The cache mechanism for line art is changed during migration to GPv3,
however the code path failed to handle following cases which could lead
to a few problems:
- Line art cache isn't deleted after last line art modifier because it
coule be hidden, causing memory leaks.
- A modifier inside a multiple line art modifier sequence that doesn't
use cache would prematurely delete line art cache, causing subsequent
line art modifier to give empty result.
- When the first line art modifier is hidden (in viewport/render), the
cache is not created correctly, leading to crashes.
Now the new code logic addresses these problems properly by:
- Making sure the last visible line art modifier deletes cache.
- Giving a fresh cache pointer for modifiers that doesn't use global
cache.
- Line art cache is correctly ensured when there are modifiers that
are hidden
Pull Request: https://projects.blender.org/blender/blender/pulls/129953
2e82f95237