When using the bitmap.wgsl shader for normal rendering, we need
to saturate immediately after applying the color transformation
to reproduce Flash Player's behavior. This makes the (possibly
transformed) alpha value get multiplied by a in-range color,
instead of a potentially out-of-range color.
However, Stage3D just applies a no-op color transformation,
and should only saturate at the very end
(not after the intermediate division by the original alpha value).
To support both of these requirements, I've added in a new
`early_saturate` ifdef that controls when we apply 'saturate'.
We then compile the shader twice (once with early_saturate=true
and once with early_saturate=false), and use the two versions
in the right pipelines.
We could use a simpler shader for Stage3D - however, it can't just
be a plain copy, as we need to apply the viewport transformation.
For now, I'm re-using the shader code to keep things simple. If
this becomes a performance issue in stage3d, we could revisit this.
Based on the work in #6717, plus additional adaptions mentioned in
https://github.com/gfx-rs/wgpu/blob/master/CHANGELOG.md#wgpu-013-2022-06-30,
and more not-mentioned but required changes.
Also bump `wasm-bindgen` to `0.2.81` (along with its helper crates), as
required by the new `wgpu` version.
Note that I don't fully understand some of the required changes, notably:
* `wgpu::PresentMode::Mailbox` no longer works on my machine (Windows 11) -
The `wgpu` documentation says that `wgpu::PresentMode::Fifo` is the
only guaranteed to be supported, so I switched over to it instead.
* `self.staging_belt.recall()` doesn't return a `Future` anymore -
I assume it became synchronous so I simply removed the `executor`
from there.
Always use a non-sRGB texture as the render target so that color
and alpha blending are in sRGB space, matching Flash behavior.
If the surface format requires sRGB, render to an intermediate
linear buffer and copy to the surface as a final render step.
naga is currently lenient about some things which are invalid by
the WGSL spec. The Tint WGSL compiler disagreed, so these shaders
failed to compile in Chrome.
TÖRÖK Attila