WIP: Fix #113377: Pass edit mesh pointer through modifiers #120999

Hans Goudey · 2024-04-23T22:14:10+02:00

Hans Goudey commented

2024-04-23 22:14:10 +02:00

Propagate the edit mesh pointers through copied meshes in modifiers
and geometry nodes instead of just setting the edit mesh pointer at the
end of the modifier stack. This means we have the ability to detect when
the mesh is completely replaced by the mesh from another object during
evaluation. Then we can either skip mapped data extraction or skip edit
mode drawing completely.

The other benefit is removing the need to write to the evaluated mesh,
which means it can be shared directly among evaluated objects, which
is currently the only simple way to avoid uploading duplicate data to the
GPU, which can be an important optimization. It also simplifies the mesh
modifier stack.

TODO:

Decide what the behavior should be. Should we try to just skip mapping with original indices, or should we use a simpler approach and just skip drawing the mesh as if it's in edit mode?
Figure out if accessing the original object is wrong. I heard it might be, but the edit mesh itself is all original data too. So if it's wrong, then the whole existing design is wrong too!

Propagate the edit mesh pointers through copied meshes in modifiers and geometry nodes instead of just setting the edit mesh pointer at the end of the modifier stack. This means we have the ability to detect when the mesh is completely replaced by the mesh from another object during evaluation. Then we can either skip mapped data extraction or skip edit mode drawing completely. The other benefit is removing the need to write to the evaluated mesh, which means it can be shared directly among evaluated objects, which is currently the only simple way to avoid uploading duplicate data to the GPU, which can be an important optimization. It also simplifies the mesh modifier stack. --- TODO: - Decide what the behavior should be. Should we try to just skip mapping with original indices, or should we use a simpler approach and just skip drawing the mesh as if it's in edit mode? - Figure out if accessing the original object is wrong. I heard it might be, but the edit mesh itself is all original data too. So if it's wrong, then the whole existing design is wrong too!

Hans Goudey added 12 commits 2024-04-23 22:14:19 +02:00

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a2b0628521 Mesh: Store BMEditMesh in shared pointer

The main motivation for this is that it's part of a fix for #113377,
where I want to propagate the edit mesh pointers through copied mesh
in the modifier stack and geometry nodes, instead of just setting the
mesh's edit mesh pointer at the end of the modifier stack. That would
have two main benefits:
1. We avoid the need to write to the evaluated mesh, which means it
   can be shared directly among evaluated objects.
2. When an object's mesh is completely replaced by the mesh from another
   object during evaluation (with the object info node), the final edit
   mesh pointer will not be incorrect, allowing us to skip index-mapped
   GPU data extraction.

Beyond that, using a shared pointer just makes things more automatic.
Handling of edit mesh data is already complicated enough, this way some
of the worry and complexity can be handled by RAII.

One thing to keep in mind is that the edit mesh's BMesh is still freed
manually with `EDBM_mesh_free_data` when leaving edit mode. I figured
that was a more conservative approach for now. Maybe eventually that
could be handled automatically with RAII too.

53dd169209 Fix #113377 : Track edit mesh pointer through modifiers

cd434c09fa Merge branch 'main' into fix-mesh-edit-mapped-extract-edit-mesh

cbfbe14f7b Progress

310c0f6728 Cleanup

b8cb68d1c2 Merge branch 'main' into fix-mesh-edit-mapped-extract-edit-mesh

d64d4fdb9f Cleanup

517f895b48 Fix

a186bfcf1d Progress

8d9f7dbbd5 Merge branch 'main' into fix-mesh-edit-mapped-extract-edit-mesh

5ff6d32d5f Cleanup

03b5836d33 Progress

Hans Goudey changed title from ~~WIP: Fix #113377: Track edit mesh pointer through modifiers~~ to WIP: Fix #113377: Pass edit mesh pointer through modifiers

2024-04-24 02:01:28 +02:00

This pull request is marked as a work in progress.

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WIP: Fix #113377: Pass edit mesh pointer through modifiers #120999

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