Subdivision surface efficiency relies on caching pre-computed topology
data for evaluation between frames. However, while eed45d2a23
introduced a second GPU subdiv evaluator type, it still only kept
one slot for caching this runtime data per mesh.
The result is that if the mesh is also needed on CPU, for instance
due to a modifier on a different object (e.g. shrinkwrap), the two
evaluators are used at the same time and fight over the single slot.
This causes the topology data to be discarded and recomputed twice
per frame.
Since avoiding duplicate evaluation is a complex task, this fix
simply adds a second separate cache slot for the GPU data, so that
the cost is simply running subdivision twice, not recomputing topology
twice.
To help diagnostics, I also add a message to show when GPU evaluation
is actually used to the modifier panel. Two frame counters are used
to suppress flicker in the UI panel.
Differential Revision: https://developer.blender.org/D17117
Pull Request #104441
Previously the UV unwrapping handling for subsurf modifiers used
`DerivedMesh`to implement the subdivision. Since we're trying to remove
`DerivedMesh` in general, and since this just made use of the `Mesh`
data anyway, it's relatively simple to remove it here. Combined with
D15939, this makes it possible to remove more `DerivedMesh` code.
Differential Revision: https://developer.blender.org/D16487
This commit replaces the `Mesh_Runtime` struct embedded in `Mesh`
with `blender::bke::MeshRuntime`. This has quite a few benefits:
- It's possible to use C++ types like `std::mutex`, `Array`,
`BitVector`, etc. more easily
- Meshes saved in files are slightly smaller
- Copying and writing meshes is a bit more obvious without
clearing of runtime data, etc.
The first is by far the most important. It will allows us to avoid a
bunch of manual memory management boilerplate that is error-prone and
annoying. It should also simplify future CoW improvements for runtime
data.
This patch doesn't change anything besides changing `mesh.runtime.data`
to `mesh.runtime->data`. The cleanups above will happen separately.
Differential Revision: https://developer.blender.org/D16180
