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Segmentize circular strings the same way in both directions, avoiding problems with tiny gaps/overlaps

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This commit is contained in:
Marco Hugentobler 2017-02-20 16:50:33 +01:00
parent 7732d7314a
commit 3da44134d8
1 changed files with 35 additions and 40 deletions
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75
src/core/geometry/qgscircularstring.cpp
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@ -487,14 +487,25 @@ void QgsCircularString::setPoints( const QgsPointSequence &points )
void QgsCircularString::segmentize( const QgsPointV2& p1, const QgsPointV2& p2, const QgsPointV2& p3, QgsPointSequence &points, double tolerance, SegmentationToleranceType toleranceType ) const void QgsCircularString::segmentize( const QgsPointV2& p1, const QgsPointV2& p2, const QgsPointV2& p3, QgsPointSequence &points, double tolerance, SegmentationToleranceType toleranceType ) const
{ {
bool clockwise = false;
int segSide = segmentSide( p1, p3, p2 );
if ( segSide == -1 )
{
clockwise = true;
}
QgsPointV2 circlePoint1 = clockwise ? p3 : p1;
QgsPointV2 circlePoint2 = p2;
QgsPointV2 circlePoint3 = clockwise ? p1 : p3 ;
//adapted code from postgis //adapted code from postgis
double radius = 0; double radius = 0;
double centerX = 0; double centerX = 0;
double centerY = 0; double centerY = 0;
QgsGeometryUtils::circleCenterRadius( p1, p2, p3, radius, centerX, centerY ); QgsGeometryUtils::circleCenterRadius( circlePoint1, circlePoint2, circlePoint3, radius, centerX, centerY );
int segSide = segmentSide( p1, p3, p2 );
if ( p1 != p3 && ( radius < 0 || qgsDoubleNear( segSide, 0.0 ) ) ) //points are colinear
if ( circlePoint1 != circlePoint3 && ( radius < 0 || qgsDoubleNear( segSide, 0.0 ) ) ) //points are colinear
{ {
points.append( p1 ); points.append( p1 );
points.append( p2 ); points.append( p2 );
@ -502,12 +513,6 @@ void QgsCircularString::segmentize( const QgsPointV2& p1, const QgsPointV2& p2,
return; return;
} }
bool clockwise = false;
if ( segSide == -1 )
{
clockwise = true;
}
double increment = tolerance; //one segment per degree double increment = tolerance; //one segment per degree
if ( toleranceType == QgsAbstractGeometry::MaximumDifference ) if ( toleranceType == QgsAbstractGeometry::MaximumDifference )
{ {
@ -516,27 +521,15 @@ void QgsCircularString::segmentize( const QgsPointV2& p1, const QgsPointV2& p2,
} }
//angles of pt1, pt2, pt3 //angles of pt1, pt2, pt3
double a1 = atan2( p1.y() - centerY, p1.x() - centerX ); double a1 = atan2( circlePoint1.y() - centerY, circlePoint1.x() - centerX );
double a2 = atan2( p2.y() - centerY, p2.x() - centerX ); double a2 = atan2( circlePoint2.y() - centerY, circlePoint2.x() - centerX );
double a3 = atan2( p3.y() - centerY, p3.x() - centerX ); double a3 = atan2( circlePoint3.y() - centerY, circlePoint3.x() - centerX );
if ( clockwise ) /* Adjust a3 up so we can increment from a1 to a3 cleanly */
{ if ( a3 <= a1 )
increment *= -1; a3 += 2.0 * M_PI;
/* Adjust a3 down so we can decrement from a1 to a3 cleanly */ if ( a2 < a1 )
if ( a3 >= a1 ) a2 += 2.0 * M_PI;
a3 -= 2.0 * M_PI;
if ( a2 > a1 )
a2 -= 2.0 * M_PI;
}
else
{
/* Adjust a3 up so we can increment from a1 to a3 cleanly */
if ( a3 <= a1 )
a3 += 2.0 * M_PI;
if ( a2 < a1 )
a2 += 2.0 * M_PI;
}
bool hasZ = is3D(); bool hasZ = is3D();
bool hasM = isMeasure(); bool hasM = isMeasure();
@ -545,8 +538,9 @@ void QgsCircularString::segmentize( const QgsPointV2& p1, const QgsPointV2& p2,
double z = 0; double z = 0;
double m = 0; double m = 0;
points.append( p1 ); QList<QgsPointV2> stringPoints;
if ( p2 != p3 && p1 != p2 ) //draw straight line segment if two points have the same position stringPoints.insert( clockwise ? 0 : stringPoints.size(), circlePoint1 );
if ( circlePoint2 != circlePoint3 && circlePoint1 != circlePoint2 ) //draw straight line segment if two points have the same position
{ {
QgsWkbTypes::Type pointWkbType = QgsWkbTypes::Point; QgsWkbTypes::Type pointWkbType = QgsWkbTypes::Point;
if ( hasZ ) if ( hasZ )
@ -556,16 +550,16 @@ void QgsCircularString::segmentize( const QgsPointV2& p1, const QgsPointV2& p2,
//make sure the curve point p2 is part of the segmentized vertices. But only if p1 != p3 //make sure the curve point p2 is part of the segmentized vertices. But only if p1 != p3
bool addP2 = true; bool addP2 = true;
if ( qgsDoubleNear( p1.x(), p3.x() ) && qgsDoubleNear( p1.y(), p3.y() ) ) if ( qgsDoubleNear( circlePoint1.x(), circlePoint3.x() ) && qgsDoubleNear( circlePoint1.y(), circlePoint3.y() ) )
{ {
addP2 = false; addP2 = false;
} }
for ( double angle = a1 + increment; clockwise ? angle > a3 : angle < a3; angle += increment ) for ( double angle = a1 + increment; angle < a3; angle += increment )
{ {
if (( addP2 && clockwise && angle < a2 ) || ( addP2 && !clockwise && angle > a2 ) ) if (( addP2 && angle > a2 ) )
{ {
points.append( p2 ); stringPoints.insert( clockwise ? 0 : stringPoints.size(), circlePoint2 );
addP2 = false; addP2 = false;
} }
@ -574,23 +568,24 @@ void QgsCircularString::segmentize( const QgsPointV2& p1, const QgsPointV2& p2,
if ( !hasZ && !hasM ) if ( !hasZ && !hasM )
{ {
points.append( QgsPointV2( x, y ) ); stringPoints.insert( clockwise ? 0 : stringPoints.size(), QgsPointV2( x, y ) );
continue; continue;
} }
if ( hasZ ) if ( hasZ )
{ {
z = interpolateArc( angle, a1, a2, a3, p1.z(), p2.z(), p3.z() ); z = interpolateArc( angle, a1, a2, a3, circlePoint1.z(), circlePoint2.z(), circlePoint3.z() );
} }
if ( hasM ) if ( hasM )
{ {
m = interpolateArc( angle, a1, a2, a3, p1.m(), p2.m(), p3.m() ); m = interpolateArc( angle, a1, a2, a3, circlePoint1.m(), circlePoint2.m(), circlePoint3.m() );
} }
points.append( QgsPointV2( pointWkbType, x, y, z, m ) ); stringPoints.insert( clockwise ? 0 : stringPoints.size(), QgsPointV2( pointWkbType, x, y, z, m ) );
} }
} }
points.append( p3 ); stringPoints.insert( clockwise ? 0 : stringPoints.size(), circlePoint3 );
points.append( stringPoints );
} }
int QgsCircularString::segmentSide( const QgsPointV2& pt1, const QgsPointV2& pt3, const QgsPointV2& pt2 ) const int QgsCircularString::segmentSide( const QgsPointV2& pt1, const QgsPointV2& pt3, const QgsPointV2& pt2 ) const