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
Currently you can retrieve a mutable array from a const CustomData.
That makes code unsafe since the compiler can't check for correctness
itself. Fix that by introducing a separate function to retrieve mutable
arrays from CustomData. The new functions have the `_for_write`
suffix that make the code's intention clearer.
Because it makes retrieving write access an explicit step, this change
also makes proper copy-on-write possible for attributes.
Notes:
- The previous "duplicate referenced layer" functions are redundant
with retrieving layers with write access
- The custom data functions that give a specific index only have
`for_write` to simplify the API
Differential Revision: https://developer.blender.org/D14140
**Changes**
As described in T93602, this patch removes all use of the `MVert`
struct, replacing it with a generic named attribute with the name
`"position"`, consistent with other geometry types.
Variable names have been changed from `verts` to `positions`, to align
with the attribute name and the more generic design (positions are not
vertices, they are just an attribute stored on the point domain).
This change is made possible by previous commits that moved all other
data out of `MVert` to runtime data or other generic attributes. What
remains is mostly a simple type change. Though, the type still shows up
859 times, so the patch is quite large.
One compromise is that now `CD_MASK_BAREMESH` now contains
`CD_PROP_FLOAT3`. With the general move towards generic attributes
over custom data types, we are removing use of these type masks anyway.
**Benefits**
The most obvious benefit is reduced memory usage and the benefits
that brings in memory-bound situations. `float3` is only 3 bytes, in
comparison to `MVert` which was 4. When there are millions of vertices
this starts to matter more.
The other benefits come from using a more generic type. Instead of
writing algorithms specifically for `MVert`, code can just use arrays
of vectors. This will allow eliminating many temporary arrays or
wrappers used to extract positions.
Many possible improvements aren't implemented in this patch, though
I did switch simplify or remove the process of creating temporary
position arrays in a few places.
The design clarity that "positions are just another attribute" brings
allows removing explicit copying of vertices in some procedural
operations-- they are just processed like most other attributes.
**Performance**
This touches so many areas that it's hard to benchmark exhaustively,
but I observed some areas as examples.
* The mesh line node with 4 million count was 1.5x (8ms to 12ms) faster.
* The Spring splash screen went from ~4.3 to ~4.5 fps.
* The subdivision surface modifier/node was slightly faster
RNA access through Python may be slightly slower, since now we need
a name lookup instead of just a custom data type lookup for each index.
**Future Improvements**
* Remove uses of "vert_coords" functions:
* `BKE_mesh_vert_coords_alloc`
* `BKE_mesh_vert_coords_get`
* `BKE_mesh_vert_coords_apply{_with_mat4}`
* Remove more hidden copying of positions
* General simplification now possible in many areas
* Convert more code to C++ to use `float3` instead of `float[3]`
* Currently `reinterpret_cast` is used for those C-API functions
Differential Revision: https://developer.blender.org/D15982
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
Use `verts` instead of `vertices` and `polys` instead of `polygons`
in the API added in 05952aa94d. This aligns better with
existing naming where the shorter names are much more common.
For copy-on-write, we want to share attribute arrays between meshes
where possible. Mutable pointers like `Mesh.mvert` make that difficult
by making ownership vague. They also make code more complex by adding
redundancy.
The simplest solution is just removing them and retrieving layers from
`CustomData` as needed. Similar changes have already been applied to
curves and point clouds (e9f82d3dc7, 410a6efb74). Removing use of
the pointers generally makes code more obvious and more reusable.
Mesh data is now accessed with a C++ API (`Mesh::edges()` or
`Mesh::edges_for_write()`), and a C API (`BKE_mesh_edges(mesh)`).
The CoW changes this commit makes possible are described in T95845
and T95842, and started in D14139 and D14140. The change also simplifies
the ongoing mesh struct-of-array refactors from T95965.
**RNA/Python Access Performance**
Theoretically, accessing mesh elements with the RNA API may become
slower, since the layer needs to be found on every random access.
However, overhead is already high enough that this doesn't make a
noticible differenc, and performance is actually improved in some
cases. Random access can be up to 10% faster, but other situations
might be a bit slower. Generally using `foreach_get/set` are the best
way to improve performance. See the differential revision for more
discussion about Python performance.
Cycles has been updated to use raw pointers and the internal Blender
mesh types, mostly because there is no sense in having this overhead
when it's already compiled with Blender. In my tests this roughly
halves the Cycles mesh creation time (0.19s to 0.10s for a 1 million
face grid).
Differential Revision: https://developer.blender.org/D15488
* Flip the logic to first detect if we are dealing with an unmodified mesh
in editmode. And then if not, detect if we need a mapping or not.
* runtime.is_original is only valid for the bmesh wrapper. Rename it to clarify
that and only check it when the mesh is a bmesh wrapper.
* Remove MR_EXTRACT_MAPPED and instead check only for the existence of the
origindex arrays. Previously it would sometimes access those arrays without
MR_EXTRACT_MAPPED set, which according to a comment means they are invalid.
Differential Revision: https://developer.blender.org/D15676
A mesh wrapper might be being accessed for read-only from one thread
while another thread converts the wrapper type to something else.
The proposes solution is to defer assignment of the mesh wrapper
type until the wrapper is fully converted. The good thing about this
approach is that it does not introduce extra synchronization (and,
potentially, evaluation pipeline stalls). The downside is that it
might not work with all possible wrapper types in the future. If a
wrapper type which does not clear data separation is ever added in
the future we will re-consider the threading safety then.
Unfortunately, some changes outside of the mesh wrapper file are
to be made to allow "incremental" construction of the mesh prior
changing its wrapper type.
Unfortunately, there is no simplified file which demonstrates the
issue. It was investigated using Heist production file checked at
the revision 1228: `pro/lib/char/einar/einar.shading.blend`. The
repro case is simple: tab into edit mode, possibly few times.
The gist is that there several surface deform and shrinkwrap
modifiers which uses the same target. While one of them is building
BVH tree (which changes wrapper type) the other one accesses it for
read-only via `BKE_mesh_wrapper_vert_coords_copy_with_mat4()`.
Differential Revision: https://developer.blender.org/D15424
It was looking up the last modifier in the stack, ignoring visibility, instead
of mesh->runtime.subsurf_runtime_data set by the modifier evaluation and used by
the drawing code.
Instancing with geometry nodes uses just the evaluated Mesh, and ignores the
Object that it came from. That meant that it would try to look up the subsurf
modifier on the instancer object which does not have the subsurf modifier.
Instead of storing a session UUID and looking up the modifier data, store a
point to the subsurf modifier runtime data. Unlike the modifier data, this
runtime data is preserved across depsgraph CoW. It must be for the subdiv
descriptor contained in it to stay valid along with the draw cache.
As a bonus, this moves various Mesh_Runtime variables into the subsurf runtime
data, reducing memory usage for meshes not using subdivision surfaces.
Also fixes T98693, issues with subdivision level >= 8 due to integer overflow.
Differential Revision: https://developer.blender.org/D15184
The crash is caused as the subdivision wrapper does not have loop
normals, which are generally computed at the end of the modifier stack
evaluation via `mesh_calc_modifier_final_normals`. (Note that they are
initially computed, but deleted by the subdivision wrapper creation.)
This records in the mesh runtime whether loop normals should have been
computed and computes them alongside the subdivision wrapper.
Differential Revision: https://developer.blender.org/D14489
