Skip to content

Reverts "[Flutter GPU] Add explicit draw counts (#186639)"#187170

Merged
cbracken merged 1 commit into
masterfrom
revert_c5190fa1f77db2d32df438a5aa77a1518ba8cca1
May 27, 2026
Merged

Reverts "[Flutter GPU] Add explicit draw counts (#186639)"#187170
cbracken merged 1 commit into
masterfrom
revert_c5190fa1f77db2d32df438a5aa77a1518ba8cca1

Conversation

@auto-submit

@auto-submit auto-submit Bot commented May 27, 2026 •
edited by cbracken
Loading

Copy link
Copy Markdown
Contributor

Reverts: #186639

Initiated by: cbracken

Reason for revert: doesn't compile on mac, or Linux.

Mac:

../../flutter/testing/dart/gpu_shader_reload_test.dart:64:36: Error: Too many positional arguments: 1 allowed, but 2 found.
Try removing the extra positional arguments.
  state.renderPass.bindVertexBuffer(
                                   ^
../../flutter/testing/dart/gpu_shader_reload_test.dart:72:24: Error: Too few positional arguments: 1 required, 0 given.
  state.renderPass.draw();

Linux:

[5064/6842] ACTION //flutter/testing/dart:compile_gpu_shader_reload_test.dart(//build/toolchain/linux:clang_x64)
FAILED: gen/gpu_shader_reload_test.dart.dill 
vpython3 ../../../build/gn_run_binary.py ../../../flutter/prebuilts/linux-x64/dart-sdk/bin/dartaotruntime /b/s/w/ir/cache/builder/engine/src/out/ci/host_release_benchmarks/gen/frontend_server_aot.dart.snapshot -DkFlutterSrcDirectory=/b/s/w/ir/cache/builder/engine/src/flutter -DkFlutterBuildDirectory=/b/s/w/ir/cache/builder/engine/src/out/ci/host_release_benchmarks/gen -DkSkiaGoldWorkDirectory=/b/s/w/ir/cache/builder/engine/src/out/ci/host_release_benchmarks/gen/skia_gold_gpu_shader_reload_test.dart --packages /b/s/w/ir/cache/builder/engine/src/flutter/.dart_tool/package_config.json --sdk-root flutter_patched_sdk --target=flutter --depfile gen/gpu_shader_reload_test.dart.dill.d --output-dill gen/gpu_shader_reload_test.dart.dill ../../../flutter/testing/dart/gpu_shader_reload_test.dart
Command failed: ./../../../flutter/prebuilts/linux-x64/dart-sdk/bin/dartaotruntime /b/s/w/ir/cache/builder/engine/src/out/ci/host_release_benchmarks/gen/frontend_server_aot.dart.snapshot -DkFlutterSrcDirectory=/b/s/w/ir/cache/builder/engine/src/flutter -DkFlutterBuildDirectory=/b/s/w/ir/cache/builder/engine/src/out/ci/host_release_benchmarks/gen -DkSkiaGoldWorkDirectory=/b/s/w/ir/cache/builder/engine/src/out/ci/host_release_benchmarks/gen/skia_gold_gpu_shader_reload_test.dart --packages /b/s/w/ir/cache/builder/engine/src/flutter/.dart_tool/package_config.json --sdk-root flutter_patched_sdk --target=flutter --depfile gen/gpu_shader_reload_test.dart.dill.d --output-dill gen/gpu_shader_reload_test.dart.dill ../../../flutter/testing/dart/gpu_shader_reload_test.dart
exitCode: 254
result 341449f6-a0e5-4e2b-8f52-4cab34a8338f
../../../flutter/testing/dart/gpu_shader_reload_test.dart:64:36: Error: Too many positional arguments: 1 allowed, but 2 found.
Try removing the extra positional arguments.
  state.renderPass.bindVertexBuffer(
                                   ^
../../../flutter/testing/dart/gpu_shader_reload_test.dart:72:24: Error: Too few positional arguments: 1 required, 0 given.
  state.renderPass.draw();
                       ^

Original PR Author: bdero

Reviewed By: {walley892}

This change reverts the following previous change:
Moves the vertex and index count off the buffer-binding calls and onto the draw call.

A simple (breaking) change that fixes a very silly design flaw that I built into the API near the very beginning. Moves Flutter GPU draws towards a design that matches virtually all modern graphics APIs, including today's Impeller!
Now is the right time to make changes like this to Flutter GPU, since the API is not yet considered stable.

Before, bindVertexBuffer and bindIndexBuffer each took a count, and a single argument-less draw() guessed vertex versus index based on whether an index buffer happened to be bound.

Sooooo many reasons this was the wrong design:

  • Wrong object. A draw count belongs on the draw, not on a buffer binding.
  • Implicit kind. Indexed vs. non-indexed was inferred from what happened to be bound, not stated.
  • Colliding counts. Vertex and index counts shared one field; the vertex count was dropped when an index buffer was bound.
  • Slot-0-only. The count came from vertex slot 0; values on other slots were silently ignored.
  • Opaque draws. draw() told you nothing; you had to trace every bind to know what it drew.
  • Sticky state. The count leaked across draws in a pass.
  • Redundant re-binds. Changing only the count forced re-binding the buffer.
  • No room to grow. Nowhere natural for per-draw params like instanceCount or baseVertex.
  • Unconventional. WebGPU, Vulkan, Metal, and D3D all put counts on the draw.
  • Late errors. Bad counts failed at draw() time, far from the mistaken line.

Now:

  • bindVertexBuffer and bindIndexBuffer only bind buffers.
  • draw(vertexCount) does a non-indexed draw.
  • drawIndexed(indexCount) does an indexed draw.

Instanced draws can be landed later via draw and drawIndexed gaining an instanceCount parameter later on, assuming the Impeller-side instancing support in #186653 lands.

Pre-launch Checklist

@auto-submit auto-submit Bot added the revert of Bot Only: Tracking label for bot. Tracks new revert of pull requests. label May 27, 2026
@github-actions github-actions Bot added engine flutter/engine related. See also e: labels. e: impeller Impeller rendering backend issues and features requests flutter-gpu team-fluttergpu Owned by Flutter GPU team labels May 27, 2026
@github-project-automation github-project-automation Bot moved this to 🤔 Needs Triage in Flutter GPU May 27, 2026
@cbracken cbracken added the emergency Jump the queue; land PR in front of all others; only use for emergencies label May 27, 2026
@flutter-dashboard

flutter-dashboard Bot commented May 27, 2026

Copy link
Copy Markdown

Detected the emergency label.

If you add the autosubmit label, the bot will wait until all presubmits pass but ignore the tree status, allowing fixes for tree breakages while still validating that they don't break any existing presubmits.

The "Merge" button is also unlocked. To bypass presubmits as well as the tree status, press the GitHub "Add to Merge Queue".

@auto-submit auto-submit Bot removed the revert of Bot Only: Tracking label for bot. Tracks new revert of pull requests. label May 27, 2026
@auto-submit

auto-submit Bot commented May 27, 2026

Copy link
Copy Markdown
Contributor Author

auto label is removed for flutter/flutter/187170, Failed to enqueue flutter/flutter/187170 with HTTP 400: Pull request 2 of 3 required status checks have not succeeded: 1 expected..

@cbracken cbracken enabled auto-merge May 27, 2026 13:33
@cbracken cbracken added the CICD Run CI/CD label May 27, 2026
@cbracken cbracken added this pull request to the merge queue May 27, 2026
Merged via the queue into master with commit c8f2f16 May 27, 2026
142 of 217 checks passed
@cbracken cbracken deleted the revert_c5190fa1f77db2d32df438a5aa77a1518ba8cca1 branch May 27, 2026 14:07
@github-project-automation github-project-automation Bot moved this from 🤔 Needs Triage to ✅ Done in Flutter GPU May 27, 2026
@engine-flutter-autoroll engine-flutter-autoroll mentioned this pull request May 27, 2026
Merged
auto-submit Bot pushed a commit to flutter/packages that referenced this pull request May 27, 2026
@engine-flutter-autoroll
Roll Flutter from f3a4b9897834 to c8f2f166323e (29 revisions) (#11795)
4b424d7 
flutter/flutter@f3a4b98...c8f2f16

2026-05-27 98614782+auto-submit[bot]@users.noreply.github.com Reverts "[Flutter GPU] Add explicit draw counts (#186639)" (flutter/flutter#187170)
2026-05-27 engine-flutter-autoroll@skia.org Roll Dart SDK from 7dcea971af6b to f3db7b7d9801 (2 revisions) (flutter/flutter#187144)
2026-05-27 bdero@google.com [Flutter GPU] Add explicit draw counts (flutter/flutter#186639)
2026-05-27 engine-flutter-autoroll@skia.org Roll Skia from f9db7748563e to fa944af10f91 (1 revision) (flutter/flutter#187139)
2026-05-27 bdero@google.com [Flutter GPU] Flutter GPU ShaderLibrary in-place reload for shader hot reload (flutter/flutter#186793)
2026-05-27 engine-flutter-autoroll@skia.org Roll Skia from a692cbf38952 to f9db7748563e (8 revisions) (flutter/flutter#187135)
2026-05-27 burak.karahan@mail.ru Use local semantics tester in Material button tests (flutter/flutter#186667)
2026-05-27 rmolivares@renzo-olivares.dev Filter out `a: text input` from `team-framework` PR triage  (flutter/flutter#187129)
2026-05-27 bkonyi@google.com [Engine] Fix silent buffer mismatch bug in FML Win32 CommandLineFromPlatform (flutter/flutter#187120)
2026-05-27 srawlins@google.com examples: Remove unused parameters (flutter/flutter#185819)
2026-05-27 116356835+AbdeMohlbi@users.noreply.github.com Remove another `String.valueOf` (flutter/flutter#186628)
2026-05-27 alex.medinsh@gmail.com Print trace when skipping flavor-specific and platform-specific assets (flutter/flutter#187045)
2026-05-26 adilhanney@disroot.org Fix `InteractiveViewer` memory leak from undisposed `CurvedAnimation`s (flutter/flutter#185826)
2026-05-26 meylis@divine.video Fix AccessibilityBridge startup crash on vendor-modified Android (flutter/flutter#184630)
2026-05-26 keertip@users.noreply.github.com Update data driven fixes docs (flutter/flutter#186217)
2026-05-26 ahmedsameha1@gmail.com Add more 0x0 size tests part10 (flutter/flutter#186201)
2026-05-26 46920873+gabrimatic@users.noreply.github.com Disable spell check for obscured text (flutter/flutter#186329)
2026-05-26 chris@bracken.jp [iOS] Migrate VSyncClient and DisplayLinkManager to Swift (flutter/flutter#187001)
2026-05-26 bkonyi@google.com [flutter_tools, devicelab] Add safety filesystem guard to tests (flutter/flutter#186748)
2026-05-26 engine-flutter-autoroll@skia.org Roll Fuchsia Linux SDK from Itd2Jq_ZIABH2rW7B... to k9EizfEGJO4WwQN9-... (flutter/flutter#187115)
2026-05-26 engine-flutter-autoroll@skia.org Roll Dart SDK from 00e625453c43 to 7dcea971af6b (1 revision) (flutter/flutter#187117)
2026-05-26 rmacnak@google.com Remove use of deprecated copy_trees. (flutter/flutter#187091)
2026-05-26 15619084+vashworth@users.noreply.github.com Use resolved implementation plugins with SwiftPM (flutter/flutter#187097)
2026-05-26 engine-flutter-autoroll@skia.org Roll Skia from 27a819894f7c to a692cbf38952 (3 revisions) (flutter/flutter#187109)
2026-05-26 engine-flutter-autoroll@skia.org Roll Packages from 69cf959 to fc795e5 (4 revisions) (flutter/flutter#187114)
2026-05-26 mvincentong@gmail.com Handle simctl process exceptions during discovery (flutter/flutter#186501)
2026-05-26 mvincentong@gmail.com Clarify precache enabled platforms help (flutter/flutter#186878)
2026-05-26 bkonyi@google.com [tool] Refactor artifacts.dart to use enhanced enums and reduce duplication (flutter/flutter#187063)
2026-05-26 jason-simmons@users.noreply.github.com Build script updates for syncing engine sources and building artifacts on linux-arm64 (flutter/flutter#186917)

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/flutter-packages
Please CC boetger@google.com,stuartmorgan@google.com on the revert to ensure that a human
is aware of the problem.

To file a bug in Packages: 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
@bdero bdero mentioned this pull request May 27, 2026
Merged
10 tasks
mboetger pushed a commit to mboetger/flutter that referenced this pull request May 27, 2026
@bdero
[Flutter GPU] Add explicit draw counts (reland) (flutter#187192)
d0d06b2 
Relands flutter#186639, which was reverted in flutter#187170.

The original PR landed clean, but broke the macOS and Linux builds
because `engine/src/flutter/testing/dart/gpu_shader_reload_test.dart`
(added concurrently by flutter#186793, which was in the merge queue at the same
time) still called the old `bindVertexBuffer(view, count)` / `draw()`
API. This reland is identical to flutter#186639 plus a one-spot migration of
that test to `bindVertexBuffer(view)` + `draw(3)`.

---

Moves the vertex and index count off the buffer-binding calls and onto
the draw call.

A simple (breaking) change that fixes a very silly design flaw that I
built into the API near the very beginning. Moves Flutter GPU draws
towards a design that matches virtually all modern graphics APIs,
including today's Impeller! Now is the right time to make changes like
this to Flutter GPU, since the API is not yet considered stable.

Before, `bindVertexBuffer` and `bindIndexBuffer` each took a count, and
a single argument-less `draw()` guessed vertex versus index based on
whether an index buffer happened to be bound.

Sooooo many reasons this was the wrong design:

- **Wrong object.** A draw count belongs on the draw, not on a buffer
binding.
- **Implicit kind.** Indexed vs. non-indexed was inferred from what
happened to be bound, not stated.
- **Colliding counts.** Vertex and index counts shared one field; the
vertex count was dropped when an index buffer was bound.
- **Slot-0-only.** The count came from vertex slot 0; values on other
slots were silently ignored.
- **Opaque draws.** `draw()` told you nothing; you had to trace every
bind to know what it drew.
- **Sticky state.** The count leaked across draws in a pass.
- **Redundant re-binds.** Changing only the count forced re-binding the
buffer.
- **No room to grow.** Nowhere natural for per-draw params like
`instanceCount` or `baseVertex`.
- **Unconventional.** WebGPU, Vulkan, Metal, and D3D all put counts on
the draw.
- **Late errors.** Bad counts failed at `draw()` time, far from the
mistaken line.

Now:
- `bindVertexBuffer` and `bindIndexBuffer` only bind buffers.
- `draw(vertexCount)` does a non-indexed draw.
- `drawIndexed(indexCount)` does an indexed draw.

Instanced draws can be landed later via `draw` and `drawIndexed` gaining
an `instanceCount` parameter later on, assuming the Impeller-side
instancing support in flutter#186653 lands.

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [AI contribution guidelines] and understand my
responsibilities, or I am not using AI tools.
- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [x] I signed the [CLA].
- [x] I listed at least one issue that this PR fixes in the description
above.
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [x] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [ ] All existing and new tests are passing.

<!-- Links -->
[Contributor Guide]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview
[AI contribution guidelines]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#ai-contribution-guidelines
[Tree Hygiene]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md
[test-exempt]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests
[Flutter Style Guide]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md
[Features we expect every widget to implement]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement
[CLA]: https://cla.developers.google.com/
[flutter/tests]: https://github.com/flutter/tests
[breaking change policy]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes
[Discord]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Chat.md
[Data Driven Fixes]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md
creatorpiyush pushed a commit to creatorpiyush/packages that referenced this pull request Jun 10, 2026
@engine-flutter-autoroll
Roll Flutter from f3a4b9897834 to c8f2f166323e (29 revisions) (flutte…
565c597 
…r#11795)

flutter/flutter@f3a4b98...c8f2f16

2026-05-27 98614782+auto-submit[bot]@users.noreply.github.com Reverts "[Flutter GPU] Add explicit draw counts (#186639)" (flutter/flutter#187170)
2026-05-27 engine-flutter-autoroll@skia.org Roll Dart SDK from 7dcea971af6b to f3db7b7d9801 (2 revisions) (flutter/flutter#187144)
2026-05-27 bdero@google.com [Flutter GPU] Add explicit draw counts (flutter/flutter#186639)
2026-05-27 engine-flutter-autoroll@skia.org Roll Skia from f9db7748563e to fa944af10f91 (1 revision) (flutter/flutter#187139)
2026-05-27 bdero@google.com [Flutter GPU] Flutter GPU ShaderLibrary in-place reload for shader hot reload (flutter/flutter#186793)
2026-05-27 engine-flutter-autoroll@skia.org Roll Skia from a692cbf38952 to f9db7748563e (8 revisions) (flutter/flutter#187135)
2026-05-27 burak.karahan@mail.ru Use local semantics tester in Material button tests (flutter/flutter#186667)
2026-05-27 rmolivares@renzo-olivares.dev Filter out `a: text input` from `team-framework` PR triage  (flutter/flutter#187129)
2026-05-27 bkonyi@google.com [Engine] Fix silent buffer mismatch bug in FML Win32 CommandLineFromPlatform (flutter/flutter#187120)
2026-05-27 srawlins@google.com examples: Remove unused parameters (flutter/flutter#185819)
2026-05-27 116356835+AbdeMohlbi@users.noreply.github.com Remove another `String.valueOf` (flutter/flutter#186628)
2026-05-27 alex.medinsh@gmail.com Print trace when skipping flavor-specific and platform-specific assets (flutter/flutter#187045)
2026-05-26 adilhanney@disroot.org Fix `InteractiveViewer` memory leak from undisposed `CurvedAnimation`s (flutter/flutter#185826)
2026-05-26 meylis@divine.video Fix AccessibilityBridge startup crash on vendor-modified Android (flutter/flutter#184630)
2026-05-26 keertip@users.noreply.github.com Update data driven fixes docs (flutter/flutter#186217)
2026-05-26 ahmedsameha1@gmail.com Add more 0x0 size tests part10 (flutter/flutter#186201)
2026-05-26 46920873+gabrimatic@users.noreply.github.com Disable spell check for obscured text (flutter/flutter#186329)
2026-05-26 chris@bracken.jp [iOS] Migrate VSyncClient and DisplayLinkManager to Swift (flutter/flutter#187001)
2026-05-26 bkonyi@google.com [flutter_tools, devicelab] Add safety filesystem guard to tests (flutter/flutter#186748)
2026-05-26 engine-flutter-autoroll@skia.org Roll Fuchsia Linux SDK from Itd2Jq_ZIABH2rW7B... to k9EizfEGJO4WwQN9-... (flutter/flutter#187115)
2026-05-26 engine-flutter-autoroll@skia.org Roll Dart SDK from 00e625453c43 to 7dcea971af6b (1 revision) (flutter/flutter#187117)
2026-05-26 rmacnak@google.com Remove use of deprecated copy_trees. (flutter/flutter#187091)
2026-05-26 15619084+vashworth@users.noreply.github.com Use resolved implementation plugins with SwiftPM (flutter/flutter#187097)
2026-05-26 engine-flutter-autoroll@skia.org Roll Skia from 27a819894f7c to a692cbf38952 (3 revisions) (flutter/flutter#187109)
2026-05-26 engine-flutter-autoroll@skia.org Roll Packages from 69cf959 to fc795e5 (4 revisions) (flutter/flutter#187114)
2026-05-26 mvincentong@gmail.com Handle simctl process exceptions during discovery (flutter/flutter#186501)
2026-05-26 mvincentong@gmail.com Clarify precache enabled platforms help (flutter/flutter#186878)
2026-05-26 bkonyi@google.com [tool] Refactor artifacts.dart to use enhanced enums and reduce duplication (flutter/flutter#187063)
2026-05-26 jason-simmons@users.noreply.github.com Build script updates for syncing engine sources and building artifacts on linux-arm64 (flutter/flutter#186917)

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/flutter-packages
Please CC boetger@google.com,stuartmorgan@google.com on the revert to ensure that a human
is aware of the problem.

To file a bug in Packages: 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
via-guy pushed a commit to via-guy/flutter that referenced this pull request Jun 26, 2026
@auto-submit @via-guy
Reverts "[Flutter GPU] Add explicit draw counts (flutter#186639)" (fl…
9e14c51 
…utter#187170)

<!-- start_original_pr_link -->
Reverts: flutter#186639
<!-- end_original_pr_link -->
<!-- start_initiating_author -->
Initiated by: cbracken
<!-- end_initiating_author -->
<!-- start_revert_reason -->
Reason for reverting: doesn't compile on mac, or Linux.

Mac:
```
../../flutter/testing/dart/gpu_shader_reload_test.dart:64:36: Error: Too many positional arguments: 1 allowed, but 2 found.
Try removing the extra positional arguments.
  state.renderPass.bindVertexBuffer(
                                   ^
../../flutter/testing/dart/gpu_shader_reload_test.dart:72:24: Error: Too few positional arguments: 1 requ
<!-- end_revert_reason -->
<!-- start_original_pr_author -->
Original PR Author: bdero
<!-- end_original_pr_author -->

<!-- start_reviewers -->
Reviewed By: {walley892}
<!-- end_reviewers -->

<!-- start_revert_body -->
This change reverts the following previous change:
Moves the vertex and index count off the buffer-binding calls and onto the draw call.

A simple (breaking) change that fixes a very silly design flaw that I built into the API near the very beginning. Moves Flutter GPU draws towards a design that matches virtually all modern graphics APIs, including today's Impeller!
Now is the right time to make changes like this to Flutter GPU, since the API is not yet considered stable.

Before, `bindVertexBuffer` and `bindIndexBuffer` each took a count, and a single argument-less `draw()` guessed vertex versus index based on whether an index buffer happened to be bound.

Sooooo many reasons this was the wrong design:

- **Wrong object.** A draw count belongs on the draw, not on a buffer binding.
- **Implicit kind.** Indexed vs. non-indexed was inferred from what happened to be bound, not stated.
- **Colliding counts.** Vertex and index counts shared one field; the vertex count was dropped when an index buffer was bound.
- **Slot-0-only.** The count came from vertex slot 0; values on other slots were silently ignored.
- **Opaque draws.** `draw()` told you nothing; you had to trace every bind to know what it drew.
- **Sticky state.** The count leaked across draws in a pass.
- **Redundant re-binds.** Changing only the count forced re-binding the buffer.
- **No room to grow.** Nowhere natural for per-draw params like `instanceCount` or `baseVertex`.
- **Unconventional.** WebGPU, Vulkan, Metal, and D3D all put counts on the draw.
- **Late errors.** Bad counts failed at `draw()` time, far from the mistaken line.

Now:
- `bindVertexBuffer` and `bindIndexBuffer` only bind buffers.
- `draw(vertexCount)` does a non-indexed draw.
- `drawIndexed(indexCount)` does an indexed draw.

Instanced draws can be landed later via `draw` and `drawIndexed` gaining an `instanceCount` parameter later on, assuming the Impeller-side instancing support in flutter#186653 lands.

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined there for submitting PRs.
- [x] I read the [AI contribution guidelines] and understand my responsibilities, or I am not using AI tools.
- [x] I read the [Tree Hygiene] wiki page, which explains my responsibilities.
- [x] I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement].
- [x] I signed the [CLA].
- [x] I listed at least one issue that this PR fixes in the description above.
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] I added new tests to check the change I am making, or this PR is [test-exempt].
- [x] I followed the [breaking change policy] and added [Data Driven Fixes] where supported.
- [ ] All existing and new tests are passing.


<!-- Links -->
[Contributor Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview
[AI contribution guidelines]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#ai-contribution-guidelines
[Tree Hygiene]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md
[test-exempt]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests
[Flutter Style Guide]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md
[Features we expect every widget to implement]: https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement
[CLA]: https://cla.developers.google.com/
[flutter/tests]: https://github.com/flutter/tests
[breaking change policy]: https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes
[Discord]: https://github.com/flutter/flutter/blob/main/docs/contributing/Chat.md
[Data Driven Fixes]: https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md

<!-- end_revert_body -->

Co-authored-by: auto-submit[bot] <flutter-engprod-team@google.com>
via-guy pushed a commit to via-guy/flutter that referenced this pull request Jun 26, 2026
@bdero @via-guy
[Flutter GPU] Add explicit draw counts (reland) (flutter#187192)
b1bf03e 
Relands flutter#186639, which was reverted in flutter#187170.

The original PR landed clean, but broke the macOS and Linux builds
because `engine/src/flutter/testing/dart/gpu_shader_reload_test.dart`
(added concurrently by flutter#186793, which was in the merge queue at the same
time) still called the old `bindVertexBuffer(view, count)` / `draw()`
API. This reland is identical to flutter#186639 plus a one-spot migration of
that test to `bindVertexBuffer(view)` + `draw(3)`.

---

Moves the vertex and index count off the buffer-binding calls and onto
the draw call.

A simple (breaking) change that fixes a very silly design flaw that I
built into the API near the very beginning. Moves Flutter GPU draws
towards a design that matches virtually all modern graphics APIs,
including today's Impeller! Now is the right time to make changes like
this to Flutter GPU, since the API is not yet considered stable.

Before, `bindVertexBuffer` and `bindIndexBuffer` each took a count, and
a single argument-less `draw()` guessed vertex versus index based on
whether an index buffer happened to be bound.

Sooooo many reasons this was the wrong design:

- **Wrong object.** A draw count belongs on the draw, not on a buffer
binding.
- **Implicit kind.** Indexed vs. non-indexed was inferred from what
happened to be bound, not stated.
- **Colliding counts.** Vertex and index counts shared one field; the
vertex count was dropped when an index buffer was bound.
- **Slot-0-only.** The count came from vertex slot 0; values on other
slots were silently ignored.
- **Opaque draws.** `draw()` told you nothing; you had to trace every
bind to know what it drew.
- **Sticky state.** The count leaked across draws in a pass.
- **Redundant re-binds.** Changing only the count forced re-binding the
buffer.
- **No room to grow.** Nowhere natural for per-draw params like
`instanceCount` or `baseVertex`.
- **Unconventional.** WebGPU, Vulkan, Metal, and D3D all put counts on
the draw.
- **Late errors.** Bad counts failed at `draw()` time, far from the
mistaken line.

Now:
- `bindVertexBuffer` and `bindIndexBuffer` only bind buffers.
- `draw(vertexCount)` does a non-indexed draw.
- `drawIndexed(indexCount)` does an indexed draw.

Instanced draws can be landed later via `draw` and `drawIndexed` gaining
an `instanceCount` parameter later on, assuming the Impeller-side
instancing support in flutter#186653 lands.

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [AI contribution guidelines] and understand my
responsibilities, or I am not using AI tools.
- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [x] I signed the [CLA].
- [x] I listed at least one issue that this PR fixes in the description
above.
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [x] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [ ] All existing and new tests are passing.

<!-- Links -->
[Contributor Guide]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview
[AI contribution guidelines]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#ai-contribution-guidelines
[Tree Hygiene]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md
[test-exempt]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests
[Flutter Style Guide]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md
[Features we expect every widget to implement]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement
[CLA]: https://cla.developers.google.com/
[flutter/tests]: https://github.com/flutter/tests
[breaking change policy]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes
[Discord]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Chat.md
[Data Driven Fixes]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Reviewers

@fluttergithubbot fluttergithubbot fluttergithubbot approved these changes

Assignees

@cbracken cbracken

Labels

CICD Run CI/CD e: impeller Impeller rendering backend issues and features requests emergency Jump the queue; land PR in front of all others; only use for emergencies engine flutter/engine related. See also e: labels. flutter-gpu team-fluttergpu Owned by Flutter GPU team

Projects

Flutter GPU
Status: ✅ Done

Milestone

No milestone

Development

Successfully merging this pull request may close these issues.

2 participants

@fluttergithubbot @cbracken