Function precisePredicates

source/MRMesh/MR2DContoursTriangulation.cpp:87–130

default predicates: exact integer arithmetic with simulation-of-simplicity (historical behavior)

// default predicates: exact integer arithmetic with simulation-of-simplicity (historical behavior)
static SweepLinePredicates precisePredicates( const Contours2f& contours )
{
    Box3f box;
    int pointsSize = 0;
    for ( const auto& cont : contours )
    {
        for ( const auto& p : cont )
            box.include( to3dim( p ) );
        if ( cont.size() > 3 )
        {
            assert( cont.front() == cont.back() );
            pointsSize += int( cont.size() ) - 1;
        }
    }

    auto pts = std::make_shared<Vector<Vector2i, VertId>>();
    pts->reserve( pointsSize );
    auto toInt = [conv = getToIntConverter( Box3d( box ) )] ( const Vector2f& coord )
    {
        return to2dim( conv( to3dim( coord ) ) );
    };
    auto toFloat = [conv = getToFloatConverter( Box3d( box ) )] ( const Vector2i& coord )
    {
        return to2dim( conv( to3dim( coord ) ) );
    };

    SweepLinePredicates p;
    setPts2Predicates( p, pts );
    // resolve an input vertex by (contourId, pointId); initMeshByContours_ drives the order, so
    // `contours` only needs to outlive construction (every caller passes its own input by reference)
    p.addInputPoint = [&contours, pts, toInt] ( VertId v, int contourId, int pointId )
    {
        pts->autoResizeSet( v, toInt( contours[contourId][pointId] ) );
    };
    p.addIntersectionPoint = [pts] ( VertId v, VertId a, VertId b, VertId c, VertId d )
    {
        pts->autoResizeSet( v, findSegmentSegmentIntersectionPrecise( ( *pts )[a], ( *pts )[b], ( *pts )[c], ( *pts )[d] ) );
    };
    p.point = [pts, toFloat] ( VertId v )
    {
        return to3dim( toFloat( ( *pts )[v] ) );
    };
    return p;
}

// per-contour vertex counts; lets the queue build the initial edge loops independently of coordinate dimension
static std::vector<int> getContourSizes( const Contours2f& contours )