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fix(elevation_profile): add fix when intersecting polygons vs wall.

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In case the geometry is invalid, we shift all coordinates by an epsilon to ensure the 2D equivalent will be topologically correct.

This is just a fix, a proper 3D geometry library is needed (like SFCGAL)!
This commit is contained in:
bdm-oslandia 2024-02-27 09:37:52 +01:00 committed by Nyall Dawson
parent ce96dee6b5
commit 8a9824b0b3
1 changed files with 39 additions and 2 deletions
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41
src/core/vector/qgsvectorlayerprofilegenerator.cpp
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@ -1340,9 +1340,46 @@ bool QgsVectorLayerProfileGenerator::generateProfileForPolygons()
QString error;
if ( mProfileBufferedCurveEngine->intersects( clampedPolygon.get(), &error ) )
{
std::unique_ptr< QgsAbstractGeometry > intersection( mProfileBufferedCurveEngine->intersection( clampedPolygon.get(), &error ) );
processTriangleLineIntersect( clampedPolygon.get(), intersection.get(), transformedParts, crossSectionParts );
std::unique_ptr< QgsAbstractGeometry > intersection;
intersection.reset( mProfileBufferedCurveEngine->intersection( clampedPolygon.get(), &error ) );
if ( error.isEmpty() )
{
processTriangleLineIntersect( clampedPolygon.get(), intersection.get(), transformedParts, crossSectionParts );
}
else
{
// this case may occur with vertical object as geos does not handle very well 3D data.
// Geos works in 2D from the 3D coordinates then re-add the Z values, but when 2D-from-3D objects are vertical, they are topologically incorrects!
// This piece of code is just a fix to handle this case, a better and real 3D capable library is needed (like SFCGAL).
QgsLineString *ring = qgsgeometry_cast< QgsLineString * >( clampedPolygon->exteriorRing() );
int numPoints = ring->numPoints();
QVector< double > newX( numPoints );
QVector< double > newY( numPoints );
QVector< double > newZ( numPoints );
double *outX = newX.data();
double *outY = newY.data();
double *outZ = newZ.data();
const double *inX = ring->xData();
const double *inY = ring->yData();
const double *inZ = ring->zData();
for ( int i = 0 ; ! mFeedback->isCanceled() && i < ring->numPoints() - 1; ++i )
{
*outX++ = inX[i] + i * 1.0e-9;
*outY++ = inY[i] + i * 1.0e-9;
*outZ++ = inZ[i];
}
std::unique_ptr< QgsPolygon > shiftedPoly;
shiftedPoly.reset( new QgsPolygon( new QgsLineString( newX, newY, newZ ) ) );
intersection.reset( mProfileBufferedCurveEngine->intersection( shiftedPoly.get(), &error ) );
if ( intersection.get() )
processTriangleLineIntersect( clampedPolygon.get(), intersection.get(), transformedParts, crossSectionParts );
else
QgsDebugMsgLevel( QStringLiteral( "processPolygon after shift bad geom! error: %1" ).arg( error ), 0 );
}
}
}
else // ie. polygon / line intersection ==> need tessellation
{