Direct buffer copies are required to perform certain operations more efficiently, as the only current alternative is to download the buffer to the CPU and upload it again. As the first use case, the new function is used when enabling motion vectors on multimeshes.
The first time a shader is compiled Godot performs the following:
```cpp
for (uint32_t i = 0; i < SHADER_STAGE_MAX; i++) {
if
(spirv_data.push_constant_stages_mask.has_flag((ShaderStage)(1 << i))) {
binary_data.push_constant_vk_stages_mask |=
shader_stage_masks[i];
}
}
```
However binary_data.push_constant_vk_stages_mask is never initialized to
0 and thus contains garbage data or'ed with the good data.
This value is used by push constants (and many other things) thus it can
be a big deal.
Fortunately because the relevant flags are always guaranteed to be set
(but not guaranteed to be unset), the damage is restricted to:
1. Performance (unnecessary flushing & over-excessive barriers)
2. Overwriting push descriptors already set (this would be serious,
doesn't seem to be an issue)
3. Driver implementations going crazy when they see bits set they don't
expect (unknown if this is an issue)
This uninitialized value is later saved into the binary cache.
Valgrind is able to detect this bug on the first run, but not on the
subsequent ones because they data comes from a file.
cache_file_version has been bumped to force rebuild of all cached
shaders. Because the ones generated so far are compromised.
This allows us to specify a subset of variants to compile at load time and conditionally other variants later.
This works seamlessly with shader caching.
Needed to ensure that users only pay the cost for variants they use
As many open source projects have started doing it, we're removing the
current year from the copyright notice, so that we don't need to bump
it every year.
It seems like only the first year of publication is technically
relevant for copyright notices, and even that seems to be something
that many companies stopped listing altogether (in a version controlled
codebase, the commits are a much better source of date of publication
than a hardcoded copyright statement).
We also now list Godot Engine contributors first as we're collectively
the current maintainers of the project, and we clarify that the
"exclusive" copyright of the co-founders covers the timespan before
opensourcing (their further contributions are included as part of Godot
Engine contributors).
Also fixed "cf." Frenchism - it's meant as "refer to / see".
Implements basic ASTC support:
* Only 4x4 and 8x8 block sizes.
* Other block sizes are too complex to handle for Godot image compression handling. May be implemented sometime in the future.
The need for ASTC is mostly for the following use cases:
* Implement a high quality compression option for textures on mobile and M1 Apple hardware.
* For this, the 4x4 is sufficient, since it uses the same size as BPTC.
ASTC supports a lot of block sizes, but the benefit of supporting most of them is slim, while the implementation complexity in Godot is very high.
Supporting only 4x4 (and 8x8) solves the real problem, which is lack of a BPTC alternative on hardware where it's missing.
Note: This does not yet support encoding on import, an ASTC encoder will need to be added.
