// Construct the child of "parent" with the given (i,j) index. The four
// child cells have indices of (0,0), (0,1), (1,0), (1,1), where the i and j
// indices correspond to increasing u- and v-values respectively.
public S2PaddedCell(S2PaddedCell parent, int i, int j)
{
ij_lo_ = new int[2];
Padding = parent.Padding;
Level = parent.Level + 1;
// Compute the position and orientation of the child incrementally from the
// orientation of the parent.
int pos = S2.kIJtoPos[parent.orientation_][2 * i + j];
Id = parent.Id.Child(pos);
int ij_size = S2CellId.SizeIJ(Level);
ij_lo_[0] = parent.ij_lo_[0] + i * ij_size;
ij_lo_[1] = parent.ij_lo_[1] + j * ij_size;
orientation_ = parent.orientation_ ^ S2.kPosToOrientation[pos];
// For each child, one corner of the bound is taken directly from the parent
// while the diagonally opposite corner is taken from middle().
var middle = parent.Middle;
var x = new double[] { parent.Bound[0][0], parent.Bound[0][1] };
var y = new double[] { parent.Bound[1][0], parent.Bound[1][1] };
x[1 - i] = middle[0][1 - i];
y[1 - j] = middle[1][1 - j];
Bound = new R2Rect(new R1Interval(x), new R1Interval(y));
}
private static void CompareS2CellToPadded(S2Cell cell, S2PaddedCell pcell, double padding)
{
Assert.Equal(cell.Id, pcell.Id);
Assert.Equal(cell.Level, pcell.Level);
Assert.Equal(padding, pcell.Padding);
Assert.Equal(cell.BoundUV.Expanded(padding), pcell.Bound);
var center_uv = cell.Id.CenterUV();
Assert.Equal(R2Rect.FromPoint(center_uv).Expanded(padding), pcell.Middle);
Assert.Equal(cell.Center(), pcell.GetCenter());
}
// Visits all crossings of any edge in "a_cell" with any index cell of B that
// is a descendant of "b_id". Terminates early and returns false if
// visitor_ returns false.
private bool VisitSubcellCrossings(S2ShapeIndexCell a_cell, S2CellId b_id)
{
// Test all edges of "a_cell" against the edges contained in B index cells
// that are descendants of "b_id".
GetShapeEdges(a_index_, a_cell, a_shape_edges_);
var b_root = new S2PaddedCell(b_id, 0);
foreach (var a in a_shape_edges_)
{
// Use an S2CrossingEdgeQuery starting at "b_root" to find the index cells
// of B that might contain crossing edges.
var result = b_query_.VisitCells(a.V0, a.V1, b_root, (S2ShapeIndexCell cell) =>
VisitEdgeCellCrossings(a, cell));
if (!result)
{
return(false);
}
}
return(true);
}
