public virtual void TestArea()
{
double radius = DistanceUtils.EARTH_MEAN_RADIUS_KM * DistanceUtils.KM_TO_DEG;
//surface of a sphere is 4 * pi * r^2
double earthArea = 4 * Math.PI * radius * radius;
ICircle c = ctx.MakeCircle(random.Next(-180, 180), random.Next(-90, 90),
180); //180 means whole earth
CustomAssert.EqualWithDelta(earthArea, c.GetArea(ctx), 1.0);
CustomAssert.EqualWithDelta(earthArea, ctx.WorldBounds.GetArea(ctx), 1.0);
//now check half earth
ICircle cHalf = ctx.MakeCircle(c.Center, 90);
CustomAssert.EqualWithDelta(earthArea / 2, cHalf.GetArea(ctx), 1.0);
//circle with same radius at +20 lat with one at -20 lat should have same area as well as bbox with same area
ICircle c2 = ctx.MakeCircle(c.Center, 30);
ICircle c3 = ctx.MakeCircle(c.Center.X, 20, 30);
CustomAssert.EqualWithDelta(c2.GetArea(ctx), c3.GetArea(ctx), 0.01);
ICircle c3Opposite = ctx.MakeCircle(c.Center.X, -20, 30);
CustomAssert.EqualWithDelta(c3.GetArea(ctx), c3Opposite.GetArea(ctx), 0.01);
CustomAssert.EqualWithDelta(c3.BoundingBox.GetArea(ctx), c3Opposite.BoundingBox.GetArea(ctx), 0.01);
//small shapes near the equator should have similar areas to euclidean rectangle
IRectangle smallRect = ctx.MakeRectangle(0, 1, 0, 1);
CustomAssert.EqualWithDelta(1.0, smallRect.GetArea(null), 0.0);
double smallDelta = smallRect.GetArea(null) - smallRect.GetArea(ctx);
Assert.True(smallDelta > 0 && smallDelta < 0.0001);
ICircle smallCircle = ctx.MakeCircle(0, 0, 1);
smallDelta = smallCircle.GetArea(null) - smallCircle.GetArea(ctx);
Assert.True(smallDelta > 0 && smallDelta < 0.0001);
//bigger, but still fairly similar
//c2 = ctx.makeCircle(c.getCenter(), 30);
double areaRatio = c2.GetArea(null) / c2.GetArea(ctx);
Assert.True(areaRatio > 1 && areaRatio < 1.1);
}
public override double Area(ICircle circle)
{
return(circle.GetArea(null));
}