mirror of
https://github.com/bilawalsidhu/gods-eye-view.git
synced 2026-11-04 18:34:02 +00:00
Gustavo Beneduzi
deb34ebe35
Add a Wind layer animating the global 10 m wind field from NOAA GFS. The /api/wind proxy selects the latest available 0.25° cycle, reads its .idx inventory, byte-range fetches only the UGRD/VGRD 10 m GRIB2 messages (~1 MB each instead of the whole ~500 MB file), decodes them with ecCodes (WASM), resamples to a compact grid (1° default), and serves a manifest plus a Float32 U/V payload cached per cycle for an hour (single-flight, last-good on failure). The client renders nullschool-style particles in a canvas overlay: bilinear field sampling with longitude wrap, per-frame advection, Cesium camera projection, and globe-occlusion culling via EllipsoidalOccluder. Validated end-to-end against the real 2026-09-14 06z cycle on Node 25 (180x91 grid at 2°, 131,040-byte payload, plausible mean |u|/|v|). The WASM decoder requires Node >=24, which the repo already requires. Registered as `wind` (token k) with attribution and docs. Verified: npm test (3412 pass, 0 fail), npm run check:boundaries.
64 lines
2.2 KiB
JavaScript
64 lines
2.2 KiB
JavaScript
import os from 'node:os';
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import path from 'node:path';
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import { promises as fs } from 'node:fs';
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import { randomUUID } from 'node:crypto';
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/**
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* Lazily created ecCodes WASM instance. The `@meri-imperiumi/eccodes-wasm`
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* module is only imported on first use so unit tests can inject a fake
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* decoder without loading the WASM (which requires Node >= 24).
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* @type {?Promise<object>}
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*/
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let eccodesPromise = null;
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/** @returns {Promise<object>} The shared ecCodes WASM instance. */
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function loadEccodes() {
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eccodesPromise ??= (async () => {
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const module = await import('@meri-imperiumi/eccodes-wasm');
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return module.createEccodes();
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})();
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return eccodesPromise;
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}
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/**
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* Decode one GRIB2 wind message into its grid metadata and values.
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*
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* The WASM decoder reads from its own mounted filesystem, so the message is
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* written to a temp file under `mountDir` and removed in `finally`.
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*
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* @param {Buffer} buffer - One GRIB2 message (already byte-range extracted).
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* @param {{ eccodesModule?: object, mountDir?: string }} [options]
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* @returns {Promise<{ni: number, nj: number, lo1: number, la1: number,
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* di: number, dj: number, values: ArrayLike<number>, shortName: string,
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* level: number, units: string}>}
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*/
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export async function decodeWindGribMessage(
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buffer,
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{ eccodesModule, mountDir = os.tmpdir() } = {},
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) {
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const eccodes = eccodesModule ?? (await loadEccodes());
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const name = `wind-${randomUUID()}.grib2`;
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const file = path.join(mountDir, name);
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await fs.writeFile(file, buffer);
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let handle = null;
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try {
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eccodes.mountFilesystem(mountDir);
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handle = eccodes.openGrib(file);
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return {
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ni: handle.getLong('Ni'),
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nj: handle.getLong('Nj'),
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lo1: handle.getDouble('longitudeOfFirstGridPointInDegrees'),
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la1: handle.getDouble('latitudeOfFirstGridPointInDegrees'),
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di: handle.getDouble('iDirectionIncrementInDegrees'),
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dj: handle.getDouble('jDirectionIncrementInDegrees'),
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values: handle.getDoubleArray('values'),
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shortName: handle.getString('shortName'),
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level: handle.getLong('level'),
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units: handle.getString('units'),
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};
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} finally {
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if (handle) handle.delete();
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await fs.unlink(file).catch(() => {});
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}
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}
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