Some of them are unecessary and should be removed from the shader instead.
But for now we need a quick fix for the crashes happening on some platforms.
See T55475.
This separate probe rendering from viewport rendering, making possible to
run the baking in another thread (non blocking and faster).
The baked lighting is saved in the blend file. Nothing needs to be
recomputed on load.
There is a few missing bits / bugs:
- Cache cannot be saved to disk as a separate file, it is saved in the DNA
for now making file larger and memory usage higher.
- Auto update only cubemaps does update the grids (bug).
- Probes cannot be updated individually (considered as dynamic).
- Light Cache cannot be (re)generated during render.
Now we light with just a user defined HDRI by default, which is useful
for material setup and texture painting and lighting without having to
set up any scene lights.
Previously it would use the scene world without lights by default, which
in some files is just black.
The calculation of the irradiance buffer was slow. Now it is only
calculated when it is being used (background_alpha > 0.0)
this solves the freeze when switching to LookDev mode.
Also changed the default calculation to use the Spherical Harmonics
calculation. This is able to generate the irradiance buffer fast, but is
less accurate. As the irradiance buffer is only used for visual
guidance speed is more important than accuracy.
Added compile directive to switch between the implementations.
(see STUDIOLIGHT_IRRADIANCE_METHOD)
Disabled caching the irradiance buffer when
STUDIOLIGHT_IRRADIANCE_METHOD_SPHERICAL_HARMONICS is used as it is not
needed.
