We aim to make the C# API reflection-free, mainly for concerns about
performance, and to be able to target NativeAOT in refletion-free mode,
which reduces the binary size.
One of the main usages of reflection still left was the dynamic
invokation of callable delegates, and for some time I wasn't sure
I would find an alternative solution that I'd be happy with.
The new solution uses trampoline functions to invoke the delegates:
```
static void Trampoline(object delegateObj, NativeVariantPtrArgs args, out godot_variant ret)
{
if (args.Count != 1)
throw new ArgumentException($"Callable expected 1 arguments but received {args.Count}.");
string res = ((Func<int, string>)delegateObj)(
VariantConversionCallbacks.GetToManagedCallback<int>()(args[0])
);
ret = VariantConversionCallbacks.GetToVariantCallback<string>()(res);
}
Callable.CreateWithUnsafeTrampoline((int num) => "Foo" + num, &Trampoline);
```
Of course, this is too much boilerplate for user code. To improve this,
the `Callable.From` methods were added. These are overloads that take
`Action` and `Func` delegates, which covers the most common use cases:
lambdas and method groups:
```
// Lambda
Callable.From((int num) => "Foo" + num);
// Method group
string AppendNum(int num) => "Foo" + num;
Callable.From(AppendNum);
```
Unfortunately, due to limitations in the C# language, implicit
conversions from delegates to `Callable` are not supported.
`Callable.From` does not support custom delegates. These should be
uncommon, but the Godot C# API actually uses them for event signals.
As such, the bindings generator was updated to generate trampoline
functions for event signals. It was also optimized to use `Action`
instead of a custom delegate for parameterless signals, which removes
the need for the trampoline functions for those signals.
The change to reflection-free invokation removes one of the last needs
for `ConvertVariantToManagedObjectOfType`. The only remaining usage is
from calling script constructors with parameters from the engine
(`CreateManagedForGodotObjectScriptInstance`). Once that one is made
reflection-free, `ConvertVariantToManagedObjectOfType` can be removed.
Changed the signal declaration signal to:
```
// The following generates a MySignal event
[Signal] public delegate void MySignalEventHandler(int param);
```
Previously, for each scripts class instance that was created from code
rather than by the engine, we were constructing, configuring and
assigning a new CSharpScript.
This has changed now and we make sure there's only one CSharpScript
associated to each type.
The editor no longer needs to create temporary instances to get the
default values. The initializer values of the exported properties are
still evaluated at runtime. For example, in the following example,
`GetInitialValue()` will be called when first looks for default values:
```
[Export] int MyValue = GetInitialValue();
```
Exporting fields with a non-supported type now results in a compiler
error rather than a runtime error when the script is used.
This base implementation is still very barebones but it defines the path
for how exporting will work (at least when embedding the .NET runtime).
Many manual steps are still needed, which should be automatized in the
future. For example, in addition to the API assemblies, now you also
need to copy the GodotPlugins assembly to each game project.
Finalizers are longer guaranteed to be called on exit now that
we switched to .NET Core. This results in native instances leaking.
The only solution I can think of so far is to keep a list of all
instances alive to dispose when the AssemblyLoadContext.Unloading
event is raised.
We're targeting .NET 5 for now to make development easier while
.NET 6 is not yet released.
TEMPORARY REGRESSIONS
---------------------
Assembly unloading is not implemented yet. As such, many Godot
resources are leaked at exit. This will be re-implemented later
together with assembly hot-reloading.
The main focus here was to remove the majority of code that relied on
Mono's embedding APIs, specially the reflection APIs. The embedding
APIs we still use are the bare minimum we need for things to work.
A lot of code was moved to C#. We no longer deal with any managed
objects (`MonoObject*`, and such) in native code, and all marshaling
is done in C#.
The reason for restructuring the code and move away from embedding APIs
is that once we move to .NET Core, we will be limited by the much more
minimal .NET hosting.
PERFORMANCE REGRESSIONS
-----------------------
Some parts of the code were written with little to no concern about
performance. This includes code that calls into script methods and
accesses script fields, properties and events.
The reason for this is that all of that will be moved to source
generators, so any work prior to that would be a waste of time.
DISABLED FEATURES
-----------------
Some code was removed as it no longer makes sense (or won't make sense
in the future).
Other parts were commented out with `#if 0`s and TODO warnings because
it doesn't make much sense to work on them yet as those parts will
change heavily when we switch to .NET Core but also when we start
introducing source generators.
As such, the following features were disabled temporarily:
- Assembly-reloading (will be done with ALCs in .NET Core).
- Properties/fields exports and script method listing (will be
handled by source generators in the future).
- Exception logging in the editor and stack info for errors.
- Exporting games.
- Building of C# projects. We no longer copy the Godot API assemblies
to the project directory, so MSBuild won't be able to find them. The
idea is to turn them into NuGet packages in the future, which could
also be obtained from local NuGet sources during development.
We will be progressively moving most code to C#.
The plan is to only use Mono's embedding APIs to set things at launch.
This will make it much easier to later support CoreCLR too which
doesn't have rich embedding APIs.
Additionally the code in C# is more maintainable and makes it easier
to implement new features, e.g.: runtime codegen which we could use to
avoid using reflection for marshaling everytime a field, property or
method is accessed.
SOME NOTES ON INTEROP
We make the same assumptions as GDNative about the size of the Godot
structures we use. We take it a bit further by also assuming the layout
of fields in some cases, which is riskier but let's us squeeze out some
performance by avoiding unnecessary managed to native calls.
Code that deals with native structs is less safe than before as there's
no RAII and copy constructors in C#. It's like using the GDNative C API
directly. One has to take special care to free values they own.
Perhaps we could use roslyn analyzers to check this, but I don't know
any that uses attributes to determine what's owned or borrowed.
As to why we maily use pointers for native structs instead of ref/out:
- AFAIK (and confirmed with a benchmark) ref/out are pinned
during P/Invoke calls and that has a cost.
- Native struct fields can't be ref/out in the first place.
- A `using` local can't be passed as ref/out, only `in`. Calling a
method or property on an `in` value makes a silent copy, so we want
to avoid `in`.
REGARDING THE BUILD SYSTEM
There's no longer a `mono_glue=yes/no` SCons options. We no longer
need to build with `mono_glue=no`, generate the glue and then build
again with `mono_glue=yes`. We build only once and generate the glue
(which is in C# now).
However, SCons no longer builds the C# projects for us. Instead one
must run `build_assemblies.py`, e.g.:
```sh
%godot_src_root%/modules/mono/build_scripts/build_assemblies.py \
--godot-output-dir=%godot_src_root%/bin \
--godot-target=release_debug`
```
We could turn this into a custom build target, but I don't know how
to do that with SCons (it's possible with Meson).
OTHER NOTES
Most of the moved code doesn't follow the C# naming convention and
still has the word Mono in the names despite no longer dealing with
Mono's embedding APIs. This is just temporary while transitioning,
to make it easier to understand what was moved where.
Implement built-in classes Vector4, Vector4i and Projection.
* Two versions of Vector4 (float and integer).
* A Projection class, which is a 4x4 matrix specialized in projection types.
These types have been requested for a long time, but given they were very corner case they were not added before.
Because in Godot 4, reimplementing parts of the rendering engine is now possible, access to these types (heavily used by the rendering code) becomes a necessity.
**Q**: Why Projection and not Matrix4?
**A**: Godot does not use Matrix2, Matrix3, Matrix4x3, etc. naming convention because, within the engine, these types always have a *purpose*. As such, Godot names them: Transform2D, Transform3D or Basis. In this case, this 4x4 matrix is _always_ used as a _Projection_, hence the naming.
- Add support for explicit values in properties using `PROPERTY_HINT_FLAGS`
that works the same way it does for enums.
- Fix enums and flags in VisualScriptEditor (it wasn't considering the
explicit value).
- Use `PROPERTY_HINT_FLAGS` for C# enums with the FlagsAttribute instead
of `PROPERTY_HINT_ENUM`.
This commit completely removes the RPC_MODE_MASTER ("master" keyword),
and renames the RPC_MODE_PUPPET to RPC_MODE_AUTHORITY ("auth" keyword).
This commit also renames the "Node.[get|set]_network_master" methods to
"Node.[get|set]_network_authority".
This commit also renames the RPC_MODE_REMOTE constant to RPC_MODE_ANY.
RPC_MODE_MASTER in Godot 3.x meant that a given RPC would be callable by
any puppet peer on the master, while RPC_MODE_PUPPET meant that it would
be callable by the master on any puppet.
Beside proving to be very confusing to the user (referring to where it
could be called instead of who can call it) the RPC_MODE_MASTER is quite
useless. It is almost the same as RPC_MODE_REMOTE (anyone can call) with
the exception that the network master cannot. While this could be useful
to check in some case, in such a function you would anyway need to check
in code who is the caller via get_rpc_sender_id(), so adding the check
there for those rare cases does not warrants a dedicated mode.
- Move the "sync" property for RPCs to RPCConfig.
- Unify GDScript annotations into a single one:
- `@rpc(master)` # default
- `@rpc(puppet)`
- `@rpc(any)` # former `@remote`
- Implement three additional `@rpc` options:
- The second parameter is the "sync" option (which also calls the
function locally when RPCing). One of "sync", "nosync".
- The third parameter is the transfer mode (reliable, unreliable,
ordered).
- The third parameter is the channel (unused for now).
This source generator adds a newly introduced attribute,
`ScriptPath` to all classes that:
- Are top-level classes (not inner/nested).
- Have the `partial` modifier.
- Inherit `Godot.Object`.
- The class name matches the file name.
A build error is thrown if the generator finds a class that meets these
conditions but is not declared `partial`, unless the class is annotated
with the `DisableGodotGenerators` attribute.
We also generate an `AssemblyHasScripts` assembly attribute which Godot
uses to get all the script classes in the assembly, eliminating the need
for Godot to search them. We can also avoid searching in assemblies that
don't have this attribute. This will be good for performance in the
future once we support multiple assemblies with Godot script classes.
This is an example of what the generated code looks like:
```
using Godot;
namespace Foo {
[ScriptPathAttribute("res://Player.cs")]
// Multiple partial declarations are allowed
[ScriptPathAttribute("res://Foo/Player.cs")]
partial class Player {}
}
[assembly:AssemblyHasScripts(new System.Type[] { typeof(Foo.Player) })]
```
The new attributes replace script metadata which we were generating by
determining the namespace of script classes with a very simple parser.
This fixes several issues with the old approach related to parser
errors and conditional compilation.
It also makes the task part of the MSBuild project build, rather than
a separate step executed by the Godot editor.
Happy new year to the wonderful Godot community!
2020 has been a tough year for most of us personally, but a good year for
Godot development nonetheless with a huge amount of work done towards Godot
4.0 and great improvements backported to the long-lived 3.2 branch.
We've had close to 400 contributors to engine code this year, authoring near
7,000 commit! (And that's only for the `master` branch and for the engine code,
there's a lot more when counting docs, demos and other first-party repos.)
Here's to a great year 2021 for all Godot users 🎆
Which means that reduz' beloved style which we all became used to
will now be changed automatically to remove the first empty line.
This makes us lean closer to 1TBS (the one true brace style) instead
of hybridating it with some Allman-inspired spacing.
There's still the case of braces around single-statement blocks that
needs to be addressed (but clang-format can't help with that, but
clang-tidy may if we agree about it).
Part of #33027.
Don't store GC handles for C# script instances and instance bindings as 'Ref<MonoGCHandle>'; store the raw data instead. Initially this was not possible as we needed to store a Variant, but this had not been the case for a looong time yet the stored type was never updated.
Implementation for new Variant types Callable, Signal, StringName.
Added support for PackedInt64Array and PackedFloat64Array.
Add generation of signal members as events, as well as support for
user created signals as events.
NOTE: As of now, raising such events will not emit the signal. As such,
one must use `EmitSignal` instead of raising the event directly.
Removed old ThreadLocal fallback class. It's safe to use thread_local now since
it's supported on all minimum versions of compilers we support.
Happy new year to the wonderful Godot community!
We're starting a new decade with a well-established, non-profit, free
and open source game engine, and tons of further improvements in the
pipeline from hundreds of contributors.
Godot will keep getting better, and we're looking forward to all the
games that the community will keep developing and releasing with it.
- Added correct config file for android dllmaps.
- Fix __Internal DllImports with a dlopen fallback.
- Add missing P/Invoke functions and internal calls expected by the monodroid BCL and our custom version of the 'Android.Runtime.AndroidEnvironment' class (this last one can be found in the godot-mono-builds repo).
- Make sure to set 'btls' instead of 'legacy' as the default TLS provider on Android.
