Union question

[Shortyoo]

Regarding: #489

Took a while to spot my mistake. The parameters passed are actually those right here:
Union.txt
As said, it worked in v1.0.3 but doesn't work now.
Though when I multiply the values with 1000 and try it again, it gives me the result I expect.

[AngusJohnson]

So what's the question?
It seems that something isn't working as you're expecting,
However, you haven't explained why the results you're getting are wrong.
And it really helps if you also provide some (very simple) code to demonstrate how you're using the library.

[Shortyoo]

The question:
Why is v1.2.0 behaving differently compared to v1.0.3.
The result I'm expecting is the union of those 2 which should imo be possible to build.

Drawing the polygons shows the result I expect (and got in v1.0.3):

(The green polygon has a visual bug in there - please ignore that)

Yet sol (see sample-code) contains the polygons I initially passed.

Sample-code:

PathsD subj = new PathsD(), sol = new PathsD();

      subj.Add(Clipper.MakePath(new double[] { 4.69937028509979 , 6.12422883958625,
        4.64402725087668 , 6.1242414645803,
        4.64401600621849 , 6.07495219020654,
        5.17070767409552 , 5.70234459887655,
        5.29575632904683 , 5.70231601844938 }));

      subj.Add(Clipper.MakePath(new double[] { 4.6440361623322 , 6.16330605511392,
        4.64402725087668 , 6.1242414645803,
        4.69937028509979 , 6.12422883958625}));

      sol = Clipper.Union(subj, null, FillRule.EvenOdd, 5);

Why the result is wrong:
I expected the merged polygon of those 2 passed.

[AngusJohnson]

OK, I understand the problem now.
And while the solution isn't strictly wrong, I agree that the union op should merge these polygons.
I know why this is happening and I think this can be fixed fairly easily.

[AngusJohnson]

In Clipper.Engine.cs;

~ line 2350

    private void CheckJoinLeft(Active e,
      Point64 pt, bool checkCurrX = false)
    {
      Active? prev = e.prevInAEL;
      if (prev == null || IsOpen(e) || IsOpen(prev) ||
        !IsHotEdge(e) || !IsHotEdge(prev)) return;
      if ((pt.Y < e.top.Y + 2 || pt.Y < prev.top.Y + 2) && // avoid trivial joins
        ((e.bot.Y > pt.Y) || (prev.bot.Y > pt.Y))) return;
      ....

~ line 2377

    private void CheckJoinRight(Active e, 
      Point64 pt, bool checkCurrX = false)
    {
      Active? next = e.nextInAEL;
      if (IsOpen(e) || !IsHotEdge(e) || IsJoined(e) ||
        next == null || IsOpen(next) || !IsHotEdge(next)) return; 
      if ((pt.Y < e.top.Y + 2 || pt.Y < next.top.Y + 2) && // avoid trivial joins
        ((e.bot.Y > pt.Y) || (next.bot.Y > pt.Y)))  return;
      ....

[Shortyoo]

Thanks for your response!
I assume it's going to work as I expect in a future update?
Since I use the nuget-package, I cant edit the code on my own.

[AngusJohnson]

I assume it's going to work as I expect in a future update?

That's the plan 😁.

Since I use the nuget-package, I cant edit the code on my own.

Well you'll probably have to wait a while since I'm unlikely to update it very soon.