[Impeller] In advanced blends, unpremultiply and apply src_input_alpha only if there is no foreground color #50260
Conversation
| v_src_texture_coords // texture coordinates | ||
| )); | ||
| src *= blend_info.src_input_alpha; | ||
| )) * blend_info.src_input_alpha; |
There was a problem hiding this comment.
When applying blend_info.src_input_alpha to an unpremultiplied color, only the a component should be adjusted, otherwise the color components will become darker as it becomes more transparent.
| @@ -41,13 +41,12 @@ void main() { | |||
| v_dst_texture_coords // texture coordinates | |||
| )); | |||
| dst *= blend_info.dst_input_alpha; | |||
| f16vec4 src = IPHalfUnpremultiply( | |||
| f16vec4 src = | |||
| blend_info.color_factor > 0.0hf | |||
| ? blend_info.color | |||
There was a problem hiding this comment.
This change makes sense... this color never gets premultiplied on the CPU side before we get here. Could you add a comment saying this color is expected to be unpremultiplied in the shader struct where it's defined?
There was a problem hiding this comment.
That comment already exists:
https://github.com/flutter/engine/blob/main/impeller/entity/shaders/blending/advanced_blend.frag#L18
jason-simmons
force-pushed
the
bug_142620
branch
from
0303177
to
6dd4fc2
Compare
…a only if there is no foreground color See flutter/flutter#142620
jason-simmons
force-pushed
the
bug_142620
branch
from
6dd4fc2
to
1c44c07
Compare
|
Golden file changes have been found for this pull request. Click here to view and triage (e.g. because this is an intentional change). If you are still iterating on this change and are not ready to resolve the images on the Flutter Gold dashboard, consider marking this PR as a draft pull request above. You will still be able to view image results on the dashboard, commenting will be silenced, and the check will not try to resolve itself until marked ready for review. |
jason-simmons
added
the
autosubmit
…input_alpha only if there is no foreground color (flutter/engine#50260)
…142848) flutter/engine@fee0214...23763db 2024-02-03 chinmaygarde@google.com [Impeller] Fix blown stack due to always out of date window dimensions on high-dpi devices. (flutter/engine#50307) 2024-02-02 jason-simmons@users.noreply.github.com [Impeller] In advanced blends, unpremultiply and apply src_input_alpha only if there is no foreground color (flutter/engine#50260) 2024-02-02 30870216+gaaclarke@users.noreply.github.com [Impeller] new blur: clamp downsample scalar to 1/16 (flutter/engine#50262) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-engine-flutter-autoroll Please CC matanl@google.com,rmistry@google.com,zra@google.com on the revert to ensure that a human is aware of the problem. To file a bug in Flutter: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md
See flutter/flutter#142620