Commit Graph

45 Commits

Author SHA1 Message Date
ca45c2dc59 Fix T103756: wrong anonymous attribute tooltip 2023-01-09 14:52:06 +01:00
2ffd08e952 Geometry Nodes: deterministic anonymous attribute lifetimes
Previously, the lifetimes of anonymous attributes were determined by
reference counts which were non-deterministic when multiple threads
are used. Now the lifetimes of anonymous attributes are handled
more explicitly and deterministically. This is a prerequisite for any kind
of caching, because caching the output of nodes that do things
non-deterministically and have "invisible inputs" (reference counts)
doesn't really work.

For more details for how deterministic lifetimes are achieved, see D16858.

No functional changes are expected. Small performance changes are expected
as well (within few percent, anything larger regressions should be reported as
bugs).

Differential Revision: https://developer.blender.org/D16858
2023-01-05 14:05:30 +01:00
90ea1b7643 Nodes: Use persistent integer to identify to nodes
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
2022-12-01 15:08:12 -06:00
7549e0c5ae Geometry Nodes: use stringref instead of string in logger
This reduces logging overhead. The performance difference is only
significant when there are many fast nodes. In my test file with many
math nodes, the performance improved from 720ms to 630ms.
2022-09-17 12:08:57 +02:00
4130f1e674 Geometry Nodes: new evaluation system
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
2022-09-13 08:44:32 +02:00
25e307d725 Nodes: move NodeTreeRef functionality into node runtime data
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
2022-08-31 12:16:13 +02:00
1f94b56d77 Curves: support sculpting on deformed curves
Previously, curves sculpt tools only worked on original data. This was
very limiting, because one could effectively only sculpt the curves when
all procedural effects were turned off. This patch adds support for curves
sculpting while looking the result of procedural effects (like deformation
based on the surface mesh). This functionality is also known as "crazy space"
support in Blender.

For more details see D15407.

Differential Revision: https://developer.blender.org/D15407
2022-07-22 15:39:41 +02:00
6b84465352 Cleanup: remove dead code 2022-06-03 13:51:05 +02:00
44bac4c8cc Cleanup: use 'e' prefix for enum types
- CustomDataType -> eCustomDataType
- CustomDataMask -> eCustomDataMask
- AttributeDomain -> eAttrDomain
- NamedAttributeUsage -> eNamedAttrUsage
2022-06-01 15:38:48 +10:00
6a59cf0530 Nodes: add separately allocated runtime data for nodes and sockets
This is a follow up to rBbb0fc675822f313c5546a2498a162472c2571ecb.
Now the same kind of run-time data is added to nodes and sockets.

Differential Revision: https://developer.blender.org/D15060
2022-05-30 15:32:16 +02:00
42e275a7d4 Cleanup: use '_num' suffix, mostly for curves & spline code
Replace tot/amount & size with num, in keeping with T85728.
2022-05-11 13:38:00 +10:00
c71013082d Geometry Nodes: show used named attributes in nodes
This adds a new node editor overlay that helps users to see where
named attributes are used. This is important, because named
attributes can have name collisions between independent node
groups which can lead to hard to find issues.

Differential Revision: https://developer.blender.org/D14618
2022-04-14 16:31:09 +02:00
c434782e3a File headers: SPDX License migration
Use a shorter/simpler license convention, stops the header taking so
much space.

Follow the SPDX license specification: https://spdx.org/licenses

- C/C++/objc/objc++
- Python
- Shell Scripts
- CMake, GNUmakefile

While most of the source tree has been included

- `./extern/` was left out.
- `./intern/cycles` & `./intern/atomic` are also excluded because they
  use different header conventions.

doc/license/SPDX-license-identifiers.txt has been added to list SPDX all
used identifiers.

See P2788 for the script that automated these edits.

Reviewed By: brecht, mont29, sergey

Ref D14069
2022-02-11 09:14:36 +11:00
3060217d39 Cleanup: move public doc-strings into headers for 'nodes'
Ref T92709
2021-12-10 21:40:30 +11:00
a8e0fe6a54 Geometry Nodes: move type conversions to blenkernel
The type conversions do not depend on other files in the nodes
module. Furthermore we want to use the conversions in the
geometry module without creating a dependency to the
nodes module there.
2021-12-07 15:22:08 +01:00
97465046c6 Geometry Nodes: add utility to set remaining outputs
Differential Revision: https://developer.blender.org/D13384
2021-11-26 18:01:59 +01:00
31864a40ba Cleanup: use simple data member instead of callback
This really doesn't have to be a callback currently, since it is always
the same `CPPType` for a socket type.
2021-11-22 10:18:08 +01:00
d4c868da9f Geometry Nodes: refactor virtual array system
Goals of this refactor:
* Simplify creating virtual arrays.
* Simplify passing virtual arrays around.
* Simplify converting between typed and generic virtual arrays.
* Reduce memory allocations.

As a quick reminder, a virtual arrays is a data structure that behaves like an
array (i.e. it can be accessed using an index). However, it may not actually
be stored as array internally. The two most important implementations
of virtual arrays are those that correspond to an actual plain array and those
that have the same value for every index. However, many more
implementations exist for various reasons (interfacing with legacy attributes,
unified iterator over all points in multiple splines, ...).

With this refactor the core types (`VArray`, `GVArray`, `VMutableArray` and
`GVMutableArray`) can be used like "normal values". They typically live
on the stack. Before, they were usually inside a `std::unique_ptr`. This makes
passing them around much easier. Creation of new virtual arrays is also
much simpler now due to some constructors. Memory allocations are
reduced by making use of small object optimization inside the core types.

Previously, `VArray` was a class with virtual methods that had to be overridden
to change the behavior of a the virtual array. Now,`VArray` has a fixed size
and has no virtual methods. Instead it contains a `VArrayImpl` that is
similar to the old `VArray`. `VArrayImpl` should rarely ever be used directly,
unless a new virtual array implementation is added.

To support the small object optimization for many `VArrayImpl` classes,
a new `blender::Any` type is added. It is similar to `std::any` with two
additional features. It has an adjustable inline buffer size and alignment.
The inline buffer size of `std::any` can't be relied on and is usually too
small for our use case here. Furthermore, `blender::Any` can store
additional user-defined type information without increasing the
stack size.

Differential Revision: https://developer.blender.org/D12986
2021-11-16 10:16:30 +01:00
fc373af8f5 Nodes: store socket declaration reference in socket
Previously, to get the declaration of a socket, one had to go
through `node->declaration`. Now this indirection is not necessary
anymore. This makes it easier to add more per-socket information
into the declaration and accessing it in various places.

Currently, this system is used by socket descriptions and node warnings
for unsupported geometry component types.
2021-11-08 12:24:01 +01:00
cc6d5bc241 Fix: typo in info message 2021-10-27 15:31:00 +02:00
0bfae1b120 Geometry Nodes: geometry component type warning system
Previously, every node had to create warnings for unsupported input
geometry manually. Now this is automated. Nodes just have to specify
the geometry types they support in the node declaration.

Differential Revision: https://developer.blender.org/D12899
2021-10-26 20:00:10 +02:00
fd477e738d Geometry Nodes: remove reference to anonymous attributes in tooltips
This changes socket inspection for fields according to T91881.

Differential Revision: https://developer.blender.org/D13006
2021-10-26 15:32:01 +02:00
0081200812 Functions: remove multi-function network
The multi-function network system was able to compose multiple
multi-functions into a new one and to evaluate that efficiently.
This functionality was heavily used by the particle nodes prototype
a year ago. However, since then we only used multi-functions
without the need to compose them in geometry nodes.

The upcoming "fields" in geometry nodes will need a way to
compose multi-functions again. Unfortunately, the code removed
in this commit was not ideal for this different kind of function
composition. I've been working on an alternative that will be added
separately when it becomes needed.

I've had to update all the function nodes, because their interface
depended on the multi-function network data structure a bit.
The actual multi-function implementations are still the same though.
2021-08-20 13:14:39 +02:00
de91cdd930 Cleanup: separate base and geometry nodes specific socket cpp type
This simplifies changing how geometry nodes handles different socket types
without affecting other systems.
2021-08-02 10:34:50 +02:00
8e69409eed Fix T89775: geometry nodes logging crash during render
Under some circumstances (e.g. when rendering) the geometry
nodes logger is not used. This was missing a simple null check.
2021-07-12 14:29:28 +02:00
0153e99780 Geometry Nodes: refactor logging during geometry nodes evaluation
Many ui features for geometry nodes need access to information generated
during evaluation:
* Node warnings.
* Attribute search.
* Viewer node.
* Socket inspection (not in master yet).

The way we logged the required information before had some disadvantages:
* Viewer node used a completely separate system from node warnings and
  attribute search.
* Most of the context of logged information is lost when e.g. the same node
  group is used multiple times.
* A global lock was needed every time something is logged.

This new implementation solves these problems:
* All four mentioned ui features use the same underlying logging system.
* All context information for logged values is kept intact.
* Every thread has its own local logger. The logged informatiton is combined
  in the end.

Differential Revision: https://developer.blender.org/D11785
2021-07-07 11:20:19 +02:00
ed4222258e Geometry Nodes: Add Curve Subdivision Node
This node creates splines with more control points in between the
existing control points. The point is to give the splines more
definition for further tweaking like randomization with white noise,
instead of deforming a resampled poly spline with a noise texture.

For poly splines and NURBS, the node simply interpolates new values
between the existing control points. However, for Bezier splines,
the result follows the existing evaluated shape of the curve, changing
the handle positions and handle types to make that possible.

The number of "cuts" can be controlled by an integer input, or an
attribute can be used. Both spline and point domain attributes are
supported, so the number of cuts can vary using the value from the
point at the start of each segment.

Dynamic curve attributes are interpolated to the result with linear
interpolation.

Differential Revision: https://developer.blender.org/D11421
2021-06-17 11:39:23 -05:00
Jeroen Bakker
cb8a6814fd Blenlib: Explicit Colors.
Colors are often thought of as being 4 values that make up that can make any color.
But that is of course too limited. In C we didn’t spend time to annotate what we meant
when using colors.

Recently `BLI_color.hh` was made to facilitate color structures in CPP. CPP has possibilities to
enforce annotating structures during compilation and can adds conversions between them using
function overloading and explicit constructors.

The storage structs can hold 4 channels (r, g, b and a).

Usage:

Convert a theme byte color to a linearrgb premultiplied.
```
ColorTheme4b theme_color;
ColorSceneLinear4f<eAlpha::Premultiplied> linearrgb_color =
    BLI_color_convert_to_scene_linear(theme_color).premultiply_alpha();
```

The API is structured to make most use of inlining. Most notable are space
conversions done via `BLI_color_convert_to*` functions.

- Conversions between spaces (theme <=> scene linear) should always be done by
  invoking the `BLI_color_convert_to*` methods.
- Encoding colors (compressing to store colors inside a less precision storage)
  should be done by invoking the `encode` and `decode` methods.
- Changing alpha association should be done by invoking `premultiply_alpha` or
  `unpremultiply_alpha` methods.

# Encoding.

Color encoding is used to store colors with less precision as in using `uint8_t` in
stead of `float`. This encoding is supported for `eSpace::SceneLinear`.
To make this clear to the developer the `eSpace::SceneLinearByteEncoded`
space is added.

# Precision

Colors can be stored using `uint8_t` or `float` colors. The conversion
between the two precisions are available as methods. (`to_4b` and
`to_4f`).

# Alpha conversion

Alpha conversion is only supported in SceneLinear space.

Extending:
- This file can be extended with `ColorHex/Hsl/Hsv` for different representations
  of rgb based colors. `ColorHsl4f<eSpace::SceneLinear, eAlpha::Premultiplied>`
- Add non RGB spaces/storages ColorXyz.

Reviewed By: JacquesLucke, brecht

Differential Revision: https://developer.blender.org/D10978
2021-05-25 17:16:54 +02:00
00955cd31e Revert "Blenlib: Explicit Colors."
This reverts commit fd94e03344.
does not compile against latest master.
2021-05-25 17:03:54 +02:00
Jeroen Bakker
fd94e03344 Blenlib: Explicit Colors.
Colors are often thought of as being 4 values that make up that can make any color.
But that is of course too limited. In C we didn’t spend time to annotate what we meant
when using colors.

Recently `BLI_color.hh` was made to facilitate color structures in CPP. CPP has possibilities to
enforce annotating structures during compilation and can adds conversions between them using
function overloading and explicit constructors.

The storage structs can hold 4 channels (r, g, b and a).

Usage:

Convert a theme byte color to a linearrgb premultiplied.
```
ColorTheme4b theme_color;
ColorSceneLinear4f<eAlpha::Premultiplied> linearrgb_color =
    BLI_color_convert_to_scene_linear(theme_color).premultiply_alpha();
```

The API is structured to make most use of inlining. Most notable are space
conversions done via `BLI_color_convert_to*` functions.

- Conversions between spaces (theme <=> scene linear) should always be done by
  invoking the `BLI_color_convert_to*` methods.
- Encoding colors (compressing to store colors inside a less precision storage)
  should be done by invoking the `encode` and `decode` methods.
- Changing alpha association should be done by invoking `premultiply_alpha` or
  `unpremultiply_alpha` methods.

# Encoding.

Color encoding is used to store colors with less precision as in using `uint8_t` in
stead of `float`. This encoding is supported for `eSpace::SceneLinear`.
To make this clear to the developer the `eSpace::SceneLinearByteEncoded`
space is added.

# Precision

Colors can be stored using `uint8_t` or `float` colors. The conversion
between the two precisions are available as methods. (`to_4b` and
`to_4f`).

# Alpha conversion

Alpha conversion is only supported in SceneLinear space.

Extending:
- This file can be extended with `ColorHex/Hsl/Hsv` for different representations
  of rgb based colors. `ColorHsl4f<eSpace::SceneLinear, eAlpha::Premultiplied>`
- Add non RGB spaces/storages ColorXyz.

Reviewed By: JacquesLucke, brecht

Differential Revision: https://developer.blender.org/D10978
2021-05-25 17:01:26 +02:00
908bb03630 Geometry Nodes: improve geometry nodes evaluator internal api
This is a first step towards T87620.
It should not have any functional changes.

Goals of this refactor:
* Move the evaluator out of `MOD_nodes.cc`. That makes it easier to
  improve it in isolation.
* Extract core input/out parameter management out of `GeoNodeExecParams`.
  Managing this is the responsibility of the evaluator. This separation of
  concerns will be useful once we have lazy evaluation of certain inputs/outputs.

Differential Revision: https://developer.blender.org/D11085
2021-04-27 13:03:40 +02:00
b9a7b40924 Geometry Nodes: Get attribute domain and type without allocation
Because we use virtual classes (and for other reasons), we had to do a
small allocation when simply retrieving the data type and domain of an
existing attribute. This happened quite a lot actually-- to determine
these values for result attributes.

This patch adds a simple function to retrieve this meta data without
building the virtual array. This should lower the overhead of every
attribute node, though the difference probably won't be noticible
unless a tree has very many nodes.

Differential Revision: https://developer.blender.org/D11047
2021-04-22 08:05:02 -05:00
5cf6f570c6 Geometry Nodes: use virtual arrays in internal attribute api
A virtual array is a data structure that is similar to a normal array
in that its elements can be accessed by an index. However, a virtual
array does not have to be a contiguous array internally. Instead, its
elements can be layed out arbitrarily while element access happens
through a virtual function call. However, the virtual array data
structures are designed so that the virtual function call can be avoided
in cases where it could become a bottleneck.

Most commonly, a virtual array is backed by an actual array/span or
is a single value internally, that is the same for every index.
Besides those, there are many more specialized virtual arrays like the
ones that provides vertex positions based on the `MVert` struct or
vertex group weights.

Not all attributes used by geometry nodes are stored in simple contiguous
arrays. To provide uniform access to all kinds of attributes, the attribute
API has to provide virtual array functionality that hides the implementation
details of attributes.

Before this refactor, the attribute API provided its own virtual array
implementation as part of the `ReadAttribute` and `WriteAttribute` types.
That resulted in unnecessary code duplication with the virtual array system.
Even worse, it bound many algorithms used by geometry nodes to the specifics
of the attribute API, even though they could also use different data sources
(such as data from sockets, default values, later results of expressions, ...).

This refactor removes the `ReadAttribute` and `WriteAttribute` types and
replaces them with `GVArray` and `GVMutableArray` respectively. The `GV`
stands for "generic virtual". The "generic" means that the data type contained
in those virtual arrays is only known at run-time. There are the corresponding
statically typed types `VArray<T>` and `VMutableArray<T>` as well.

No regressions are expected from this refactor. It does come with one
improvement for users. The attribute API can convert the data type
on write now. This is especially useful when writing to builtin attributes
like `material_index` with e.g. the Attribute Math node (which usually
just writes to float attributes, while `material_index` is an integer attribute).

Differential Revision: https://developer.blender.org/D10994
2021-04-17 16:41:39 +02:00
d2869943d2 Nodes: refactor derived node tree
This is a complete rewrite of the derived node tree data structure.
It is a much thinner abstraction about `NodeTreeRef` than before.
This gives the user of the derived node tree more control and allows
for greater introspection capabilities (e.g. before muted nodes were
completely abstracted away; this was convenient, but came with
limitations).

Another nice benefit of the new structure is that it is much cheaper
to build, because it does not inline all nodes and sockets in nested
node groups.

Differential Revision: https://developer.blender.org/D10620
2021-03-06 16:51:06 +01:00
f53221bff7 UI: Allow translation for node error messages
This commit exposes the strings used in the node error messages for
localization. It also changes the message tooltip creation to
automatically add the period at the end, to be more consistent with
the (arguably bad) design of other tooltips in Blender.

Calling `TIP_` directly in the node implementation files allows us to
continue using `std::string` concatenation instead of passing variadic
arguments. It's also more explicit about which part of the message is
translated and which isn't. The files already include the translation
header anyway.
2021-03-03 12:58:33 -06:00
626a8e0f10 Fix T85979: Attribute missing warning with empty geometry
An error doesn't make sense in these situations because we don't expect
to find attributes on empty geometry, and an empty geometry set is a
valid situation.

Note that we can't use `component.is_empty` here, because often the
component is visually "empty" but still has a point cloud with no
points or a mesh with no vertices.
2021-02-25 08:20:02 -06:00
47fc1e11db Nodes: ensure ui storage implicitely
This makes it easier to use the api.
2021-02-19 11:27:40 +01:00
461d4fc1aa Geometry Nodes: Node error messages
This patch adds icons to the right side of nodes when they encounter a
a problem. When hovered, a tooltip displays describing the encountered
while evaluating the node.

Some examples are: attribute doesn't exist, mesh has no faces,
incorrect attribute type, etc. Exposing more messages to the system
will be an ongoing process. Multiple warnings per node are supported.

The system is implemented somewhat generically so that the basic
structure can also be used to store more information from evaluation
for the interface, like a list of available attributes.

Currently the messages are just button tooltips. They could be styled
differently in the future. Another limitation is that every instance of
a node group in a parent node tree will have the same error messages,
the "evaluation context" used to decide when to display the tooltips
must be extended to support node tree paths.

Differential Revision: https://developer.blender.org/D10290
2021-02-16 17:15:08 -06:00
eb2e260540 Cleanup: Used derived node in geometry exec params
Since the derived node tree is already build for the evaluation system,
it's simpler to pass a derived node to the params struct. This will also
allow context lookups in nested node groups for node error messages,
since the derived node has that information readily accessible.
2021-02-16 13:06:18 -06:00
39f60e6909 Geometry Nodes: move some attribute utilities to blenkernel
I need to access these utilities from modifier code as well.
Therefore, they should not live in the nodes module.
2021-02-16 11:55:12 +01:00
d7c2c889a6 Geometry Nodes: Allow attribute nodes to use different domains
Currently every attribute node assumes that the attribute exists on the
"points" domain, so it generally isn't possible to work with attributes
on other domains like edges, polygons, and corners.

This commit adds a heuristic to each attribute node to determine the
correct domain for the result attribute. In general, it works like this:
 - If the output attribute already exists, use that domain.
 - Otherwise, use the highest priority domain of the input attributes.
 - If none of the inputs are attributes, use the default domain (points).

For the implementation I abstracted the check a bit, but in each
node has a slightly different situation, so we end up with slightly
different `get_result_domain` functions in each node. I think this makes
sense, it keeps the code flexible and more easily understandable.

Note that we might eventually want to expose a domain drop-down to some
of the nodes. But that will be a separate discussion; this commit focuses
on making a more useful choice automatically.

Differential Revision: https://developer.blender.org/D10389
2021-02-12 12:46:17 -06:00
a8da70f70a Geometry Nodes: Add boolean attribute in utility function
This follows up rBc484b54453e607, adding the boolean custom property
data type in one more place that was missed.
2020-12-16 12:50:45 -06:00
49ec3cef69 Geometry Nodes: Input data type utility function
This commit adds a simple utility function for getting the data type of an
attribute or its "constant" socket counterparts. No functional changes.

Differential Revision: https://developer.blender.org/D9819
2020-12-14 11:43:54 -06:00
4a5f36638b Geometry Nodes: simplify supporting different input socket types for attributes
This is a non-functional change. The functionality introduced in this commit
is not used in master yet. It is used by nodes that are being developed in
other branches though.
2020-12-09 16:20:57 +01:00
6be56c13e9 Geometry Nodes: initial scattering and geometry nodes
This is the initial merge from the geometry-nodes branch.
Nodes:
* Attribute Math
* Boolean
* Edge Split
* Float Compare
* Object Info
* Point Distribute
* Point Instance
* Random Attribute
* Random Float
* Subdivision Surface
* Transform
* Triangulate

It includes the initial evaluation of geometry node groups in the Geometry Nodes modifier.

Notes on the Generic attribute access API

The API adds an indirection for attribute access. That has the following benefits:
* Most code does not have to care about how an attribute is stored internally.
  This is mainly necessary, because we have to deal with "legacy" attributes
  such as vertex weights and attributes that are embedded into other structs
  such as vertex positions.
* When reading from an attribute, we generally don't care what domain the
  attribute is stored on. So we want to abstract away the interpolation that
  that adapts attributes from one domain to another domain (this is not
  actually implemented yet).

Other possible improvements for later iterations include:
* Actually implement interpolation between domains.
* Don't use inheritance for the different attribute types. A single class for read
  access and one for write access might be enough, because we know all the ways
  in which attributes are stored internally. We don't want more different internal
  structures in the future. On the contrary, ideally we can consolidate the different
  storage formats in the future to reduce the need for this indirection.
* Remove the need for heap allocations when creating attribute accessors.

It includes commits from:
* Dalai Felinto
* Hans Goudey
* Jacques Lucke
* Léo Depoix
2020-12-02 15:38:47 +01:00