How to convert from geom2 to geom3?

[t1u1]

If I have a geom2 object, how can I convert it to geom3?

From reading the docs and the code, I can think of two ways:

1. Extrusion
2. a. Convert to slice, and then b. convert slice to polygons

Since there is a bug in 2b, and since 1 uses 2 internally, both the approaches are not usable for me.

Is there any other alternative that I have missed?

FWIW, I tried converting geom2 to outlines and then constructing geom3 from it, but that doesn't give the correct result:

// This doesn't work
const g2 = subtract(rectangle({size: [5, 5]}), rectangle({size: [3, 3]}))
const o = geom2.toOutlines(g2);
// convert 2d points to 3d points
const o3 = o.map( (poly) => {
    return poly.map((p) => {
      return [...p, 0]
    })
  })
const g3 = geom3.fromPoints(o3)
return g3

With the above, the small rectangle is shown, but not the bigger one. I suspect this is not the right technique.

[z3dev]

@t1u1 Welcome!

That’s pretty much correct. 2D geometry are extruded to create special 3D geometry.

https://openjscad.xyz/dokuwiki/doku.php?id=en:design_guide_conversions

If that isn’t enough then you can extruder using custom logic to create layers between slices.

Or, you can piece together a polyhedron from points and faces.

Of course, the 3D geometry can be flat but it won’t be very useful when 3D printing, which is the focus of JSCAD.

[t1u1]

Indeed, I am using JSCAD so that I can 3D print the designs. But I am stuck because of the bug in #907

I thought I would workaround the issue by creating end caps manually, but looks like that is not possible, because it eventually hits the same bug!

Is there a chance that the bug gets fixed in the near future? Otherwise, I will be forced to rewrite everything using another library, although I like JSCAD so far.

[z3dev]

@t1u1 that bug has been fixed by @platypii
Please try again

[t1u1]

Indeed, everything is working fine now. Thanks @z3dev @platypii