Comment by phkahler

>> Being an ex professional CAD person I think PBR is the wrong visual style for most cad though. The main point of shading is to improve the perception of shape and part isolation there. Traditional airbrush based engineering illustration styles are much better reference. So something like Gooch with depth buffer unsharp masking IMHO would be much much more appropriate.

That is some excellent feedback. I like that our current simple Snells law shader doesn't add specular highlights and can do flat shading by turning off all but the ambient light. I had never heard of "Gooch" and I don't recommend searching for it without "Gooch in the context of rendering". That looks interesting and we already have code to draw the silhouette edges.

I do think adding a PBR based Fresnel component with a backlight gives a similar but less sharp delineation of edges of objects, but it tends toward white right on the edge.

While people like a good PBR render, I agree that in CAD the objective of the rendering is to clearly convey the geometry AND the sketching tools and entities the user is manipulating.