CODAP-1509: draw and hit test point shapes in the PIXI renderer

[kswenson]

Draws the seven point shapes in the PIXI/WebGL renderer and hit tests against them. Fifth in the LEADS Point Shapes stack, on top of #2696.

Fixes CODAP-1509.

What was actually needed

Very little plumbing. Nothing in the style path branches on renderer type, so the work done for the canvas renderer already carries shapes to PIXI through the same setPointStyle and matchPointsToData calls — and point-shapes.ts is consumed unchanged, which is what it was built for. The texture cache needed no change either: its key is the whole style, which now carries the shape, so two shapes cannot collide on one texture.

Two things did need care.

Centering

A sprite draws its texture around its anchor, which for points is the middle of the texture. Left to size itself, a texture takes the bounds of the ink — and a triangle's ink is not centered on the point, because the shape sits on its center of area. Anchoring the middle of that box would draw a triangle low by about a third of its radius, reinstating in WebGL exactly the positional bias the canvas renderer was fixed for. At r=8 the offset is 2.9px for a triangle and 1.1px for a star; every other shape is symmetric and unaffected.

The texture is given an explicit frame centered on the point instead, sized by a new pointShapeSymmetricExtent. Circles keep the path they have always had, including sizing their own texture.

Hit testing, and a behavior change worth noticing

Sprites now carry a hitArea that tests the drawn shape, deferring to the same containment the canvas renderer uses so the two renderers agree on what counts as a hit. That matters because graphics acceleration is a user setting — the same document should not pick differently depending on it.

This also tightens picking for circles. Sprites previously had no hitArea at all, so they hit tested against the rectangle of their texture: a click up to about 1.4 radii from a point's center would select it. That stops. It is a fix rather than a regression, but it reaches every existing document, so it is worth a reviewer's attention rather than being buried.

Bars keep the rectangular test, which is what a bar is.

Scope

Behind the pointShapes feature flag, which gates the controls. Verified manually with graphics acceleration on, and with it toggled off and on to confirm the two renderers agree.

Not measured: texture churn with many shapes in play. The count stays bounded — shape and color are both functions of the same legend category — but cleanupUnusedTextures() still has its single call site in the ticker's idle branch.

🤖 Generated with Claude Code

[codecov]

Codecov Report

❌ Patch coverage is 97.91667% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 87.91%. Comparing base (7c1af50) to head (e8f1e90).

Files with missing lines	Patch %	Lines
...nents/data-display/renderer/pixi-point-renderer.ts	97.43%	1 Missing ⚠️

Additional details and impacted files

@@                        Coverage Diff                         @@
##           CODAP-1504-point-shapes-canvas    #2697      +/-   ##
==================================================================
+ Coverage                           87.89%   87.91%   +0.01%     
==================================================================
  Files                                 821      821              
  Lines                               47486    47527      +41     
  Branches                            12135    12039      -96     
==================================================================
+ Hits                                41738    41782      +44     
+ Misses                               5732     5729       -3     
  Partials                               16       16              

Flag	Coverage Δ
cypress	69.57% <63.63%> (+0.01%)	⬆️
jest	63.24% <95.83%> (+0.05%)	⬆️

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[cypress]

codap-v3    Run #12244

Run Properties:   Passed #12244  •  e8f1e90736: null

Project	codap-v3
Branch Review	CODAP-1509-point-shapes-pixi
Run status	Passed #12244
Run duration	09m 10s
Commit	e8f1e90736: null
Committer	null
View all properties for this run ↗︎

---

Test results
Failures	0
Flaky	1
Pending	82
Skipped	0
Passing	384
View all changes introduced in this branch ↗︎

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[kswenson]

Reviewing this stack — five PRs, each based on the one below it, merging bottom-up into leads-point-shapes:

PR	Story	What it is
#2691	CODAP-1506 (part 1)	Format palette restructure — structural, no shape behavior
#2692	CODAP-1505	Per-category shape storage — model only
#2693	CODAP-1506 (part 2)	The shape controls — UI
#2696	CODAP-1504	Canvas rendering and hit testing
#2697	CODAP-1509	PIXI/WebGL rendering and hit testing

CODAP-1506 is split across #2691 and #2693, so approving #2691 does not complete that story — it should not leave code review until #2693 is approved too. The other three map one-to-one.

Nothing here is superseded — this is the top of the stack.

Worth your attention:

• The centering fix. This is the one that would have shipped as a subtle wrong-looking plot rather than an obvious break: a triangle drawn ~2.9px low at r=8, which reads as "the points are slightly off" rather than as a bug in shape rendering.
• The hit-testing change tightens picking for circles, in every existing document — sprites previously had no hitArea at all and tested against their texture's rectangle. Called out in the description; I'd rather it be argued about than slip through.
• point-shapes.ts is consumed unchanged from CODAP-1504: draw and hit test point shapes in the canvas renderer #2696. If something about the geometry looks wrong here, it belongs on that PR.

Out of scope by design, each with a ticket: legend keys carrying the shape (CODAP-1507), the residual plot (CODAP-1526).