Lucas Givord authored Aug 16, 2023 and Mathieu Westphal (Kitware) committed Aug 18, 2023

When we didn't set light, we take in account the ambient of
the default light which is always black, so when we activate
the ShadeOn() the ambient will always be equal to 0.

Now, like for a single volume, we didn't use the ambient light in such
context.