Add a default value input for geomcolor

[crydalch]

It would be nice if Geometry Color could specify a default value, so that users can choose what color to provide when the geometry property is missing.

Currently, many people just use Geom Prop Value, because you can specify the default color.

Thanks!

[crydalch]

Would there be a problem with geomcolor adding a default input, but have it default to 0,0,0 (like it currently seems to do)?

[jstone-lucasfilm]

That sounds very reasonable to me, @crydalch, and I'm CC'ing @dbsmythe for his thoughts. Here are the current interfaces for geomcolor, where the default zero values are hardcoded in the output elements:

https://github.com/AcademySoftwareFoundation/MaterialX/blob/main/libraries/stdlib/stdlib_defs.mtlx#L1277

[kwokcb]

There is this related Slack thread started by @hybridherbst which encompasses geomprop: https://academysoftwarefdn.slack.com/archives/C02HJH53RN3/p1705501236612989

[hybridherbst]

I think

• vertex color could also default to (1,1,1) (that's what it does in other formats/renderers), since a common usage is baseColor = baseColorFactor * baseColorMap * vertexColor
• uv should default to (0,0)
• normal should default to something calculated if it isn't provided probably