The issue was caused by the wrong attributes maps in certain
circumstances after union intersections.
Namely issue might have happen when more than one iteration of
union was happening and it was caused by the fact that new faces
might be allocated on the same address as freed face from the
old mesh.
Didn't find a nicer fix for this apart from correcting the whole
attributes map after each union step.
We could try removing attributes for the meshes which are getting
deleted, but in asymptotic it's gonna to give exactly the same
complexity as the current approach.
This was a nasty bug which was caused by specific of how face-edge
attributes are stored in Carve.
Face pointer is used in the map key which works just fine in all
cases except for the cases when some face is getting freed after
it was stored in the map.
This might give real issues when new face is allocating because
it's possible new face would have the same address as the freed
one.
Such cases used to happen when union of separate manifolds is
needed for the operands AND jemalloc is enabled.
Solved by dropping attributes for the freed faces from the map.
Maybe not the fastest ever approach, but not sure how to make
it faster actually. Should work just fine. It only happens for
complex setups with intersecting manifolds in the operands.
There were loads of issues in the code still which are mow likely fixed:
- Hole resolver hook had memory leak -- it didn't free face with holes
when triangulating it.
- Original edge mapping didn't work correct. old code related on the fact
that loop order is not changing when constructing the MeshSet class, but
in fact it does change.
Currently used edge map for this because it was easiest way to do it now,
but after the release we're to change it. Main reason is that face mapping
is not correct as well (and it was never correct actually). So we'll need
to construct Mesh structures by our own to be sure we're using correct
original index mapping.
- Carve might produce faces with ears, which is forbidden in Blender.
it wasn't an issue in old integration because triangulation will remove
the ears. So for now simply added ears removing back as a hook.
But actual reason of the ears is to be investigated really.
This hook will only work for NGons, quads are assumed not be able to
have ears. So this additional hook shouldn't slow down things much.
- Carve's hole resolver produces duplicated faces in some cases. Still not
sure what is the reason of this. Code here is not so much straightforward,
this is to be investigated later.
For now solved the issue as own hole resolver which checks for duplicated
faces after the hole resolving.
The additional checks here will only run if the mesh actually have hole
and wouldn't introduce slowdown for faces which doesn't have holes.
- Made it so if edge user triangulation gets a split (for example, in cases
when this edge intersects with the second operand) it wouldn't be dissolved.
This prevents cases of crappy topology after dissolving in several cases.
- Edge dissolver didn't check for whether edge is a non-manifold. We couldn't
really dissolve open manifold edges.
The bad thing about this is that mesh triangulation might produce non-manifold
edges and they wouldn't be dissolved. Not worst case in the world, but would
be nice to have it solved somehow.
- Exporting mesh form Carve to Blender might have produced duplicated edges
in cases when several non-manifold faces shared the edge. This is also fixed
now.
- Mesh triangulation might have produced duplicated faces, which is really bad.
Fixed by keeping a track on which faces we've created and skipping adding new
triangle if we already have one.
This all might introduce some slowdown, but we're too close to the release now,
so would rather have it slower but robust. After the release we might look into
ways to speed things up.
Goal of this commit is to support NGons for boolean modifier
(currently mesh is being tessellated before performing boolean
operation) and also solve the limitation of loosing edge custom
data layers after boolean operation is performed.
Main idea is to make it so boolean modifier uses Carve library
directly via it's C-API, avoiding BSP intermediate level which
was doubling amount of memory needed for the operation and which
also used quite reasonable amount of overhead time.
Perhaps memory usage and CPU usage are the same after all the
features are implemented but we've got support now:
- ORIGINDEX for all the geometry
- Interpolation of edge custom data (seams, crease)
- NGons support
Triangulation rule is changed now as well, so now non-flat
polygons are not being merged back after Carve work. This is
so because it's not so trivial to support for NGons and
having different behavior for quads and NGons is even more
creepy.
Reviewers: lukastoenne, campbellbarton
Differential Revision: https://developer.blender.org/D274
