This is part of T76372.
It adds the `blend_write`, `blend_read_data`, `blend_read_lib`
and `blend_read_expand` which correspond to the various
steps when reading and writing .blend files.
Having these callbacks allows us to decentralize the blenloader
code a lot more. This has the affect that code related to any
specific ID type is less scattered.
Reviewers: mont29
Differential Revision: https://developer.blender.org/D8670
High quality emitters need to maintain state themselves. For example,
this it needs to remember when it spawned the last particle.
This is especially important when the birth rate is changing over time.
Otherwise, there will be very visible artifacts.
It is quite likely that other components of the simulation need their own
state as well. Therefore, I refactored the `SimulationState` type a bit,
to make it more extensible. Instead of using hardcoded type numbers, a
string is used to identify the state type. Also, instead of having switch
statements in many places, there is a new `SimulationStateType` that
encapsulates information about how a specific state is created/freed/copied/...
I removed the integration with the point cache for now, because it was
not used anyway in it's current state.
Object sockets work now, but only the new Object Transforms and the
Particle Mesh Emitter node use it. The emitter does not actually
use the mesh surface yet. Instead, new particles are just emitted around
the origin of the object.
Internally, handles to object data blocks are passed around in the network,
instead of raw object pointers. Using handles has a couple of benefits:
* The caller of the function has control over which handles can be resolved
and therefore limit access to specific data. The set of data blocks that
is accessed by a node tree should be known statically. This is necessary
for a proper integration with the dependency graph.
* When the pointer to an object changes (e.g. after restarting Blender),
all handles are still valid.
* When an object is deleted, the handle is invalidated without causing crashes.
* The handle is just an integer that can be stored per particle and can be cached easily.
The mapping between handles and their corresponding data blocks is
stored in the Simulation data block.
Instead of depending on static initialization order of globals use
static variables within functions. Those are initialized on first use.
This is every so slighly less efficient, but avoids a full class of problems.
I removed bf_blenkernel from `nodes/CMakeLists.txt` again (added it yesterday),
because now this was causing me unresolved symbol errors... Without it, cmake
seems to link the libraries bf_simulation, bf_blenkernel and bf_nodes in the right
order. Not sure if that is just luck or if it is guaranteed.
It was possible to fix the issue by using cmakes `LINK_INTERFACE_MULTIPLICITY`,
but that is probably bad style.
This also introduces the `blender::nodes` namespace. Eventually,
we want to move most/all of the node implementation files into
this namespace.
The reason for this file-move is that the code fits much better
into the `nodes` directory than in the `blenkernel` directory.
`CD_LOCATION` was only used temporarily due to the lack
of a better alternative. This also removes the name from
`CD_LOCATION` again, because at most one layer of this
type should exist.
The force node can now be used to control the behavior of particles.
Forces can access particles attributes. Currently, there are three attributes:
`Position` (vector), `Velocity` (vector) and `ID` (integer).
Supported nodes are: Math, Vector Math, Separate Vector, Combine Vector and Value.
Next, I'll have to split `simulation.cc` into multiple files and move
some stuff out of blenkernel into another folder.
Every Particle Simulation node has a name (or a path when it is in a node group).
This name has to be used in the Simulation modifier on a point cloud to see
the particles.
Caching has been disabled for now, because it was holding back development
a bit. To reset the simulation, go back to frame 1.
Currently, there is no way to influence the simulation. There are just some
randomly moving points. Changing that is the next step.
This also renames `MutableArrayRef` to `MutableSpan`.
The name "Span" works better, because `std::span` will provide
similar functionality in C++20. Furthermore, a shorter, more
concise name for a common data structure is nice.
The current particle state is stored in a `CustomData` instance and
the cache is stored in `PointCache`.
The current state exists on the copy-on-write copies of the simulation,
while the cache only exists in the original data block.
This patch implements a temporary trivial particle simulation that does not
use the node system yet. It is used for testing and will be replaced soon.
`PointCache` still has some limitations that need to be overcome using
separate refactorings. For example, we need to be able to store the number
of particles in the point cache. Also we need to change which attributes
are stored for a particle system more dynamically than is currently possible afaik.
Reviewers: brecht
Differential Revision: https://developer.blender.org/D7836
For now the "Simulation" modifier only exists for point cloud objects, because
we need this for the particle system. Right now, the modifier is doing nothing.
There is a new `DEG_add_simulation_relation` function that is used
by the modifier to make sure that the simulation is evaluated before
the modifier is executed.
Reviewers: brecht, sergey
Differential Revision: https://developer.blender.org/D7549
This adds an embedded node tree to the simulation data block dna.
The UI in the `Simulation Editor` has been updated to show a list
of simulation data blocks, instead of individual node trees.
The new `SpaceNodeEditor.simulation` property wraps the existing
`SpaceNodeEditor.id` property. It allows scripts to get and set
the simulation data block that is being edited.
Reviewers: brecht, mont29
Differential Revision: https://developer.blender.org/D7301
This data block will be the container for simulation node trees.
It will be used for the new particle node system (T73324).
The new data block has the type `ID_SIM`.
It is not visible to users and other developers by default yet.
To enable it, activate the cmake option `WITH_NEW_SIMULATION_TYPE`.
New simulation data blocks can be created by running `bpy.data.simulations.new("name")`.
Reviewers: brecht
Differential Revision: https://developer.blender.org/D7225
