Consistently use edge draw flag instead of original index to determine if an
edge should be drawn or not.
In GPU subdivision the edge original index was used for both edge optimal
display and selection mapping to coarse edges, but they are not the same.
Now match the CPU subdivision logic and use a separate edge draw flag VBO.
For cage display, match Blender 3.3 behavior more in showing/hiding of edges
in wireframe mode. That is edges without a mapping to an original edge are
always hidden when there is no distinct cage, and drawn otherwise. This is
not ideal for e.g. the bevel modifier where it will always show some edges on
corners despite all edges being hidden by the user. But we currently have
no good information to decide if these should be hidden or not, so err on
the side of showing too much as it did before.
Fie #103706: bevel modifier edges not drawn correctly
Fix#103700: optimal display can't be turned of with GPU subdivision
Fix wrong edge display with GPU subdivision preceded by other modifiers
Pull Request #105384
Addendum to previous fix, which was for point selection, this fixes the
face selection mode. The issue is caused by wrong flags used for paint
mode (the edit mode flag was always used). Also add back flag which was
accidentally removed in 16f5d51109.
The normals flags were not setup properly which made normals for all
elements (vertices, faces) to be drawn when using the normals overlay.
Also remove usage of uints for the flag in the APIs.
Faces, edges, and vertices are still shown when GPU subdivision is
actived. This is because the related edit mode flags were ignored by the
subdivision code.
The flags are now passed to the various compute shaders mostly as part of
the extra coarse data, also used for e.g. selection. For loose edges, a
temporary buffer is created when extracting them. Loose vertices are
already taken into account as it reuses the routines for coarse mesh
extraction, although `MeshRenderData.use_hide` was not initialized,
which is fixed now.
The lines paint mask IBO extraction was not implemented for GPU subdivision.
For it to work, we also now need to preserve the subdivision loop to
subdivision edge map, which until now was overwritten to store coarse edges
(the map to coarse edges is still preserved).
Also the paint flag stored in the 4th dimension of the loop normal buffer
was not properly set for flat shaded faces, leading to other kind of
artefacts and render issues.
Reuse the same vertex normals calculation as for the GPU code, by
weighing each vertex normals by the angle of the edges incident to the
vertex on the face.
Additionally, remove limit normals, as the CPU code does not use them
either, and would also cause different shading issues when limit surface
is used.
Fixes T95242: shade smooth artifacts with edge crease and limit surface
Fixes T94919: subdivision, different shading between CPU and GPU
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
