Simple way of adding inside-anchors?

[lijon]

I'm making a box enclosure library that uses BOSL2, and would like to have anchors for the inside of the box. So that I can for example attach something relative to bottom inside center, or the bottom+left+front inside corner, etc.

What would be the best approach for this? I could add named anchors for all of them, but since named anchors can't be combined (like BOTTOM+LEFT+FRONT) I would need to add the eight corner anchors as well.

Perhaps writing a custom inside_attach() that interprets anchor vectors but offsets them so they are inside the box?

Or some better way?

[lijon]

I came up with this approach: an attachable wrapper with a dummy shape, with the size of the box inside. I can then add my inside-parts as children to box_inside() which in turn is a child to my_box(), and use the standard anchor vectors. This works fine, except from one little detail: the orientation of the anchors should be reversed, since all inside anchors points towards the center of the box, not outwards. Any idea how to achieve that?

module box_inside() {
    sz = $parent_size - [$box_side*2,$box_side*2,$box_bot+$box_top];
    position(BOTTOM)
    up($box_bot)
    attachable(BOTTOM,0,UP,size=sz) {
        union() {}; // dummy
        children();
    }
}

[adrianVmariano]

If you only want inside anchors the anchor override mechanism I think could make them.

[adrianVmariano]

Revised attach() can anchor objects inside, but you'd have to manually adjust for the box thickness.