Sandbox::https://github.com/visgl/deck.gl/pull/10582

chrisgervang · 2026-08-21T23:00:37Z

Stack position: Part 4 of 6; base #10581.

Goal

Make dash phase a semantic choice: restart at rendered-segment boundaries or continue across the complete normalized path independently of tessellation.

Changes

Add optional constructor option dashMode: 'segment' | 'path'; segment behavior remains the default.
Build on the existing-options typing cleanup merged in fix(extensions): make PathStyle options optional #10616; this layer only adds dashMode to that public options surface.
Keep highPrecisionDash as a deprecated alias, with an explicit dashMode taking precedence.
Preserve the scalar public getDashOffsets while storing private vec2 [phase, totalLength] metrics for path mode.
Compose dashJustified with both phase domains and bound the solid interval when a complete path is shorter than the requested pattern.
Synchronize PathStyle-owned attributes and model layouts for same-ID segment → path → segment changes.
Update the dash-styles test app to exercise both semantic modes without forcing layer recreation.
Add render and unit coverage for constructor resolution, live mode changes, and all four mode/justification combinations.
Own the consolidated Stable dash patterns for PathStyleExtension RFC. It specifies both dashMode and the following dashUnits layer once; feat(extensions): add dashUnits #10583 inherits it byte-for-byte and has no effective RFC delta.

Benchmark results

Apple M1 Max/ANGLE Metal/WebGL2, 3840×2160, 20 samples at production head fc836ab9e5. Subsequent inherited fixes correct rounded-cap AA composition, limit the remapped rounded-corner/body intersection to PATH_STYLE_OFFSET shader variants, and preserve both phase and visible cap/joint bounds for camera-clipped billboards. This benchmark uses flat Orthographic paths with square caps and antialiasing: false, so the AA and billboard-clipping branches do not execute. The inherited bounds fix adds one dash-only varying, so the table remains the closest measured reference rather than a post-fix A/B.

Workload	Plain	Segment mode	Path mode	Offset only
100K sparse 1 px strokes	2.390	2.767	2.750	2.444
256 overlapping 64 px strokes	0.459	0.663	0.682	0.480

Path mode is within measurement noise of segment mode in the sparse pass and adds 0.019 ms (about 2.9%) beyond segment mode in the overdraw-heavy pass. The production normalized CPU updater is approximately 3.8 ms for a 100,000-segment path on this hardware; it runs only when path-continuous phase is requested.

The render matrix measures the intended semantic change: segment-mode density periods are 43.4/43.4/43.4/55.4 px before becoming visually solid, while path mode stays 43.4 px across the tested densities; whole-path justification produces a consistent 42.4 px fitted period.

Validation

Focused PathStyle and analytic-AA tests passed 27/27, covering constructor/API compatibility, same-ID topology, normalized metrics, short justification, and offset-bound rescaling.
Focused WebGL dash render suite passed 34 tests with one intentional backend-selection skip.
The inherited no-MSAA clipped-composition fixture passes and its golden is byte-identical to feat(extensions): prefilter dash coverage #10581.
The consolidated RFC is byte-identical in the synchronized release layers feat(extensions): add dashUnits #10583 and docs(extensions): PathStyleExtension reference for dashMode and dashUnits #10584.
Required GitHub checks and automated reviews are tracked on the current head.

Note

Medium Risk
Touches PathLayer dash GLSL, CPU tessellation metrics, and attribute topology on extension updates—visible rendering changes are possible, but defaults preserve segment mode and legacy highPrecisionDash behavior.

Overview
Introduces dashMode: 'segment' | 'path' on PathStyleExtension so dash phase can restart at each rendered segment (default, backward compatible) or stay continuous across tessellation, Globe cuts, and dense polylines. highPrecisionDash is deprecated in favor of explicit dashMode: 'path', with explicit mode winning when both are set.

Path-continuous mode stores instanceDashOffsets as a vec2 [distance along path, total length], drives HIGH_PRECISION_DASH from dashMode, and dashJustified now fits one period over the whole path in path mode (with solid length clamped on short runs). Shaders reduce phase modulo the active period in the vertex stage for long paths and reconcile offset widening with justified path phase.

synchronizeAttributes adds/removes extension attributes and refreshes model buffer layouts when the extension changes on a same-ID layer, enabling live segment ↔ path toggles without recreating layers. Exports DashMode; the dash-styles app and render/unit tests cover constructor resolution, mode × justification, and live topology changes. Adds the v9.4 path-dash RFC (also describes upcoming dashUnits; not implemented in this diff).

^{Reviewed by Cursor Bugbot for commit c778a17. Bugbot is set up for automated code reviews on this repo. Configure here.}

coveralls · 2026-08-21T23:09:04Z

coverage: 82.391% (+0.05%) from 82.346% — claude/deck-gl-path-dashing-2jnq8i-4 into master

greptile-apps · 2026-08-21T23:19:46Z

Greptile Summary

The PR adds segment- and whole-path dash phase modes while preserving compatibility with highPrecisionDash.

Exports the new DashMode option and resolves constructor aliases and defaults.
Synchronizes extension-owned attributes and model layouts during live mode changes.
Adds whole-path justification and path-length-aware shader phase calculations.
Expands unit, render, demo, golden-image, and RFC coverage.

Confidence Score: 5/5

The PR appears safe to merge.

No blocking failure remains.

Important Files Changed

Filename	Overview
modules/extensions/src/path-style/path-style-extension.ts	Adds dash-mode option resolution, path metrics, and attribute/model synchronization for live mode transitions.
modules/extensions/src/path-style/shaders.glsl.ts	Implements path-length-aware phase reduction and whole-path dash justification.
modules/extensions/src/index.ts	Exports the new public DashMode type.
test/modules/extensions/path.spec.ts	Covers option compatibility, normalized metrics, justification, and live attribute topology changes; the prior naming concern is resolved.
test/render/test-cases/path-dash.spec.ts	Expands visual coverage across dash modes and justification combinations.
dev-docs/RFCs/v9.4/path-dash-rfc.md	Documents the phase-domain API, compatibility behavior, implementation model, and limitations.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart LR
  A[PathStyleExtension options] --> B{dashMode}
  B -->|segment| C[Segment-local phase]
  B -->|path| D[CPU path metrics]
  D --> E[Phase and total length attribute]
  C --> F{dashJustified}
  E --> F
  F -->|off| G[Requested dash period]
  F -->|on| H[Fit period to active run]
  G --> I[Dash shader output]
  H --> I

_{Reviews (39): Last reviewed commit: "Merge #10581 from master" | Re-trigger Greptile}

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…ension Adds a render-test matrix and an interactive app for PathStyleExtension dashing, covering segment density, dash arrays, corners, zoom levels, device pixel ratio, 3D elevation and billboard/flat parity. The golden images record current behavior, defects included, so that subsequent work shows up as a direct image diff. Measured from these goldens with getDashArray [4, 5]: - Six strips drawing the identical straight line diverge purely by vertex count. 1, 2 and 4 segments dash correctly at a 43.4px period, 12 segments drifts to 55.4px, and 40 and 120 segments render fully solid. Dash phase restarts at every vertex, so once a segment is shorter than one dash period nothing is discarded. - dashJustified collapses the same way; justification is also per segment. - highPrecisionDash renders all six strips identically and correctly, confirming the continuous-arclength mechanism works and is merely opt-in. - billboard: true combined with highPrecisionDash is broken: the same geometry renders solid when dense and at a 52.0px period, 1.5x too long, when sparse, against 34.8px for the flat copy. - Dash length grows along paths that climb in Z, because the CPU accumulates 3D distance while the shader coordinate measures 2D. No source changes. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_014GipN1niYRgRuLVat2wujw

# Conflicts: # modules/extensions/src/path-style/path-style-extension.ts # modules/extensions/src/path-style/shaders.glsl.ts

# Conflicts: # modules/extensions/src/path-style/shaders.glsl.ts # test/modules/extensions/path.spec.ts

# Conflicts: # test/render/golden-images/path-dash-clipped-composition.png

# Conflicts: # test/render/test-cases/path-dash.spec.ts

# Conflicts: # modules/extensions/src/path-style/path-style-extension.ts # modules/extensions/src/path-style/shaders.glsl.ts # test/modules/extensions/path.spec.ts # test/render/test-cases/path-dash.spec.ts

chrisgervang marked this pull request as ready for review August 21, 2026 23:15

greptile-apps Bot reviewed Aug 21, 2026

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Comment thread test/modules/extensions/path.spec.ts Resolved

cursor Bot reviewed Aug 21, 2026

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Comment thread modules/extensions/src/path-style/shaders.glsl.ts Resolved

Pessimistress reviewed Aug 21, 2026

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Comment thread test/render/test-cases/path-dash.spec.ts Resolved

Pessimistress approved these changes Aug 21, 2026

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chrisgervang force-pushed the claude/deck-gl-path-dashing-2jnq8i-4 branch from 7ee028e to 62d32c2 Compare August 22, 2026 00:59

chrisgervang force-pushed the claude/deck-gl-path-dashing-2jnq8i-4 branch from 62d32c2 to 1967991 Compare August 22, 2026 01:05

chrisgervang force-pushed the claude/deck-gl-path-dashing-2jnq8i-4 branch from 1967991 to 72e53a0 Compare August 22, 2026 01:09

chrisgervang force-pushed the claude/deck-gl-path-dashing-2jnq8i-4 branch 2 times, most recently from 2556db1 to e0a52ed Compare August 22, 2026 22:00

cursor Bot reviewed Aug 22, 2026

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Comment thread modules/extensions/src/path-style/shaders.glsl.ts Resolved

chrisgervang force-pushed the claude/deck-gl-path-dashing-2jnq8i-4 branch from e0a52ed to c82aab9 Compare August 22, 2026 22:15

claude and others added 4 commits August 22, 2026 15:28

test: recreate dash layers when dashMode changes

ed5d48c

test(extensions): add default dash path variants

75c62a3

test(extensions): isolate 3D dash arclength

4a870d7

chrisgervang force-pushed the claude/deck-gl-path-dashing-2jnq8i-4 branch from c82aab9 to 4464687 Compare August 22, 2026 22:34

chrisgervang force-pushed the claude/deck-gl-path-dashing-2jnq8i-4 branch from 4464687 to 2de6726 Compare August 23, 2026 19:44

test(extensions): cover pitched rounded billboard dashes

18fa198

chrisgervang force-pushed the claude/deck-gl-path-dashing-2jnq8i-4 branch from 2de6726 to d5d0ac6 Compare August 24, 2026 00:05

chrisgervang and others added 25 commits August 30, 2026 19:14

Merge current master

1a022ca

Merge current options prerequisite

a4d762a

Merge current PathStyle parent

52d86fa

Merge current PathStyle parent

c51c744

Merge branch 'master' into claude/deck-gl-path-dashing-2jnq8i-2

b0f0101

Merge current master

659d30f

fix(path-layer): preserve clipped dash joint bounds

85f58ab

refactor(extensions): clarify dash metric invalidation

c38672a

Merge updated dash metric layer

bdf94da

Merge updated analytic dash coverage

6a346a5

# Conflicts: # modules/extensions/src/path-style/path-style-extension.ts # modules/extensions/src/path-style/shaders.glsl.ts

fix(extensions): rescale offset dash bounds

50f3053

Merge offset dash bounds fix

db34f4c

Merge offset dash bounds fix

1b9eb77

# Conflicts: # modules/extensions/src/path-style/shaders.glsl.ts # test/modules/extensions/path.spec.ts

test(render): baseline clipped PathStyle composition

d8905ee

Merge clipped PathStyle render baseline

d7dec88

test(render): capture clipped dash arclength fixes

1239863

Merge clipped PathStyle arclength baseline

9296f4c

test(render): capture clipped dash analytic coverage

455fb3b

Merge clipped PathStyle analytic baseline

dd15b26

Merge clipped PathStyle render prerequisite

088844b

# Conflicts: # test/render/golden-images/path-dash-clipped-composition.png

Merge clipped PathStyle render prerequisite

181c3d0

Merge clipped PathStyle render prerequisite

50915ef

test(render): document PathStyle dash expectations

5c51ecc

Merge updated PathStyle arclength parent

3f583e7

Merge updated analytic coverage parent

9769819

# Conflicts: # test/render/test-cases/path-dash.spec.ts

Base automatically changed from claude/deck-gl-path-dashing-2jnq8i-3 to master September 1, 2026 02:10

chrisgervang commented Sep 2, 2026

View reviewed changes

Comment thread modules/layers/src/path-layer/path-layer.ts Resolved

Merge #10581 from master

c778a17

# Conflicts: # modules/extensions/src/path-style/path-style-extension.ts # modules/extensions/src/path-style/shaders.glsl.ts # test/modules/extensions/path.spec.ts # test/render/test-cases/path-dash.spec.ts

chrisgervang merged commit 047126b into master Sep 2, 2026
8 checks passed

chrisgervang deleted the claude/deck-gl-path-dashing-2jnq8i-4 branch September 2, 2026 04:04

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feat(extensions): add dashMode and whole-path justification - #10582

feat(extensions): add dashMode and whole-path justification#10582
chrisgervang merged 137 commits into
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Confidence Score: 5/5

Important Files Changed

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