public void SignedAreaTest()
{
// arrange
// create a closed polygon (first point is the same as the last)
var points = new List <Coordinate>();
points.Add(new Coordinate()
{
X = 1, Y = 1
});
points.Add(new Coordinate()
{
X = 2, Y = 2
});
points.Add(new Coordinate()
{
X = 3, Y = 1
});
points.Add(new Coordinate()
{
X = 1, Y = 1
});
var polygon = new VTPolygon(points);
// act
var area = polygon.SignedArea();
// assert
// polygon is defined clock-wise so area should be negative
Assert.IsTrue(area == -1);
}
public void TestCCWPolygon()
{
var coords = TestData.GetCCWPolygon(1);
var poly = new VTPolygon(coords);
// act
var ccw = poly.IsCCW();
// assert
Assert.IsTrue(poly.SignedArea() > 0);
Assert.IsTrue(ccw);
}
public void TestCCWPolygon()
{
var coords = TestData.GetCCWPolygon(1);
var poly = new VTPolygon(coords);
// act
var ccw = poly.IsCCW();
// assert
Assert.IsTrue(poly.SignedArea() > 0);
Assert.IsTrue(ccw);
}
// docs for inner/outer rings https://www.mapbox.com/vector-tiles/specification/
public static List<List<List<Coordinate>>> Classify(List<List<Coordinate>> rings)
{
var polygons = new List<List<List<Coordinate>>>();
List<List<Coordinate>> newpoly = null;
foreach (var ring in rings)
{
var poly = new VTPolygon(ring);
if (poly.IsOuterRing())
{
newpoly = new List<List<Coordinate>>() { ring };
polygons.Add(newpoly);
}
else
{
if (newpoly != null)
{
newpoly.Add(ring);
}
}
}
return polygons;
}
