# The weight of a moment.

Independent article case study. Domain: website consumer / Design Engineering presentation.

A deterministic bounce evaluator maps the playhead to separate height, squash and color tracks. The impact keyframe is editable; the graph and sphere use the same evaluated values.

## Attribution and evidence

Studied: [Animating a 3D Scene with Spline’s New Timeline Tool](https://tympanus.net/codrops/2025/11/05/animating-a-3d-scene-with-splines-new-timeline-tool/), Maksim Borisov. Article SHA-256: adf29c6579388f41a6edaa2d77e94abfd5f64fe5142fc188c1495bb8bd6673fd. Analysis SHA-256: ce77cbdfe15008e305407081361c09d08cd5b8118b04f753a11a2a649e7cf06f. Source revision: 213d64f3f0a508dfac483f730c2ccce65a148b6654b803c58f3cd53dbc6657ef. The revision hashes the article/analysis hashes, the analyst principle and code-block evidence references; it identifies studied evidence, not a claim that the original demo executes.

Original acquisition: unresolved. Original license: unverified. originalSourceAcquired: false. Public Spline scene/community links were identified, but no original scene export and applicable scene license were acquired. The article has a timeline workflow but no code blocks.

No original article prose, code, artwork, source project or screenshot is distributed here. The authored-code MIT notice applies only to the independent implementation. The article supplies no code blocks; derive behavior from the timeline/graph-editor explanation. Do not label the result a recovered Spline scene.

## Initial state and controls

A sphere falls, compresses, and recovers. Scrub a single playhead while height, deformation and color follow their own tracks.

The page starts stationary. Play motion, where present, advances this study’s presentation until paused; text, bounce, portrait, orbit, strand and mascot motion loops, while the event composer stops at its endpoint. Scroll studies advance through ordinary document scroll or their chapter buttons. Static view stops time-based motion; manual controls still inspect values. The three scroll studies instead show every chapter in ordinary reading flow. Pointer parallax centers its decorative layers.

Initial control values:

| Control key | Value |
| --- | --- |
| phase | 28 |
| impact | 52 |
| squash | 35 |
| curve | gravity |
| duration | 2.4 |

## Running and editing

Open index.html directly. It contains all runtime code and visuals and needs no package install, account, network, remote asset or browser-origin storage. Edit its inline style and script to change the downloaded page. styles.css and script.js are reference copies of the inline source; changing those copies alone does not change the running page. Repository regeneration overwrites index.html and all generated copies, including any manual edits. Keep a separate copy when editing a download. The repository authoring modules in vendor/codrops-article-studies/scenes-*.mjs and runtime.mjs regenerate these copies through node scripts/build-codrops-article-studies.mjs. Repository regeneration also needs the private source evidence; downloaded-page execution does not.

## Verification boundary

This generation passed the captured article/analysis hash checks, exact ID membership, local canonical Markdown anchor/hash checks, implementation-symbol checks, JavaScript parsing, semantic main/title counts, duplicate-ID checks and runtime URL/storage exclusion. The manifest codeFiles entries identify every emitted file by SHA-256. Each code symbol is a searchable named function, not a claimed executed call trace. Proposed checks are in KNOWLEDGE.json. runtime_verified: false. SG artifact capture proves only a recorded initial render; no interactive runtime, keyboard, accessibility, comfort or performance result is claimed.

Manual Chrome interaction is blocked by extension UI in this session. No alternate browser-control route was used. Preview sizing is native responsive width. Initial-render captures are tracked separately at site/artifacts/full-import/preview-posters/index.json and site/artifacts/full-import/preview-posters/visual-review.json in the repository. No capture receipt is bundled with this download. The bounded initial-render matrix requests all 21 studies at 320 pixels and three representative studies at 1280 pixels; the separate poster surface is 640 × 420. The authored CSS also adapts at 375 and 768 pixels, without claiming those widths were captured. A width request does not mean that capture exists or passed. Motion starts on explicit playback; system reduced motion and the Static view switch stop it.

consumer_reference: consumer-reference/agent-native/registry.json