Manifold surface cover when using small offsets

[UBaer21]

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Environment
v2024.02.22 on Windows

Issue
offset(-.0001) produces a face covering the surface of the difference when rendering

code:

size=60; // only on larger sizes
matrixString=[for(i=[0:size^2]) round(rands(0,1,1,i)[0]) ];
module qrCodePattern(matrixString=matrixString, dimension=size) {
    translate([1,1,-1])linear_extrude(2,convexity=5)offset(-.0001)union(){
        for (y = [0 : dimension-1]) {
            for (x = [0 : dimension-1]) {
                if (str(matrixString[y * dimension + x]) == "1") {
                    translate([x , (dimension - 1 - y) , 0]) square(1, center = true);
                }
            }
        }
    }
}

  difference(){
    cube(size+1);
    color("navy")qrCodePattern();
  }

preview looks fine

render

[kintel]

Reproducible on latest master on macOS as well.

@pca006132 Any ideas? I've seen similar things when playing around with Manifold's 2D triangulator, but I haven't tried to diagnose this yet.

[pca006132]

sounds like a bug in the triangulator. is it possible to get a minimal example?

[kintel]

It seems tricky to trigger this on a minimal example, but I'll dig around a bit.

[kintel]

Some observations:
If you replace the last construct with any of these, it works:

difference() {
  translate([0,0,-size-1]) cube(size+1);
  color("navy")qrCodePattern();
}

difference() {
  cube(size+1);
  translate([0,0,size+1]) color("navy")qrCodePattern();
}

Also, both union and intersection work where difference fails.