Possible bug: suspicious looking if-statement

[djcimco]

Hi

I have a program that doesn't yield the z-values i expected. Debugging it, i came across this at line 1948 in clipper.engine.cpp:

#ifdef USINGZ
  if (pt.z)   // This looks suspicious. If i comment this out, i get the results i expect.
  if (zCallback_ && resultOp) SetZ(e1, e2, resultOp->pt);
#endif

The first if statement evaluates the value pt.z, not if pt.z exists. But since z values default to 0, this check is always false. The formatting of this code looks off, if it was intentional i would assume it too look like this:

#ifdef USINGZ
if (pt.z && zCallback_ && resultOp) SetZ(e1, e2, resultOp->pt);
#endif

Is this really the intended behavior, or is it an error?

Here's the code i'm running. This correctly creates 2 new points at (5,5) and (5,-5), but the z values i would expect to be 1 and 2, are instead 0 and 1:

  PathsD shapes{
    PathD{{0,-10, 1}, {10,0, 1}, {0,10, 1}},
    PathD{{5,-10, 2}, {15,0, 2}, {5,10, 2}}
  };

  PathsD solutions1;
  Clipper2Lib::ClipperD clipper(DecimalPrecision());
  auto callback = [](const PointD& subjectP1, const PointD& subjectP2, const PointD& clipP1, const PointD& clipP2, PointD& newPoint)
    {
      newPoint.z = clipP2.z;
    };
  clipper.SetZCallback(callback);
  clipper.PreserveCollinear(false);
  clipper.AddSubject(shapes);
  clipper.Execute(Clipper2Lib::ClipType::Union, Clipper2Lib::FillRule::NonZero, solutions1);

[AngusJohnson]

Perhaps you've inadvertently corrupted the code as this bug isn't present here:

Clipper2/CPP/Clipper2Lib/src/clipper.engine.cpp

Lines 1948 to 1950 in c86619c

	#ifdef USINGZ
	resultOp = AddLocalMaxPoly(e1, e2, pt);
	if (zCallback_ && resultOp) SetZ(e1, e2, resultOp->pt);

[djcimco]

You're right, i'm so embarassed.. Thanks for the library, it's really great.