This allows us to avoid many calls to `as_span()` methods. I will
remove those in the next commit. Furthermore, constructors
of Vector and Array can convert from one type to another now.
I tested these changes on Linux with gcc and on Windows.
This can be used to find separate islands in meshes efficiently (as is
done in cycles already). Furthermore, this helps to implement some
algorithms on node trees more efficiently.
Each duplicated (a.k.a. instanced) object has a Persistent ID, which
identifies a dupli within the context of its duplicator. This ID
consists of several numbers when there are nested duplis (for example a
mesh instancing empties on its vertices, where each empty instances a
collection). When exporting to Alembic/USD, these are used to uniquely
name the duplicated objects in the export.
This commit reverses the order of the persistent ID numbers, so that the
first number identifies the first level of recursion. This produces
trees like this:
ABC
`--Triangle
|--Triangle
|--Empty-1
| `--Pole-1-0
| |--Pole
| `--Block-1-1
| `--Block
|--Empty
| `--Pole-0
| |--Pole
| `--Block-1
| `--Block
|--Empty-2
| `--Pole-2-0
| |--Pole
| `--Block-2-1
| `--Block
`--Empty-0
`--Pole-0-0
|--Pole
`--Block-0-1
`--Block
It is now clearer that `Pole-2-0` and `Block-2-1` are instanced by
`Empty-2`. Before this commit, they would have been named `Pole-0-2` and
`Block-1-2`.
Exporting a scene to USD or Alembic would fail when there are multiple
duplicates of parent & child objects, duplicated by the same object. For
example, this happens when such a hierarchy of objects is contained in a
collection, and that collection is instanced multiple times by mesh
vertices. The problem here is that the 'parent' pointer of each
duplicated object points to the real parent; Blender would not figure
out properly which duplicated parent should be used.
This is now resolved by keeping track of the persistent ID of each
duplicated instance, which makes it possible to reconstruct the
parent-child relations of duplicated objects. This does use up some
memory for each dupli, so it could be heavy to export a Spring scene
(with all the pebbles and leaves), but it's only a small addition on top
of the USD/Alembic writer objects that have to be created anyway. At
least with this patch, they're created correctly.
Code-wise, the following changes are made:
- The export graph (that maps export parent to its export children) used
to have as its key (Object, Duplicator). This is insufficient to
correctly distinguish between multiple duplis of the same object by
the same duplicator, so this is now extended to (Object, Duplicator,
Persistent ID). To make this possible, new classes `ObjectIdentifier`
and `PersistentID` are introduced.
- Finding the parent of a duplicated object is done via its persistent
ID. In Python notation, the code first tries to find the parent
instance where `child_persistent_id[1:] == parent_persistent_id[1:]`.
If that fails, the dupli with persistent ID `child_persistent_id[1:]`
is used as parent.
Reviewed By: sergey
Differential Revision: https://developer.blender.org/D8233
Even if we do not use exception in many places in Blender, our core C++ library
should become exception safe. Otherwise, we don't even have the option
to work with exceptions if we decide to do so.
The issue is duplicated code. There are two functions that zero-fill
the frame number. They worked the same for positive frames numbers, but
behaved differently for negative ones.
On frame `-100`, `BLI_path_frame` outputs `-0100` and
`fluid_cache_get_framenr_formatted_$ID$` outputted `-100`.
I changed the behavior of the latter, because we depend on the behavior
of the former for much longer already.
Reviewers: sebbas
Differential Revision: https://developer.blender.org/D8107
The Alembic exporter has been restructured by leverages the
`AbstractHierarchyIterator` introduced by the USD exporter. The produced
Alembic files have not changed much (details below), as the Alembic
writing code has simply been moved from the old exporter to the new. How
the export hierarchy is handled changed a lot, though, and also the way
in which transforms are computed. As a result, T71395 is fixed.
Differences between the old and new exporter, in terms of the produced
Alembic file:
- Duplicated objects now have a unique numerical suffix.
- Matrices are computed differently, namely by simply computing the
evaluated transform of the object relative to the evaluated transform
of its export-parent. This fixes {T71395}, but otherwise should
produce the same result as before (but with simpler code).
Compared to the old Alembic exporter, Subdivision modifiers are now
disabled in a cleaner, more efficient way (they are disabled when
exporting with the "Apply Subdivisions" option is unchecked). Previously
the exporter would move to a new frame, disable the modifier, evaluate
the object, and enable the modifier again. This is now done before
exporting starts, and modifiers are only restored when exporting ends.
Some issues with the old Alembic exporter that have NOT been fixed in
this patch:
- Exporting NURBS patches and curves (see T49114 for example).
- Exporting flattened hierarchy in combination with dupli-objects. This
seems to be broken in the old Alembic exporter as well, but nobody
reported this yet.
Differential Revision: https://developer.blender.org/D7664
Reviewed By: Sergey
A multi-function network is a graph data structure, where nodes are
multi-functions (or dummies) and links represent data flow.
New multi-functions can be derived from such a network. For that
one just has to specify two sets of sockets in the network that
represent the inputs and outputs of the new function.
It is possible to do optimizations like constant folding on this
data structure, but that is not implemented in this patch yet.
In a next step, user generated node trees are converted into a
MFNetwork, so that they can be evaluated efficiently for many particles.
This patch also includes some tests that cover the majority of the code.
However, this seems to be the kind of code that is best tested by some
.blend files. Building graph structures in code is possible, but is
not easy to understand afterwards.
Reviewers: brecht
Differential Revision: https://developer.blender.org/D8049
This commit only moves code into the `blender::io::alembic` namespace,
it does not move `static` functions into an anonymous namespace.
No functional changes.
This moves most of the exporter-related code
from `source/blender/io/alembic/intern`
to `source/blender/io/alembic/exporter`
This is to prepare the Alembic code for the switchover to using
`blender::io::AbstractHierarchyIterator`. When that happens, a few more
files will be added, and having things in a separate 'exporter'
directory makes things less cluttered.
Note that exporting consists of multiple steps (determine export
hierarchy, create Alembic archive, and then write data into it), which
is why the directory is called "exporter", but many of the files are
called "writer".
No functional changes.
This isn't really in C++ standard, some corner cases work in some
compilers (like when all fields are specified), but in general they
do not work.
For some reason MSVC builder started to complain about it now,
weird but better not rely on compiler specifics.
Are reported by MSVC 2019 after C++17 switch.
One might suggest lets just silence the warning, I will say why to have
specific signed/unsigned types in API just to then (usafely) ignore the
sign conversion.
This is in order to prepare for compatibility with the Alembic exporter.
That exporter is capable of writing object transforms and object data at
different (sub)frames.
The rename from `created_writers` to `used_writers` is necessary, as not
all created writers will be actually used in each iteration.
The Universal Scene Description (USD) exporter does not make use of
this.
Reviewed By: mont29
Differential Revision: https://developer.blender.org/D7670
The goal of the `AbstractHierarchyIterator` class (and supporting
classes) was to use it in different exporters. It shouldn't be part of
the USD module + namespace any more, now that it will also be used in
the upcoming Alembic exporter rewrite.
The source files are moved into `io/common`, which is compiled & linked
into a new library `bf_io_common`. The unittests are still inside the
`tests/gtests/usd` directory. They should be moved to a separate test
module too, but that will be delayed until after T73268 has been
resolved.
Reviewed By: mont29
Differential Revision: https://developer.blender.org/D7669
The matrix interpolation function `interp_m3_m3m3()` decomposes the
matrices into rotation and scale matrices, converts the rotation
matrices to quaternions, SLERPs the quaternions, and converts the result
back to a matrix. Since quaternions cannot represent axis flips, this
results in interpolation problems like described in T77154.
Our interpolation function is based on "Matrix Animation and Polar
Decomposition", by Ken Shoemake & Tom Duff. The paper states that it
produces invalid results when there is an axis flip in the rotation
matrix (or negative determinant, or negative scale, those all indicate
the same thing). Their solution is to multiply the rotation matrix with
`-I`, where `I` is the identity matrix. This is the same as element-wise
multiplication with `-1.0f`. My proposed solution is to not only do that
with the rotation matrix `R`, but also with the scale matrix `S`. This
ensures that the decomposition of `A = R * S` remains valid, while also
making it possible to conver the rotation component to a quaternion.
There is still an issue when interpolating between matrices with
different determinant. As the determinant represents the change in
volume when that matrix is applied to an object, interpolating between a
negative and a positive matrix will have to go through a zero
determinant. In this case the volume collapses to zero. I don't see this
as a big issue, though, as without this patch Blender would also produce
invalid results anyway.
Reviewed By: brecht, sergey
Differential Revision: https://developer.blender.org/D8048
The interpolation of 4x4 and 3x3 matrices will fail when the rotation
component has a singularity, i.e. when there is one axis mirrored. Two
mirrored axes are just a rotation of 180 degrees around the third, and
three mirrored axes are such a rotation + a single axis mirror. To
prepare for a fix, I first wanted to cover the basic functionality with
a few unit tests.
These tests check that `interpolate(A, B, alpha)` always returns `A` for
`alpha=0`, always return `B` for `alpha=1`, and something in between for
`alpha=0.5`.
This adds the `MultiFunction` type and some smallish utility types that it uses.
A `MultiFunction` encapsulates a function that is optimized for throughput by
always processing many elements at once.
This is an important part of the new particle system, because it allows us to
execute user generated node trees for many particles efficiently.
Reviewers: brecht
Differential Revision: https://developer.blender.org/D8030
Smells like GCC bug [1], which is backed up by the fact that locally
GCC-10 and CLang-10 works fine.
Since the change is trivial (and, arguably, correct since there is
no real difference between tests code and actual code) seems fine to
fix.
Fix suggested by Jacques Lucke, thanks!
[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=56480
