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https://github.com/luxfi/tel.git
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zeekayandHanzo Dev
78062c4a99
Globe.tsx was 23% comment. The code says what it does; the comments now say only what it cannot — why sidereal and not a phase, why one seam carries no cross-links, why a terminal tracks one satellite. Same for Nav, the tests, the workflow and LLM.md. Co-authored-by: Hanzo Dev <[email protected]>
92 lines
3.2 KiB
JavaScript
92 lines
3.2 KiB
JavaScript
/*
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Rasterises coastlines into `src/content/land.ts`.
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Run: node scripts/land.mjs path/to/countries.geojson
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Scanline by latitude row, even-odd fill — so lakes fall out without ring winding,
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and it is ~200x less work than point-in-polygon per cell.
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*/
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import { readFileSync, writeFileSync } from 'node:fs'
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const STEP = 1.5
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const COLS = Math.round(360 / STEP)
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const ROWS = Math.round(180 / STEP)
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const src = process.argv[2]
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if (!src) {
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console.error('usage: node scripts/land.mjs <countries.geojson>')
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process.exit(1)
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}
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/** Every ring of every feature, flattened — the fill rule does not care which is which. */
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const rings = []
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for (const f of JSON.parse(readFileSync(src, 'utf8')).features) {
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const g = f.geometry
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if (!g) continue
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if (g.type === 'Polygon') rings.push(...g.coordinates)
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else if (g.type === 'MultiPolygon') for (const poly of g.coordinates) rings.push(...poly)
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}
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const bits = new Uint8Array(Math.ceil((COLS * ROWS) / 8))
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const set = (col, row) => {
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const i = row * COLS + col
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bits[i >> 3] |= 1 << (i & 7)
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}
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for (let row = 0; row < ROWS; row++) {
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// Cell CENTRE, not its edge: a row sampled at its boundary sits exactly on the
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// coastline for any coast that runs east-west, and picks up a rounding coin flip.
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const lat = -90 + (row + 0.5) * STEP
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const xs = []
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for (const ring of rings) {
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for (let i = 0; i < ring.length - 1; i++) {
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const [lon1, lat1] = ring[i]
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const [lon2, lat2] = ring[i + 1]
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// Half-open in latitude so a vertex exactly on the row counts once, not twice.
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if (lat1 <= lat === lat2 <= lat) continue
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xs.push(lon1 + ((lat - lat1) / (lat2 - lat1)) * (lon2 - lon1))
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}
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}
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if (xs.length < 2) continue
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xs.sort((a, b) => a - b)
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for (let i = 0; i + 1 < xs.length; i += 2) {
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const from = Math.ceil((xs[i] + 180) / STEP - 0.5)
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const to = Math.floor((xs[i + 1] + 180) / STEP - 0.5)
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for (let col = Math.max(0, from); col <= Math.min(COLS - 1, to); col++) set(col, row)
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}
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}
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let land = 0
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for (const b of bits) land += b.toString(2).replace(/0/g, '').length
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writeFileSync(
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new URL('../src/content/land.ts', import.meta.url),
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`/*
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Where the land is — ${COLS}×${ROWS} cells of ${STEP}°, one bit each, row 0 at the
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south pole, column 0 at 180°W. ${land} land cells. Generated by scripts/land.mjs.
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A mask, not a list of dots: the renderer picks its own lattice and asks this.
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*/
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export const LAND_STEP = ${STEP}
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export const LAND_COLS = ${COLS}
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export const LAND_ROWS = ${ROWS}
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const PACKED =
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'${Buffer.from(bits).toString('base64')}'
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const bits_ = typeof atob === 'function'
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? Uint8Array.from(atob(PACKED), (c) => c.charCodeAt(0))
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: Uint8Array.from(Buffer.from(PACKED, 'base64'))
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/** True where (lat, lon) in degrees is over land. */
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export function isLand(lat: number, lon: number): boolean {
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const row = Math.floor((lat + 90) / LAND_STEP)
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const col = Math.floor(((((lon + 180) % 360) + 360) % 360) / LAND_STEP)
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if (row < 0 || row >= LAND_ROWS) return false
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const i = row * LAND_COLS + col
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return (bits_[i >> 3] & (1 << (i & 7))) !== 0
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}
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`,
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)
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console.log(`land.ts: ${COLS}x${ROWS} @ ${STEP}deg, ${land} land cells (${((land / (COLS * ROWS)) * 100).toFixed(1)}%), ${bits.length} bytes`)
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