union bug, or am I doing something wrong?

[microcan]

I have a simple, closed, CCW triangle, that when I union with itself, I get an empty result, rather than the the same triangle, as I would expect. With slightly different vertices, I do get the expected result. I just wanted to make sure I was using the code correctly first.

Here is a test that fails when I expect it to pass. The results.Count is zero:

    public void ClipperSimpleUnionTestFails()
    {
      Path64 poly1 = Clipper.MakePath(new int[] { 0, 0, 3, 0, 1, 1, 0, 0 });
      Path64 poly2 = Clipper.MakePath(new int[] { 0, 0, 3, 0, 1, 1, 0, 0 });

      Clipper64 c64 = new Clipper64();

      c64.AddSubject(poly1);
      c64.AddSubject(poly2);

      Paths64 results = new Paths64();
      Paths64 resultsOpen = new Paths64();

      c64.Execute(ClipType.Union, FillRule.Positive, results, resultsOpen);

      Assert.IsTrue(results.Count > 0);
      Assert.IsTrue(Clipper.Area(results[0]) == Clipper.Area(poly1));
    } 

However, if I uses these coordinates, the test passes:

      Path64 poly1 = Clipper.MakePath(new int[] { 0, 0, 3, 0, 2, 2, 0, 0 });
      Path64 poly2 = Clipper.MakePath(new int[] { 0, 0, 3, 0, 2, 2, 0, 0 });

Also, point sets like scaling of the failing test will pass:

{ 0, 0, 300, 0, 100, 100, 0, 0}

[AngusJohnson]

Also, point sets like scaling of the failing test will pass

As expected.
You need to scale appropriately to accommodate for rounding.

[microcan]

Aah, makes perfect sense. If using int, I need to make sure the sets of points are spanning a sufficient range in int space.