Separate Component from world_coords

Should parts have a separate class instance for its world presence?

Current Implementation

>>> from cqparts_misc.basic.primatives import Cube
>>> from cqparts.utils import CoordSystem

>>> cube = Cube()
>>> cube.local_obj  # geometry in the part's native coordinate system

>>> cube.world_coords = CoordSystem((1, 2, 3))
>>> cube.world_obj  # geometry translated by (1, 2, 3)

Potentially changed to

>>> from cqparts_misc.basic.primatives import Cube
>>> from cqparts.utils import CoordSystem
>>> from cqparts import WorldPart

>>> cube = Cube()
>>> cube.obj  # geometry in the part's native coordinate system

>>> world_cube = WorldPart(cube)
>>> world_cube.coord_sys = CoordSystem((1, 2, 3))
>>> world_cube.obj  # geometry translated by (1, 2, 3)

As suggested by @gntech @zwn in https://github.com/fragmuffin/cqparts/issues/97#issuecomment-394616079

[zwn]

Well, I am thinking about a system where the actual position and orientation of Parts is completely external to them. In such a system the pose of a Part would only be part of its containing Assembly and it would be based on CoordinateSystem of the containing Assembly. Such an Assembly could itself be easily placed within another Assembly just as Part can be. The top level Assembly CoordinateSystem would be the world coordinates. Actually just like a scene graph.

[fragmuffin]

@zignig

if the coordinates inside a assembly are localised, would it mean that the Fasteners and some of the make_alterations would not need the world to local and back again flipping for the calculations

yeah!, I think these calculations would be less fiddly. But only if we have a clean and intuitive way of getting CoordSystem instances from solved assemblies.

I’ve been pondering how to auto explode assemblies, as they get more levels this becomes increasingly important, and it looks so cool. 😉

It would also make exploding a simpler process… one way to do it would be to recursively offset assemblies and parts by a factor along their local Z axis. It would look cool! and I think that’s important… cadquery and cqparts as tools are still being adopted by the larger community, and visual appeal is a big part of that.