Function polylineOffset

source/MRMesh/MRDistanceMap.cpp:1376–1415

}

Polyline2 polylineOffset( const Polyline2& polyline, float pixelSize, float offset )
{
    MR_TIMER;

    assert( offset > 0.f );

    const auto box = polyline.computeBoundingBox();
    const auto size = box.size();

    const auto padding = offset + 2 * pixelSize;

    ContourToDistanceMapParams params;
    params.pixelSize = {
        pixelSize,
        pixelSize,
    };
    params.resolution = {
        int( ( size.x + 2 * padding ) / pixelSize ),
        int( ( size.y + 2 * padding ) / pixelSize ),
    };
    params.orgPoint = {
        box.min.x - padding,
        box.min.y - padding,
    };

    ContoursDistanceMapOptions options;
    //compute precise distances only in the cells crossed by offset-isoline
    options.maxDist = offset + pixelSize;
    options.minDist = std::max( offset - pixelSize, 0.0f );

    const auto distanceMap = distanceMapFromContours( polyline, params, options );

    auto isoline = distanceMapTo2DIsoPolyline( distanceMap, offset );

    AffineXf3f xf( params );
    for ( auto& p : isoline.points )
        p = Vector2f( xf( { p.x, p.y, 0 } ) );

    return isoline;
}

} //namespace MR