Enable construction geometry

Irev-Dev commented 4 months ago

Being able to add geometry that's not officially part of a profile can be really useful, especially with constraints because it will allow a user to define a circle ahead of time, than have a line segment snap to it and follow the arc afterwards or similar.

I'm not certain of the API, but I think so that we can use the same stb function calls maybe we just do

startSketchOn('XY')
  |> startProfileAt()
  |> line()
  |> line()
  |> construction(circle())
  |> line()
  |> construction(line({from:[], to:[]}))

which will also allow for construction geometry to be sprinkled in throughout a sketch, which might be useful for when construction geometry needs to reference non-construction geometry and vise versa.

But I might change my mind and have constructionCircle, constructionLine etc (maybe draft, plan, prefab are better word candidates than construction, more concise)

This mean that the sketch group data will need to change to allow more nested data (array of arrays perhaps). In this regards it might be worth doing this issue https://github.com/KittyCAD/modeling-app/issues/1554 at the same time.

franknoirot commented 4 months ago

Just zooming in on this part of your example:

  |> line()
  |> construction(circle())
  |> line()

Will the llatter line call pick up the lines where the former left off?

Irev-Dev commented 4 months ago

I think so yes, we'll have to play it by ear, but I think that makes sense for cases where construction(circle()) want's to position itself based on previous segments in the profile, and then parts in the second half of the profile want to reference the construction circle for their geometry. I don't really see a use case for doing a profile for construction geometry i.e. chain of segments so I think this works.

I had also thought we might want to do something like

startSketchOn('XY')
  |> startProfileAt([...], %, 'profile1Tag')
  |> line()
  |> line()
  |> construction(circle())
  |> line()
  |> startProfileAt([...], %, 'profile2Tag')
  |> line()
  |> line()
  |> close()
  |> continueProfile('profile1Tag', %)
  |> line()
  |> close(%) // closing profile1

It's a little messy, so we'll see if we can avoid it, but it's an option, definitely bleeding into #1554 though.