This evaluator is used in order to evaluate subdivision at render time, allowing for
faster renders of meshes with a subdivision surface modifier placed at the last
position in the modifier list.
When evaluating the subsurf modifier, we detect whether we can delegate evaluation
to the draw code. If so, the subdivision is first evaluated on the GPU using our own
custom evaluator (only the coarse data needs to be initially sent to the GPU), then,
buffers for the final `MeshBufferCache` are filled on the GPU using a set of
compute shaders. However, some buffers are still filled on the CPU side, if doing so
on the GPU is impractical (e.g. the line adjacency buffer used for x-ray, whose
logic is hardly GPU compatible).
This is done at the mesh buffer extraction level so that the result can be readily used
in the various OpenGL engines, without having to write custom geometry or tesselation
shaders.
We use our own subdivision evaluation shaders, instead of OpenSubDiv's vanilla one, in
order to control the data layout, and interpolation. For example, we store vertex colors
as compressed 16-bit integers, while OpenSubDiv's default evaluator only work for float
types.
In order to still access the modified geometry on the CPU side, for use in modifiers
or transform operators, a dedicated wrapper type is added `MESH_WRAPPER_TYPE_SUBD`.
Subdivision will be lazily evaluated via `BKE_object_get_evaluated_mesh` which will
create such a wrapper if possible. If the final subdivision surface is not needed on
the CPU side, `BKE_object_get_evaluated_mesh_no_subsurf` should be used.
Enabling or disabling GPU subdivision can be done through the user preferences (under
Viewport -> Subdivision).
See patch description for benchmarks.
Reviewed By: campbellbarton, jbakker, fclem, brecht, #eevee_viewport
Differential Revision: https://developer.blender.org/D12406
The spikes were caused by non-initialized tangent matrix used during
smoothing process. The reason tangent matrix was not initialized was
because wrong usage of API: n-gons should pass corner of 0 to the
matrix construction function.
Corrected usage of the API and added assert() to help catching such
kind of non-initialized issues easier.
Propagation when changing sculpt level was missing. In fact, the mask
was simply completely removed when changing sculpt level.
Subdivision worked for simple and linear subdivision, but Catmull-Clark
was giving empty results.
Fixes propagation part of T76386.
There is some hard-to-reproduce scenario when top level
would have masks allocated, but without masks on the sculpt
level.
Need to check proper array before accessing its elements.
The check for top-level masks is done by the caller.
When using multires_reshape_context_create_from_ccg to create the
context mmd is null, so the subdivision smooth mode can't be checked
there.
Reviewed By: sergey
Differential Revision: https://developer.blender.org/D7579
This introduces two alternative subdivision modes that generates
displacement on the grids that look as Simple subdivisions but while
using the Catmull-Clark subdivision type in the modifier. This way,
Simple and Catmull-Clark subdivision can be combined when creating new
levels if needed, for example, to sculpt hard surface objects.
Subdivide simple smooths the sculpted data when creating a new
subdivision level. Subdivide linear also preserves the sharpness
in the sculpted data.
Reviewed By: sergey
Differential Revision: https://developer.blender.org/D7415
Allows to know what level sculpting has been done after the value has
been changed in the MultiresModifierData.
No functional changes, just preparing code to have everything needed
for propagation undo.
Differential Revision: https://developer.blender.org/D7307
Is done by considering all base edges infinitely sharp.
In the future can become a different operator option to allow to mix
Catmull-Clark and simple subdivisions. For now just sticking to what
old good Blender versions were doing.
Fixes T74869: Simple subdivision type is not working as it should
The idea is following: only store information about edges which are
1. Communicated to the OpenSubdiv topology.
This rules out all loose edges, as they are not needed for the
propagation process.
2. Correspond to edge from the base mesh.
This avoids storing edges which are generated between inner face.
Those are not to have any sharpness to allow smooth propagation.
There is still possible to have memory peak in some obscure case when
mesh contains a lot of loose edges. It can be optimized further by
utilizing knowledge of the non-loose tags.
The title says it all actually. The test case is to get default cube,
set some edges to non-zero crease, add multires modifier and hit the
"Subdivide" button few times.
The memory footprint might be optimized by not storing information
about inner generated edges.
This change fixes artifacts produced by these operations.
On a technical aspect this is done by porting all of the operations
to the new subdivision surface implementation which ensures that
tangent space used to evaluate modifier and those operations is
exactly the same (before modifier will use new code and the operations
will still use an old one).
The next step is to get sculpting on a non-top level to work, and
that actually requires fixes in the undo system.
