123 lines
3.9 KiB
JavaScript
123 lines
3.9 KiB
JavaScript
// Shared helpers used across layers. Cesium and satellite are CDN globals.
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const Cesium = window.Cesium;
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// Build an offscreen canvas glyph for a BillboardCollection.
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export function makeGlyphCanvas(size, drawFn) {
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const c = document.createElement('canvas');
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c.width = size;
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c.height = size;
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drawFn(c.getContext('2d'), size);
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return c;
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}
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// White upward-pointing triangle (aircraft). Tinted per-billboard via .color.
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export function aircraftGlyph() {
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return makeGlyphCanvas(32, (g) => {
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g.fillStyle = '#ffffff';
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g.beginPath();
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g.moveTo(16, 2);
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g.lineTo(28, 30);
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g.lineTo(16, 23);
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g.lineTo(4, 30);
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g.closePath();
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g.fill();
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});
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}
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// Upward teardrop/flame (wildfires). Drawn directly in `hex` with a dark
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// outline — one shared canvas reused across every fire billboard.
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export function flameGlyph(hex) {
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return makeGlyphCanvas(28, (g, s) => {
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const cx = s / 2;
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g.beginPath();
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g.moveTo(cx, 3); // pointed top
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g.bezierCurveTo(s * 0.86, s * 0.34, s * 0.80, s * 0.72, cx, s - 4);
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g.bezierCurveTo(s * 0.20, s * 0.72, s * 0.14, s * 0.34, cx, 3);
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g.closePath();
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g.fillStyle = hex;
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g.fill();
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g.lineWidth = 2;
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g.strokeStyle = '#0a0f14';
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g.stroke();
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});
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}
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// White diamond (ships).
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export function shipGlyph() {
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return makeGlyphCanvas(28, (g) => {
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g.fillStyle = '#ffffff';
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g.beginPath();
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g.moveTo(14, 2);
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g.lineTo(26, 14);
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g.lineTo(14, 26);
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g.lineTo(2, 14);
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g.closePath();
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g.fill();
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});
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}
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// Great-circle initial bearing, degrees (0 = north, clockwise).
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export function bearingDeg(lat1, lon1, lat2, lon2) {
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const toR = Math.PI / 180;
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const p1 = lat1 * toR;
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const p2 = lat2 * toR;
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const dl = (lon2 - lon1) * toR;
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const y = Math.sin(dl) * Math.cos(p2);
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const x = Math.cos(p1) * Math.sin(p2) - Math.sin(p1) * Math.cos(p2) * Math.cos(dl);
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return (Math.atan2(y, x) * 180 / Math.PI + 360) % 360;
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}
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// Aircraft altitude → band color.
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export function altitudeColor(CONFIG, altMeters) {
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const c = CONFIG.colors;
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if (altMeters == null) return c.aircraftHigh;
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if (altMeters < 3000) return c.aircraftLow;
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if (altMeters < 9000) return c.aircraftMid;
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return c.aircraftHigh;
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}
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// Escape a string for safe interpolation into InfoBox description HTML.
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// Feeds like USGS/EONET are trusted, but this is defense-in-depth for the
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// public deploy (and the InfoBox is a real HTML sink).
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export function escapeHtml(s) {
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return String(s == null ? '' : s)
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.replace(/&/g, '&')
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.replace(/</g, '<')
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.replace(/>/g, '>')
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.replace(/"/g, '"')
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.replace(/'/g, ''');
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}
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// Only allow http(s) URLs into href attributes (blocks javascript:/data: URLs).
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export function safeUrl(u) {
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const s = String(u == null ? '' : u).trim();
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return /^https?:\/\//i.test(s) ? s : '';
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}
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// CSS hex → Cesium.Color, optional alpha.
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export function cz(hex, alpha) {
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const col = Cesium.Color.fromCssColorString(hex);
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return alpha == null ? col : col.withAlpha(alpha);
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}
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// Billboard screen-space rotation (CCW) for a compass heading (CW from north).
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export function headingToRotation(headingDeg) {
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return -Cesium.Math.toRadians(headingDeg || 0);
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}
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// Dead-reckon a fix forward along its course: equirectangular advance, good to
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// well under a pixel for the few minutes between ADS-B polls (mirrors the
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// open-sourced God's Eye View "smooth motion from choppy data" idea).
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// ponytail: flat-earth step, swap for geodesic if we ever extrapolate >10 min.
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const EARTH_R = 6371000;
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export function deadReckon(lon, lat, velMps, trackDeg, dtSec) {
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const d = (velMps || 0) * dtSec;
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if (!d || !isFinite(d)) return { lon, lat };
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const th = (trackDeg || 0) * Math.PI / 180;
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const latR = lat * Math.PI / 180;
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const newLat = lat + (d * Math.cos(th) / EARTH_R) * 180 / Math.PI;
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const newLon = lon + (d * Math.sin(th) / (EARTH_R * Math.max(0.05, Math.cos(latR)))) * 180 / Math.PI;
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return { lon: ((newLon + 540) % 360) - 180, lat: Math.max(-89.9, Math.min(89.9, newLat)) };
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}
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