Some incomplete work for cleaner infill logic

lib/Slic3r/Layer/Region.pm

@@ -256,10 +256,13 @@ sub make_perimeters {
         
         # create one more offset to be used as boundary for fill
         {
+            # we offset by half the perimeter spacing (to get to the actual infill boundary)
+            # and then we offset back and forth by the infill spacing to only consider the
+            # non-collapsing regions
             my @fill_boundaries = @{union_ex([
                 Slic3r::Geometry::Clipper::offset(
                     [Slic3r::Geometry::Clipper::offset([ map @$_, @last_offsets ], -($perimeter_spacing/2 + $infill_spacing))], 
-                    +0.5*$infill_spacing,
+                    +$infill_spacing,
                 ),
             ])};
             $_->simplify(&Slic3r::SCALED_RESOLUTION) for @fill_boundaries;