// Verifies that an arbitrary S2ShapeIndex is buffered correctly, by first
// converting the covering to an S2Polygon and then checking that (a) the
// S2Polygon contains the original geometry and (b) the distance between the
// original geometry and the boundary of the S2Polygon is at least "radius".
//
// The "radius" parameter is an S1Angle for convenience.
// TODO(ericv): Add Degrees, Radians, etc, methods to S1ChordAngle?
private static void TestBufferIndex(string index_str, S1Angle radius_angle, S2RegionCoverer coverer)
{
var index = MakeIndexOrDie(index_str);
S1ChordAngle radius = new(radius_angle);
var region = new S2ShapeIndexBufferedRegion(index, radius);
S2CellUnion covering = coverer.GetCovering(region);
// Compute an S2Polygon representing the union of the cells in the covering.
S2Polygon covering_polygon = new();
covering_polygon.InitToCellUnionBorder(covering);
MutableS2ShapeIndex covering_index = new();
covering_index.Add(new S2Polygon.Shape(covering_polygon));
// (a) Check that the covering contains the original index.
Assert.True(S2BooleanOperation.Contains(covering_index, index));
// (b) Check that the distance between the boundary of the covering and the
// the original indexed geometry is at least "radius".
S2ClosestEdgeQuery query = new(covering_index);
query.Options_.IncludeInteriors = (false);
var target = new S2ClosestEdgeQuery.ShapeIndexTarget(index);
Assert.False(query.IsDistanceLess(target, radius));
}
public void Test_S2ShapeIndexBufferedRegion_EmptyIndex()
{
// Test buffering an empty S2ShapeIndex.
var index = new MutableS2ShapeIndex();
var radius = new S1ChordAngle(S1Angle.FromDegrees(2));
var region = new S2ShapeIndexBufferedRegion(index, radius);
var coverer = new S2RegionCoverer();
S2CellUnion covering = coverer.GetCovering(region);
Assert.True(covering.IsEmpty());
}
public void Test_S2ShapeIndexBufferedRegion_PointZeroRadius()
{
// Test that buffering a point using a zero radius produces a non-empty
// covering. (This requires using "less than or equal to" distance tests.)
var index = MakeIndexOrDie("34:25 # #");
var region = new S2ShapeIndexBufferedRegion(index, S1ChordAngle.Zero);
var coverer = new S2RegionCoverer();
S2CellUnion covering = coverer.GetCovering(region);
Assert.Equal(1, covering.Size());
foreach (S2CellId id in covering)
{
Assert.True(id.IsLeaf());
}
}
public void Test_S2ShapeIndexBufferedRegion_FullPolygon()
{
// Test buffering an S2ShapeIndex that contains a full polygon.
var index = MakeIndexOrDie("# # full");
var radius = new S1ChordAngle(S1Angle.FromDegrees(2));
var region = new S2ShapeIndexBufferedRegion(index, radius);
var coverer = new S2RegionCoverer();
S2CellUnion covering = coverer.GetCovering(region);
Assert.Equal(6, covering.Size());
foreach (S2CellId id in covering)
{
Assert.True(id.IsFace());
}
}
public void Test_S2ShapeIndexBufferedRegion_BufferedPointVsCap()
{
// Compute an S2Cell covering of a buffered S2Point, then make sure that the
// covering is equivalent to the corresponding S2Cap.
var index = MakeIndexOrDie("3:5 # #");
S2Point point = MakePointOrDie("3:5");
var radius = new S1ChordAngle(S1Angle.FromDegrees(2));
var region = new S2ShapeIndexBufferedRegion(index, radius);
S2RegionCoverer coverer = new();
coverer.Options_.MaxCells = 50;
S2CellUnion covering = coverer.GetCovering(region);
S2Cap equivalent_cap = new(point, radius);
S2Testing.CheckCovering(equivalent_cap, covering, true);
}
public void Test_S2ShapeIndexBufferedRegion_FullAfterBuffering()
{
// Test a region that becomes the full polygon after buffering.
var index = MakeIndexOrDie("0:0 | 0:90 | 0:180 | 0:-90 | 90:0 | -90:0 # #");
var radius = new S1ChordAngle(S1Angle.FromDegrees(60));
var region = new S2ShapeIndexBufferedRegion(index, radius);
var coverer = new S2RegionCoverer();
coverer.Options_.MaxCells = 1000;
S2CellUnion covering = coverer.GetCovering(region);
Assert.Equal(6, covering.Size());
foreach (S2CellId id in covering)
{
Assert.True(id.IsFace());
}
}