Line art uses `DEG_OBJECT_ITER_BEGIN` to load all objects that has a
geometry in the scene, which is kind of a hack since the beginning. This
left potential problem where the iterator could go through some objects
that line art didn't have a dependency on (e.g. other grease pencil
objects):
- Since those "other" objects often evaluates fast enough, so
line art always end up having valid data from everywhere after lengthy
mesh evaluation prior to itself, so this problem was not prominent.
- However, in rare cases, there are other objects that takes a lot of
time to evaluate, this causes line art to potentially iterate to objects
that are still invalid.
This fix will build a `Vector<Object *>` during `update_depsgraph`, and
use such list inside `DEGObjectIterSettings` to filter out objects that
the modifier isn't dependent on, thus remove the possibility of reading
objects that hasn't been evaluated.
Since Line art will not add grease pencil objects as potential geometry
inputs, all mesh/curve types of geometries generated by geometry nodes
modifier directly inside other grease pencil objects won't be loaded.
This can be mitigated by having a third mesh object that reads the
result from the grease pencil object that generates geometries, then
directly output them for line art to read.
This also fixes#128888.
Pull Request: https://projects.blender.org/blender/blender/pulls/128890
9cb4d3bbff