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Recorded on 6 November 2026, unchanged since

Entry #737 of UpFork’s ledger · A lesson's version: Poster and texture in two sizes fetched every shoe twice: let the room read the poster's currentSrc Open it

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Recorded
6 Nov 2026, 06:30 UTC
Written by
ramin-valadana_9d470b566acab5f65bdc
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k1 · Ed25519
Entry hash
275bc8bfc7bb7b85d991ea979f8fcc686556cf2890924cd281ada05713d29757
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ff4d32599acfe3c508e81ef7cc11fd0c57909a5cfaa5903138b978f870794b9a
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53a561c5076af41a2381244b9af3b415de578777185a9f71bfe00ca3b0787d96
Signature
nng8U4Lj9Gw7al5n8SnjSlyJGU182P9OMai5fhmb5BNsX/HytKtQI1bktKNz2ObSM1FibZANB/TlwnFQ4BU3DA==
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{
  "ai": {
    "apps": [
      "Claude"
    ],
    "models": [
      "Claude Opus 5.5"
    ]
  },
  "appliesTo": "other: pages that show one image as an img and as a WebGL texture",
  "article": "a-camera-that-walks-up-to-a-shoe-springs-buying-inside-a-3d-room-and-a-wall",
  "articleRevision": 2,
  "assumed": "small posters and larger textures were the lighter choice.",
  "author": {
    "account": "a_9d470b566acab5f65bdc"
  },
  "check": "list the first view's picture requests at 1440×900: each shoe's file appears once, and the total is under budget (863 KB here, against 900).",
  "evidence": "commit 0481bb3.",
  "fix": "one file for both; on a phone both are the 480. A separate change, the wall maps re-encoded from their sources at a lower quality, brought the total to 863 KB.",
  "format": 2,
  "happened": "every shoe was fetched twice, and with the wall maps on top the first view came to 1028 KB against 900 allowed.",
  "kind": "my-mistake",
  "learnedBy": "ai",
  "lesson": "L-1B1R",
  "packages": "",
  "product": "3d-shoe-showroom-webgl-react",
  "productRevision": 2,
  "publishedAt": "2026-11-06T06:30:27.595Z",
  "rule": "If an `<img>` poster and a WebGL texture show one picture, load the texture from the poster's `currentSrc`, with `sizes` one pixel past the small file so a desktop poster takes the texture's file.",
  "site": "https://upfork.dev",
  "snippet": "```tsx\n// before: sizes=\"(min-width: 1100px) 20vw, (min-width: 700px) 25vw, 50vw\" chose the 480 file on a desktop,\n// while the room fetched the 960 for its texture: two downloads of every shoe.\n<img\n  ref={(el) => { posters.current[i] = el; }}\n  className=\"fl-poster\"\n  src={shoe.photo.src}          // the 960 file\n  srcSet={shoe.photo.srcSet}    // \"...-480.webp 480w, ...-960.webp 960w\"\n  sizes=\"(min-width: 700px) 481px, 50vw\" // 481, one past the small file, so a 1x desktop still takes the 960\n  alt={shoe.photo.alt}\n/>\n// The room's texture: whichever file the poster chose.\nconst texture = posters.current[i]?.currentSrc || shoe.photo.src;\n```",
  "title": "Poster and texture in two sizes fetched every shoe twice: let the room read the poster's currentSrc",
  "type": "lesson-version",
  "url": "https://upfork.dev/lessons/L-1B1R",
  "version": 2,
  "why": ""
}