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.
This PR fixes a numbe of interconnected bugs:
* We weren't consistently uploading a dirty BitmapData to the render
backend before drawing to/from it.
* BitmapData.draw should *not* add a fill color - it should draw over
the current contents of the BitmapData
* After drawing to a non-transparent BitmapData, we need to manually
set the opacity back to 255 for each pixel (the drawing process
takes transparency into account, but the opacity information is
thrown away at the end).
These methods were incorrectly treating the argument as a local name,
instead of a qualified name. Additionally, 'getDefinition' now throws
an AVM error.
Previously, we would display an empty string for the method name.
We can now store a `&'static str` again in `NativeMethod`,
instead of needing a `Cow`
Now that we have a custom `Error` enum, this is very straightforwawrd.
I've converted `getDefinitionByName` return an AVM error, since this
is commonly used by games to test for a class.
Backends that need synchronous preload behavior now explicitly ask for it as follows:
* `tests` - repeatedly call `preload` in a loop with an exhausted execution limit to stress-test the chunked preload
* `exporter`, `scanner` - synchronous/unlimited preload to match prior behavior
These may change in the future.
Previously, we would only use mergeAlpha if alphaBitmapData
and alphaPoint. However, mergeAlpha can be used even when
those parameters are null.
Some of the AVM1 argument handling was also incorrect - I've fixed
it, and extended the existing test with the output-based test
added for AVM2.
Previously, we would always use a transparent background,
even if the BitmapData is not transparent. This would normally
be corrected on the next frame when we copied the pixels to the
CPU. However, if an SWF ran `BitmapData.draw` on every frame,
this would never be corrected.
When rendering offscreen, we want the resulting image to use
premultiplied alpha, since the image will be stored in a texture.
However, when capturing an image in the exporter or test framework,
we want to use straight alpha, so that the resulting image can
be saved as a PNG.
Previously, we incorrectly used straight alpha everywhere, resulting
in incorrect output when using BitmapData.draw with transparency.
Aaron Hill