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Handle complex RSE rendering in the uber SDF pipeline#186434

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walley892:rse-full
May 29, 2026
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Handle complex RSE rendering in the uber SDF pipeline#186434
auto-submit[bot] merged 19 commits into
flutter:masterfrom
walley892:rse-full

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@walley892 walley892 commented May 13, 2026

Updates the uber SDF shader pipeline to support complex RSEs with asymmetric corner radii.

This works by breaking the RSE into four quadrants, and evaluating them separately.

Separates the rendering paths for symmetric and asymmetric RSEs so symmetric RSEs don't need as much branching.

Also tucks the parameter unpacking into uber_sdf_contents.cc, because the canvas code was getting bloated.

Adds unit tests and a golden.

Will need to update malioc

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@flutter-dashboard flutter-dashboard Bot added the CICD Run CI/CD label May 13, 2026
@github-actions github-actions Bot added engine flutter/engine related. See also e: labels. e: impeller Impeller rendering backend issues and features requests labels May 13, 2026
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/gemini review

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Code Review

This pull request enables SDF rendering for asymmetric rounded superellipses by transitioning from single-quadrant to per-quadrant parameter processing. Key changes include updating UberSDFParameters to store quadrant data in Vector4 types and rewriting the uber_sdf.frag shader to evaluate all four quadrants. Feedback highlights a critical bug where an uninitialized variable grad_norm is used in the shader, as well as opportunities to optimize performance by using split points for branching and removing the unused distanceToSegment function.

Comment thread engine/src/flutter/impeller/entity/shaders/uber_sdf.frag Outdated
Comment thread engine/src/flutter/impeller/entity/shaders/uber_sdf.frag Outdated
Comment thread engine/src/flutter/impeller/entity/shaders/uber_sdf.frag Outdated
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@walley892 walley892 requested a review from gaaclarke May 13, 2026 20:37
@walley892 walley892 added the CICD Run CI/CD label May 13, 2026
@walley892 walley892 requested a review from dkwingsmt May 13, 2026 20:42
@walley892 walley892 marked this pull request as ready for review May 13, 2026 20:43
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Code Review

This pull request enables the rendering of asymmetric rounded superellipses via Signed Distance Fields (SDFs). The implementation refactors the UberSDF pipeline to store and process per-quadrant geometric parameters using Vector4 structures in both the C++ host code and the fragment shader. Feedback suggests unifying the component ordering of corner radii across different shape types to maintain consistency with the shader's quadrant indexing logic.

Comment thread engine/src/flutter/impeller/entity/contents/uber_sdf_parameters.cc Outdated
Comment thread engine/src/flutter/impeller/entity/contents/uber_sdf_parameters_unittests.cc Outdated
@walley892 walley892 changed the title Rse full Handle complex RSE rendering in the uber SDF pipeline May 13, 2026
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Hey @walley892, the golden for impeller_Play_AiksTest_CanRenderAsymmetricRoundSuperellipses_MetalSDF doesn't look right https://flutter-gold.skia.org/search?issue=186434&crs=github&patchsets=6&corpus=flutter

07619c7a3bdd6ae11109ea18e903ac5f

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Confirmed with steamboat willie that the goldens look good locally on his M1 and my M4. Investigating

Screenshot 2026-05-14 at 10 12 11 AM

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It's not going to make this PR much bigger. Mostly the logic will just be moved from one file to another. Let's just get it over with now.

From the glsl perspective, yeah. the c++ is where the code bloat is mostly happening - split things out

@walley892 walley892 requested a review from gaaclarke May 26, 2026 20:37
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LGTM, there is just some minor formatting that needs to be fixed. I like us to make this lazy loaded, that can be a followup though. Nice work @walley892

Comment thread engine/src/flutter/impeller/entity/contents/complex_rse_contents.cc Outdated
Comment thread engine/src/flutter/impeller/entity/contents/complex_rse_contents.h
Comment thread engine/src/flutter/impeller/entity/contents/content_context.cc
Comment thread engine/src/flutter/impeller/entity/shaders/complex_rse.frag Outdated
Comment thread engine/src/flutter/impeller/entity/shaders/sdf_functions.glsl Outdated
Comment thread engine/src/flutter/impeller/entity/shaders/sdf_utils.glsl Outdated
@github-actions github-actions Bot removed the CICD Run CI/CD label May 28, 2026
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@walley892 walley892 requested a review from gaaclarke May 28, 2026 02:19
Comment thread engine/src/flutter/impeller/entity/contents/complex_rse_contents.h Outdated
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lgtm, thanks!

@github-actions github-actions Bot removed the CICD Run CI/CD label May 28, 2026
@walley892 walley892 added CICD Run CI/CD autosubmit Merge PR when tree becomes green via auto submit App labels May 28, 2026
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auto-submit Bot commented May 28, 2026

autosubmit label was removed for flutter/flutter/186434, because The base commit of the PR is older than 7 days and can not be merged. Please merge the latest changes from the main into this branch and resubmit the PR.

@walley892 walley892 added CICD Run CI/CD autosubmit Merge PR when tree becomes green via auto submit App and removed CICD Run CI/CD labels May 28, 2026
@auto-submit auto-submit Bot added this pull request to the merge queue May 28, 2026
Merged via the queue into flutter:master with commit c7b914a May 29, 2026
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auto-submit Bot pushed a commit to flutter/packages that referenced this pull request May 29, 2026
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