stem_inset is cutting off the bottom of the keycap outer profile

[edwardbrowncross]

What version of OpenSCAD are you on?

2025.02.07 (+Manifold)

Describe the bug

Keys with positive $stem_inset (e.g OEM, ASA) seem to be hovering above the x-y plane. I believe they are not translated, but rather missing the bottom of the outer profile, which currently ends where the stem does. If I understand this parameter correctly, the keycap should continue past the end of the stem

Setting the inset to 0 makes the keycap lengthen to reach the x-y plane (and the stem along with it).

To Reproduce

Render key_profile("asa", 1) key();

Compare This with key_profile("asa", 1) inset(0) key();

[edwardbrowncross]

The behaviour changes to what I expect if I remove the $stem_inset from the dished module in src/key.scad:

module dished(depth_difference = 0, inverted = false) {
  intersection() {
    children();
    difference(){
      union() {
        // envelope is needed to "fill in" the rest of the keycap. intersections with small objects are much faster than differences with large objects
-       envelope(depth_difference, $stem_inset);
+       envelope(depth_difference);
        if (inverted) top_placement(depth_difference) color($secondary_color) _dish(inverted);
      }
      if (!inverted) top_placement(depth_difference) color($secondary_color) _dish(inverted);
      // %top_placement(depth_difference) _dish();
    }
  }
}

But I don't understand the code enough to say whether this is correct or what the side-effects might be