private VerticalPrismalSurface CreateSurface(bool isClosedBase = false, bool isClosedSurface = false, bool isCounterclockwise = true)
{
var baseVertices = new List <Vector2>
{
new Vector2(1.1, 2.2),
new Vector2(3.5, -5.3),
new Vector2(-7.8, 9.1),
new Vector2(-1.8, 0.1),
new Vector2(3.8, 6.1)
};
IPolyline @base;
if (isClosedBase)
{
var line = new ClosedPolyline(baseVertices);
@base = line.SignedArea() > 0 ^ isCounterclockwise ? line : line.AsReverse();
}
else
{
@base = new OpenPolyline(baseVertices);
}
var zRange = new Interval(-3.14, 2.88);
return(new VerticalPrismalSurface(@base, zRange, isClosedSurface));
}
public void ClosedPolyline_SignedArea_is_correct_for_horizontal_triangle()
{
var x = -0.13;
var y = 3.14;
var a = 1.44;
var h = 2.72;
IEnumerable <Vector2> triangleVertices = new List <Vector2>
{
new Vector2(x, y),
new Vector2(5.555, y + h),
new Vector2(x + a, y)
};
var area = a * h / 2;
var negativeTriangle = new ClosedPolyline(triangleVertices.ToList());
Expect(negativeTriangle.SignedArea(), Is.EqualTo(-area).Within(_tolerance));
var positiveTriangle = new ClosedPolyline(triangleVertices.Reverse().ToList());
Expect(positiveTriangle.SignedArea(), Is.EqualTo(area).Within(_tolerance));
}