Option to render retractions

[sophiedeziel]

I had that idea after investigating stringing issues that fused parts of a print-in-place flexible model.

Prusa Slicer has the option of rendering retractions. It's useful to be able to render that.

For this feature to be as accurate as possible, we'd have to implement the G0/G1 with negative E case as well as introducing G10 support.

The API could be very similar to what we have right now with the other types of renders:

{
  ...,
  renderRetractions: true,
  retractionColor: '#FF0000',
}

• detect retractions in g0/g1 movements: movements with E < 0
• detect firmware retractions using G10/G11 (I think G22/G23 too and possibly other vendor-specific gcodes)

[remcoder]

Can I suggest we do this in v3.1+?

[sophiedeziel]

Yes!

[remcoder]

I just realized PR #269 actually detects and counts retractions now.

atm, zero-length movements are removed from the scene because they would be invisible anyway. But they might as well be rendered and the interpreter at least detects them.

[sophiedeziel]

There's also the native G10 gcode, but I think slicers mostly use g0/g1 for backward compatibility with older printer firmware.

[remcoder]

Good point. I updated the description