A light-ambient factor is more complicated because the light radius and the light position is affecting it, and I need to check if the fixed pipeline can support it in a consistent way.

There is a plan to add directional light, but it's not yet implemented in the renderer,
(mainly because of the shadow system, still not sure of the technique to use, perspective shadow buffer or other).

I don't have plans for ambient light, I usually prefer using the material emit, or an emit texture.
But an "ambient" variable can be added very easily in the light property, it will just need some homework first
to know how to do a consistent result between fixed pipeline and shading pipeline.

An ambient light factor (vec3) on the scene properties could work well right? Then use that factor for light calculations in both fixed and shader pipelines.

I don't have plans for ambient light, I usually prefer using the material emit, or an emit texture.
But an "ambient" variable can be added very easily in the light property, it will just need some homework first
to know how to do a consistent result between fixed pipeline and shading pipeline.

Thanks,
- Ricardo