I am trying to understand Panda’s default lighting.
If you don’t set explicit lights, some are created internally (otherwise your scene would be completely dark). What I am looking for is a detailed description of under what conditions these lights are created, their attributes, and how to turn them off. (And ideally a pointer to the code that does it.) This is not documented in the most relevant manual page:
It does say “The default directional light is shining down the forward (+Y) axis”, but the context suggests it’s talking about the default attributes of a DirectionalLight you create, not about the lights that exist if you create nothing.
Experiments suggest that the nature of the default lights depends on how many other lights you create and/or their types. If I create no lights, cubes are lit on at least 5 faces, whereas if I create a very dim directional and ambient light, cubes are only lit on 3 faces (presumably by the remaining default light alone). Nothing I tried so far has completely turned off default lighting.
Besides the types and parameters of the default lights, it’s important to understand at what point and for what objects the decision is made to use them, e.g. per-node, per-DisplayArea, per-camera, etc.
(I am willing to document this in the manual once I find out definitive-enough info to document it correctly.)