The simulation state used by simulation nodes is owned by the modifier. Since a
geometry nodes setup can contain an arbitrary number of simulations, the modifier
has a mapping from `SimulationZoneID` to `SimulationZoneState`. This patch changes
what is used as `SimulationZoneID`.
Previously, the `SimulationZoneID` contained a list of `bNode::identifier` that described
the path from the root node tree to the simulation output node. This works ok in many
cases, but also has a significant problem: The `SimulationZoneID` changes when moving
the simulation zone into or out of a node group. This implies that any of these operations
loses the mapping from zone to simulation state, invalidating the cache or even baked data.
The goal of this patch is to introduce a single-integer ID that identifies a (nested) simulation
zone and is stable even when grouping and un-grouping. The ID should be stable even if the
node group containing the (nested) simulation zone is in a separate linked .blend file and
that linked file is changed.
In the future, the same kind of ID can be used to store e.g. checkpoint/baked/frozen data
in the modifier.
To achieve the described goal, node trees can now store an arbitrary number of nested node
references (an array of `bNestedNodeRef`). Each nested node reference has an ID that is
unique within the current node tree. The node tree does not store the entire path to the
nested node. Instead it only know which group node the nested node is in, and what the
nested node ID of the node is within that group. Grouping and un-grouping operations
have to update the nested node references to keep the IDs stable. Importantly though,
these operations only have to care about the two node groups that are affected. IDs in
higher level node groups remain unchanged by design.
A consequence of this design is that every `bNodeTree` now has a `bNestedNodeRef`
for every (nested) simulation zone. Two instances of the same simulation zone (because
a node group is reused) are referenced by two separate `bNestedNodeRef`. This is
important to keep in mind, because it also means that this solution doesn't scale well if
we wanted to use it to keep stable references to *all* nested nodes. I can't think of a
solution that fulfills the described requirements but scales better with more nodes. For
that reason, this solution should only be used when we want to store data for each
referenced nested node at the top level (like we do for simulations).
This is not a replacement for `ViewerPath` which can store a path to data in a node tree
without changing the node tree. Also `ViewerPath` can contain information like the loop
iteration that should be viewed (#109164). `bNestedNodeRef` can't differentiate between
different iterations of a loop. This also means that simulations can't be used inside of a
loop (loops inside of a simulation work fine though).
When baking, the new stable ID is now written to disk, which means that baked data is
not invalidated by grouping/un-grouping operations. Backward compatibility for baked
data is provided, but only works as long as the simulation zone has not been moved to
a different node group yet. Forward compatibility for the baked data is not provided
(so older versions can't load the data baked with a newer version of Blender).
Pull Request: https://projects.blender.org/blender/blender/pulls/109444
The `logically_linked_sockets` runtime data of sockets is only initialized
for inputs. This patch also initializes it for output sockets through
the inversion the inputs logically_linked_sockets structure.
Pull Request: https://projects.blender.org/blender/blender/pulls/109249
A lot of files were missing copyright field in the header and
the Blender Foundation contributed to them in a sense of bug
fixing and general maintenance.
This change makes it explicit that those files are at least
partially copyrighted by the Blender Foundation.
Note that this does not make it so the Blender Foundation is
the only holder of the copyright in those files, and developers
who do not have a signed contract with the foundation still
hold the copyright as well.
Another aspect of this change is using SPDX format for the
header. We already used it for the license specification,
and now we state it for the copyright as well, following the
FAQ:
https://reuse.software/faq/
See: https://projects.blender.org/blender/blender/issues/103343
Changes:
1. Added `BKE_node.hh` file. New file includes old one.
2. Functions moved to new file. Redundant `(void)`, `struct` are removed.
3. All cpp includes replaced from `.h` on `.hh`.
4. Everything in `BKE_node.hh` is on `blender::bke` namespace.
5. All implementation functions moved in namespace.
6. Function names (`BKE_node_*`) changed to `blender::bke::node_*`.
7. `eNodeSizePreset` now is a class, with renamed items.
Pull Request: https://projects.blender.org/blender/blender/pulls/107790
This adds support for building simulations with geometry nodes. A new
`Simulation Input` and `Simulation Output` node allow maintaining a
simulation state across multiple frames. Together these two nodes form
a `simulation zone` which contains all the nodes that update the simulation
state from one frame to the next.
A new simulation zone can be added via the menu
(`Simulation > Simulation Zone`) or with the node add search.
The simulation state contains a geometry by default. However, it is possible
to add multiple geometry sockets as well as other socket types. Currently,
field inputs are evaluated and stored for the preceding geometry socket in
the order that the sockets are shown. Simulation state items can be added
by linking one of the empty sockets to something else. In the sidebar, there
is a new panel that allows adding, removing and reordering these sockets.
The simulation nodes behave as follows:
* On the first frame, the inputs of the `Simulation Input` node are evaluated
to initialize the simulation state. In later frames these sockets are not
evaluated anymore. The `Delta Time` at the first frame is zero, but the
simulation zone is still evaluated.
* On every next frame, the `Simulation Input` node outputs the simulation
state of the previous frame. Nodes in the simulation zone can edit that
data in arbitrary ways, also taking into account the `Delta Time`. The new
simulation state has to be passed to the `Simulation Output` node where it
is cached and forwarded.
* On a frame that is already cached or baked, the nodes in the simulation
zone are not evaluated, because the `Simulation Output` node can return
the previously cached data directly.
It is not allowed to connect sockets from inside the simulation zone to the
outside without going through the `Simulation Output` node. This is a necessary
restriction to make caching and sub-frame interpolation work. Links can go into
the simulation zone without problems though.
Anonymous attributes are not propagated by the simulation nodes unless they
are explicitly stored in the simulation state. This is unfortunate, but
currently there is no practical and reliable alternative. The core problem
is detecting which anonymous attributes will be required for the simulation
and afterwards. While we can detect this for the current evaluation, we can't
look into the future in time to see what data will be necessary. We intend to
make it easier to explicitly pass data through a simulation in the future,
even if the simulation is in a nested node group.
There is a new `Simulation Nodes` panel in the physics tab in the properties
editor. It allows baking all simulation zones on the selected objects. The
baking options are intentially kept at a minimum for this MVP. More features
for simulation baking as well as baking in general can be expected to be added
separately.
All baked data is stored on disk in a folder next to the .blend file. #106937
describes how baking is implemented in more detail. Volumes can not be baked
yet and materials are lost during baking for now. Packing the baked data into
the .blend file is not yet supported.
The timeline indicates which frames are currently cached, baked or cached but
invalidated by user-changes.
Simulation input and output nodes are internally linked together by their
`bNode.identifier` which stays the same even if the node name changes. They
are generally added and removed together. However, there are still cases where
"dangling" simulation nodes can be created currently. Those generally don't
cause harm, but would be nice to avoid this in more cases in the future.
Co-authored-by: Hans Goudey <h.goudey@me.com>
Co-authored-by: Lukas Tönne <lukas@blender.org>
Pull Request: https://projects.blender.org/blender/blender/pulls/104924
Since internal links are only runtime data, we have the flexibility to
allocating every link individually. Instead we can store links directly
in the node runtime vector. This allows avoiding many small allocations
when copying and changing node trees.
In the future we could use a smaller type like a pair of sockets
instead of `bNodeLink` to save memory.
Differential Revision: https://developer.blender.org/D16960
Previously, the code tried to keep node groups working even if some of
their input/output sockets had undefined type. This caused some
complexity with no benefit because not all places outside of this file
would handle the case correctly. Now node groups with undefined
interface sockets are disabled and have to be fixed manually before
they work again.
Undefined interface sockets are mostly caused by invalid Python
API usage and incomplete forward compatibility (e.g. when newer
versions introduce new socket types that the older version does
not know).
Add `bNode::index()` to allow accessing node indices directly without
manually de-referencing the runtime struct. Also adds some asserts to
make sure the access is valid and to check the nodes runtime vector.
Eagerly maintain the node's index in the tree so it can be accessed
without relying on the topology cache.
Differential Revision: https://developer.blender.org/D16683
This patch adds an integer identifier to nodes that doesn't change when
the node name changes. This identifier can be used by different systems
to reference a node. This may be important to store caches and simulation
states per node, because otherwise those would always be invalidated
when a node name changes.
Additionally, this kind of identifier could make some things more efficient,
because with it an integer is enough to identify a node and one does not
have to store the node name.
I observed a 10% improvement in evaluation time in a file with an extreme
number of simple math nodes, due to reduced logging overhead-- from
0.226s to 0.205s.
Differential Revision: https://developer.blender.org/D15775
This allows for optimizations because one does not have to iterate
over all nodes anymore to find all nodes within a frame.
Differential Revision: https://developer.blender.org/D16106
This was essentially a use-after-free issue. When a geometry nodes
group changes it has to be preprocessed again before it can be evaluated.
This part was working, the issue was that parent node groups have to be
preprocessed as well, which was missing. The lazy-function graph cached
on the parent node group was still referencing data that was freed when
the child group changed.
Now the depsgraph makes sure that all relevant geometry node groups are
preprocessed again after a change.
This issue was found by Simon Thommes.
This refactors the geometry nodes evaluation system. No changes for the
user are expected. At a high level the goals are:
* Support using geometry nodes outside of the geometry nodes modifier.
* Support using the evaluator infrastructure for other purposes like field evaluation.
* Support more nodes, especially when many of them are disabled behind switch nodes.
* Support doing preprocessing on node groups.
For more details see T98492.
There are fairly detailed comments in the code, but here is a high level overview
for how it works now:
* There is a new "lazy-function" system. It is similar in spirit to the multi-function
system but with different goals. Instead of optimizing throughput for highly
parallelizable work, this system is designed to compute only the data that is actually
necessary. What data is necessary can be determined dynamically during evaluation.
Many lazy-functions can be composed in a graph to form a new lazy-function, which can
again be used in a graph etc.
* Each geometry node group is converted into a lazy-function graph prior to evaluation.
To evaluate geometry nodes, one then just has to evaluate that graph. Node groups are
no longer inlined into their parents.
Next steps for the evaluation system is to reduce the use of threads in some situations
to avoid overhead. Many small node groups don't benefit from multi-threading at all.
This is much easier to do now because not everything has to be inlined in one huge
node tree anymore.
Differential Revision: https://developer.blender.org/D15914
The purpose of `NodeTreeRef` was to speed up various queries on a read-only
`bNodeTree`. Not that we have runtime data in nodes and sockets, we can also
store the result of some queries there. This has some benefits:
* No need for a read-only separate node tree data structure which increased
complexity.
* Makes it easier to reuse cached queries in more parts of Blender that can
benefit from it.
A downside is that we loose some type safety that we got by having different
types for input and output sockets, as well as internal and non-internal links.
This patch also refactors `DerivedNodeTree` so that it does not use
`NodeTreeRef` anymore, but uses `bNodeTree` directly instead.
To provide a convenient API (that is also close to what `NodeTreeRef` has), a
new approach is implemented: `bNodeTree`, `bNode`, `bNodeSocket` and `bNodeLink`
now have C++ methods declared in `DNA_node_types.h` which are implemented in
`BKE_node_runtime.hh`. To make this work, `makesdna` now skips c++ sections when
parsing dna header files.
No user visible changes are expected.
Differential Revision: https://developer.blender.org/D15491
