Adding an outline to ScenegraphLayer's rendered models

[vgrafe]

Hi all,

I've been trying this for hours and it is time to ask around. I am trying to subclass ScenegraphLayer to render models with two extra features:

• apply a color filter to the rendered model (no problem here)
• add an outline around the model, with width/color configurable

The latter is proving difficult. I think the idea is to render models in two passes: the first pass renders an inflated version of the model, painted in the outline color. "inflated" and not scaled/sized up so it really look like an outline and not a shadow - if I am right, that part requires to inject vs:DECKGL_FILTER_GL_POSITION and displace vertices along normals.

That is (I think) what I am doing wrong: both passes always draw models with the exact same size (verified when applying different colors and commenting out either pass in the draw method), so the outline is not shown.

This is while using deckgl 9.0.

I hope this makes sense - would love to know if there's an other approach to solving this, otherwise this can probably be solved by fixing the vs:DECKGL_FILTER_GL_POSITION hook.

Here's an sandbox in hopes it helps.

I could only troubleshoot by commenting/uncommenting vs:DECKGL_FILTER_GL_POSITION and the line 122, model.draw(renderPass);, in OutlineLayer.ts.

Appreciate any help on this!