i++) {
// vertices are relative to the coordinate
// system defined by the rectangle.
::basegfx::B2DPoint *curr = &in_vertex[i];
::basegfx::B2DPoint *next = &in_vertex[(i+1)%in_count];
// perform clipping judgement & mask against current plane.
sal_uInt32 clip = pPlane->clipmask & ((getCohenSutherlandClipFlags(*curr,rR)<<4)|getCohenSutherlandClipFlags(*next,rR));
if(clip==0) { // both verts are inside
out_vertex[out_count++] = *next;
}
else if((clip&0x0f) && (clip&0xf0)) { // both verts are outside
}
else if((clip&0x0f) && (clip&0xf0)==0) { // curr is inside, next is outside
// direction vector from 'current' to 'next', *not* normalized
// to bring 't' into the [0<=x<=1] interval.
::basegfx::B2DPoint dir((*next)-(*curr));
double denominator = ( pPlane->nx*dir.getX() +
pPlane->ny*dir.getY() );
double numerator = ( pPlane->nx*curr->getX() +
pPlane->ny*curr->getY() +
pPlane->d );
double t = -numerator/denominator;
// calculate the actual point of intersection
::basegfx::B2DPoint intersection( curr->getX()+t*dir.getX(),
curr->getY()+t*dir.getY() );
out_vertex[out_count++] = intersection;
}
else if((clip&0x0f)==0 && (clip&0xf0)) { // curr is outside, next is inside
// direction vector from 'current' to 'next', *not* normalized
// to bring 't' into the [0<=x<=1] interval.
::basegfx::B2DPoint dir((*next)-(*curr));
double denominator = ( pPlane->nx*dir.getX() +
pPlane->ny*dir.getY() );
double numerator = ( pPlane->nx*curr->getX() +
pPlane->ny*curr->getY() +
pPlane->d );
double t = -numerator/denominator;
// calculate the actual point of intersection
::basegfx::B2DPoint intersection( curr->getX()+t*dir.getX(),
curr->getY()+t*dir.getY() );
out_vertex[out_count++] = intersection;
out_vertex[out_count++] = *next;
}
}
return out_count;
}
B2DPolygon clipTriangleListOnRange( const B2DPolygon& rCandidate,
const B2DRange& rRange )
{
B2DPolygon aResult;
if( !(rCandidate.count()%3) )
{
const int scissor_plane_count = 4;
scissor_plane sp[scissor_plane_count];
sp[0].nx = +1.0;
sp[0].ny = +0.0;
sp[0].d = -(rRange.getMinX());
sp[0].clipmask = (RectClipFlags::LEFT << 4) | RectClipFlags::LEFT; // 0001 0001
sp[1].nx = -1.0;
sp[1].ny = +0.0;
sp[1].d = +(rRange.getMaxX());
sp[1].clipmask = (RectClipFlags::RIGHT << 4) | RectClipFlags::RIGHT; // 0010 0010
sp[2].nx = +0.0;
sp[2].ny = +1.0;
sp[2].d = -(rRange.getMinY());
sp[2].clipmask = (RectClipFlags::TOP << 4) | RectClipFlags::TOP; // 0100 0100
sp[3].nx = +0.0;
sp[3].ny = -1.0;
sp[3].d = +(rRange.getMaxY());
sp[3].clipmask = (RectClipFlags::BOTTOM << 4) | RectClipFlags::BOTTOM; // 1000 1000
// retrieve the number of vertices of the triangulated polygon
const sal_uInt32 nVertexCount = rCandidate.count();
if(nVertexCount)
{
// Upper bound for the maximal number of vertices when intersecting an
// axis-aligned rectangle with a triangle in E2
// The rectangle and the triangle are in general position, and have 4 and 3
// vertices, respectively.
// Lemma: Since the rectangle is a convex polygon ( see
// http://mathworld.wolfram.com/ConvexPolygon.html for a definition), and
// has no holes, it follows that any straight line will intersect the
// rectangle's border line at utmost two times (with the usual
// tie-breaking rule, if the intersection exactly hits an already existing
// rectangle vertex, that this intersection is only attributed to one of
// the adjoining edges). Thus, having a rectangle intersected with
// a half-plane (one side of a straight line denotes 'inside', the
// other 'outside') will at utmost add _one_ vertex to the resulting
// intersection polygon (adding two intersection vertices, and removing at
// least one rectangle vertex):
// *
// +--+-----------------+
// | * |
// |* |
// + |
// *| |
// * | |
// +--------------------+
// Proof: If the straight line intersects the rectangle two
// times, it does so for distinct edges, i.e. the intersection has
// minimally one of the rectangle's vertices on either side of the straight
// line (but maybe more). Thus, the intersection with a half-plane has
// minimally _one_ rectangle vertex removed from the resulting clip
// polygon, and therefore, a clip against a half-plane has the net effect
// of adding at utmost _one_ vertex to the resulting clip polygon.
// Theorem: The intersection of a rectangle and a triangle results in a
// polygon with at utmost 7 vertices.
// Proof: The inside of the triangle can be described as the consecutive
// intersection with three half-planes. Together with the lemma above, this
// results in at utmost 3 additional vertices added to the already existing 4
// rectangle vertices.
// This upper bound is attained with the following example configuration:
// *
// ***
// ** *
// ** *
// ** *
// ** *
// ** *
// ** *
// ** *
// ** *
// ** *
// ----*2--------3 *
// | ** |*
// 1* 4
// **| *|
// ** | * |
// **| * |
// 7* * |
// --*6-----5-----
// ** *
// **
// As we need to scissor all triangles against the
// output rectangle we employ an output buffer for the
// resulting vertices. the question is how large this
// buffer needs to be compared to the number of
// incoming vertices. this buffer needs to hold at
// most the number of original vertices times '7'. see
// figure above for an example. scissoring triangles
// with the cohen-sutherland line clipping algorithm
// as implemented here will result in a triangle fan
// which will be rendered as separate triangles to
// avoid pipeline stalls for each scissored
// triangle. creating separate triangles from a
// triangle fan produces (n-2)*3 vertices where n is
// the number of vertices of the original triangle
// fan. for the maximum number of 7 vertices of
// resulting triangle fans we therefore need 15 times
// the number of original vertices.
//const size_t nBufferSize = sizeof(vertex)*(nVertexCount*16);
//vertex *pVertices = (vertex*)alloca(nBufferSize);
//sal_uInt32 nNumOutput = 0;
// we need to clip this triangle against the output rectangle
// to ensure that the resulting texture coordinates are in
// the valid range from [0<=st<=1]. under normal circumstances
// we could use the BORDERCOLOR renderstate but some cards
// seem to ignore this feature.
::basegfx::B2DPoint stack[3];
unsigned int clipflag = 0;
for(sal_uInt32 nIndex=0; nIndex<nVertexCount; ++nIndex)
{
// rotate stack
stack[0] = stack[1];
stack[1] = stack[2];
stack[2] = rCandidate.getB2DPoint(nIndex);
// clipping judgement
clipflag |= unsigned(!(rRange.isInside(stack[2])));
if(nIndex > 1)
{
// consume vertices until a single separate triangle has been visited.
if(!((nIndex+1)%3))
{
// if any of the last three vertices was outside
// we need to scissor against the destination rectangle
if(clipflag & 7)
{
::basegfx::B2DPoint buf0[16];
::basegfx::B2DPoint buf1[16];
sal_uInt32 vertex_count = 3;
// clip against all 4 planes passing the result of
// each plane as the input to the next using a double buffer
vertex_count = scissorLineSegment(stack,vertex_count,buf1,&sp[0],rRange);
vertex_count = scissorLineSegment(buf1,vertex_count,buf0,&sp[1],rRange);
vertex_count = scissorLineSegment(buf0,vertex_count,buf1,&sp[2],rRange);
vertex_count = scissorLineSegment(buf1,vertex_count,buf0,&sp[3],rRange);
if(vertex_count >= 3)
{
// convert triangle fan back to triangle list.
::basegfx::B2DPoint v0(buf0[0]);
::basegfx::B2DPoint v1(buf0[1]);
for(sal_uInt32 i=2; i<vertex_count; ++i)
{
::basegfx::B2DPoint v2(buf0[i]);
aResult.append(v0);
aResult.append(v1);
aResult.append(v2);
v1 = v2;
}
}
}
else
{
// the last triangle has not been altered, simply copy to result
for(basegfx::B2DPoint & i : stack)
aResult.append(i);
}
}
}
clipflag <<= 1;
}
}
}
return aResult;
}
} // end of namespace utils
} // end of namespace basegfx
/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
↑ V547 Expression '!bInside' is always false.
↑ V547 Expression '!bInside' is always false.
↑ V547 Expression '!bInside' is always false.
↑ V547 Expression '!bInside' is always false.