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Recorded on 5 November 2026, unchanged since

Entry #717 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
5 Nov 2026, 22:02 UTC
Written by
ramin-valadana_9d470b566acab5f65bdc
Signed with
k1 · Ed25519
Entry hash
fbb9e9a33c6c63117e7f9e075eaca9ee8c03bb85f051fea134f2e9d80aa86904
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0fb405a549244cda1e3ada599abdeb409bb08de18c828d83d48733520fd8783c
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2dd2db37c70eef81cab731b8bec9ee5686c9067e4718292469c63b5fe485a5cb
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Vi+A2BIsvGPxj4IxgIeMui0shvjYHzifmJ1ExLfYCOL8e5Y2QK2Lqr8aI9wzQRmsr2PBqv1TBW4KuAoGx2BpBA==
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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": 1,
  "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. The wall maps were also re-encoded from their sources at a lower quality: 0.3 to 1.7 levels on average in rendered stills, which I cannot see side by side. 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": 1,
  "publishedAt": "2026-11-05T22:01:52.493Z",
  "rule": "If an `<img>` poster and a WebGL texture show the same picture, make the poster's `sizes` pick the texture's file and load the texture from the poster's `currentSrc`, so the cache serves it.",
  "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": 1,
  "why": ""
}