* wpgu: Initial implementation of PixelBender shader execution
The implementation is split across four crates:
* `ruffle_render` now holds the main PixelBender bytecode parsing
implementation (previously, this was in `ruffle_core`).
* `ruffle_core` holds some helper functions for converting between
AVM2 `Value`s and the PixelBender vector types.
* `naga-pixelbender` (newly created) constructs a Naga `Module`
from parsed PixelBender bytecode
* `ruffle_render_wgpu` sets up the render pipeline for the shader
constructed by `naga-pixelbender`, and actually executes the shader.
The Actionscript-side shader parameters are passed in through uniforms.
This allows us to cache the compiled `naga::Module` and associated
wgpu types inside `ShaderData`, when it's first created. Each invocation
of a `ShaderJob` only needs to create a bind group and render pass.
Limitations:
* Only a few of the PixelBender opcodes are implemented - however, this is
enough to get Stemlands cannon rotation working, as well as a cool
"donut" shader that I found and included as a test.
* PixelBender matrix types are not supported.
* Only BitmapData is supported as an input/output type - Flash Player
also supports using Vector and ByteArray
* ShaderJob execution is always synchronous.
* Adjust comments
* Address review comments
We create a separate child domain, which is accessible
from the Stage and the root movieclip.
This prevents ActionScript from loading classes into the
special playerglobals domain (Domain.parentDomain is modified
to return null instead of the playerglobals domain when applicable),
so the native method lookup logic will never run for user code.
This lets us print the full error message and stack stacke
in contexts where an Activation is not available, including
the `Debug` impl.
The 'name' and 'error' fields are accessed using hardcodd slot
ids. This is pretty hacky, but will work until we have better
handling of slot properties.
Lord-McSweeney