Add Gap Fill on thin empty surfaces

[raidolo]

Version

2.3.55.5

Operating system type + version

Windows 10 1809

3D printer brand / version + firmware version (if known)

Not relevant

Behavior

Gap Fill is not done if the Solid Infill Area Threshold is lower than the default value (70)
If I set the Solid Infill Area Threshold to 1, the layer has the standard infill, but there's no gap fill where it "should" be.
Instead SS tries to use the infill also in the gap, and depending on what infill is in use, the part looks more or less filled.

• Expected Results
  

• Actual Results

Project File (.3MF) where problem occurs

It's a benchy :) but still...here it is....

3DBenchy.zip

[supermerill]

In the first pic, it's the gap fill from the solid infill (because you have rectilinear with gapfill, if you use only rectilinear, you won't have a gapfill either).
If you only want 2 perimeters, no need to add more gapfill in-between because the expected wall width is already achieved.

If you don't want a solid layer (that's why you reduced the 'Solid Infill Area Threshold', right?), I don't see what is wrong on the second pic: it has 2 perimeters and a sparse infill

[raidolo]

I want two perimeters but not completely empty walls, if there's not enough space to create a sparse infill, then I think it's best to do a gap fill, like Prusa Slicer does. It just does gap fill there and the sparse infill on the front area.

[supermerill]

that's a new feature, with a new gap-fill threshold.