These are poorly documented, but from looking at OpenFL
and AGALMiniAssembler, they allow performing loads of the
form `vc[va0.x + offset]` - that is, computing a dynamic register
number, instead of using the register number present in the opcode.
This is a very large diff, but most of it comes from test files and
output.
This PR ads partial support for the following Stage3D shader features:
* Normal (square), rectangle, and cube textures
* Varying and temporary registers
* Lots of opcodes
The combination of these allows us to get a raytracing program
fully working in Ruffle. I've included it as image test.
Currently, this test is very slow (about 90 seconds on my machine),
as the code I'm using (https://github.com/saharan/OGSL) includes
its own shader language and compiler. THe raytracing demo
first compiles its own shader language to AGAL, and then starts
rendering the scene.
Limitations:
* Many opcodes are still unimplemented
* Most non-default texture options (e.g. mipmaps) are not implemented
This is the first part of the Stage3D implementation, and can
be reviewed independently.
Stage3D shaders use the Adobe Graphics Assembly Language (AGAL),
which is a binary shader format. It supports vertex attributes,
varying registers, program constants (uniforms), and texture sampling.
This PR only implements a few parts of AGAL:
* The 'mov' and 'm44' opcodes
* Vertex attributes, varying registers, program constants, and 'output'
registers (position or color, depending on shader type)
This is sufficient to get a non-trivial Stage3D program
running (the rotating cube demo from the Adobe docs).
The output of `naga-agal` is a `naga::Module`. This can be passed
directly to wgpu, or compiled into a shader language using
a Naga backend (glsl, wgsl, SPIR-V, etc). The test suite
output WGSL files, and uses the 'insta' crate to compare against
saved files on disk.
Currently, the only real way to write AGAL bytecode is using
the Adobe-provided 'AGALMiniAssembler' flash class.
This class assembles the textual reprentation of AGAL into
the binary format.
To make writing tests easier, I've added a 'agal_compiler' test, which
can easily be modified to add more Agal textual assembly.
Aaron Hill