Switch to Gregory basis patches which are tangent continuous across their
boundaries.
Originally we've used BSpline basis patches to be more compatible with the
old subdivision code, but a lot of things changed anyway.
No functional change, this adds LIB definition and args to cmake files.
Without this it's difficult to migrate away from 'BLENDER_SORTED_LIBS'
since there are many platforms/configurations that could break when
changing linking order.
Manually add and enable WITHOUT_SORTED_LIBS to try building
without sorted libs (currently fails since all variables are empty).
This check will eventually be removed.
See T46725.
This fixes following errors:
- The code didn't work correctly for edges reconstructed by
the OpenSubdiv's topology refiner (due to indexing
difference).
- Sharpness of non-manifold and boundary edges was not
working correctly.
Only affects internal API, bout could be exposed as an option for
the compatibility reasons with other software.
Is a part of some ongoing development of multires, but might or
might not be used.
C-API is way smaller than the rest of the code which uses it.
So better to conditionally compile stub implementation than
to keep adding ifdef everywhere.
Enabled infinite sharp patches for topology refiner and evaluator,
which allows to have sharp edge at first subdivision level.
Also tweaked crease export from Blender to OpenSubdiv to have more
artistic control over the whole 0..1 range.
The idea is simple: do not provide full topology to OpenSubdiv, leave
edges creation to OpenSubdiv itself. This solves issues with non-manifold
meshes which were known to fail, including the ones from T52059.
On a positive side we can simplify our side of converter, keeping code
shorter.
it is still possible that we'll need to ensure all loops has same
winding, but that is less things to worry about.
Applies to vertices and edges. Biggest annoyance here is that OpenSubdiv's
topology converter expects that there is no loose geometry, otherwise it
is getting confused.
For now solution is to create some sort of mapping from real Mesh vertex
and edge index to a non-loose-index. Now the annoying part is that this
is an extra step to calculate before we can compare topology, meaning FPS
will not be as great as if we knew for sure that topology didn't change.
Loose edges subdivision is different from what it used to be with old
subdivision code, but probably nice feature now is that endpoints of loose
edges are stay at the coarse vertex locations. This allows to have things
like plane with hair strands, without need to duplicate edge vertices at
endpoints.
All this required some re-work of topology refiner creation, which is now
only passing edges and vertices which are adjacent to face. This is how
topology refiner is supposed to be used, and this is how its validator
also works. Vertices which are adjacent to loose edges are marked as
infinite sharp. This seems to be good-enough approximation for now. In the
future we might tweaks things a bit and push such vertices in average
direction of loose edges, to match old subdivision code closer.
Only fixes compilation error, the functionality will be limited.
Currently we don't care that much, since all the work is done in
the branch anyway.
Later on when we'll know which fixes we need to apply on top of
latest OpenSubdiv library we will call a library upgrade.
