import { useI18n } from '@/lib/i18n';
// The sky, seen from underneath it.
//
// The map answers "where is the satellite over the earth". This answers "where
// do I look", which during a pass is the question that matters: whether the
// bird comes over the top or clips the horizon behind the house is something no
// amount of azimuth and elevation digits conveys, and one glance at a polar
// plot settles it.
//
// The projection is the one every satellite tracker uses and every operator
// already reads: the centre is the zenith, the outer circle is the horizon, and
// north is up. So the radius is (90 − elevation), NOT the elevation — a
// satellite overhead is a dot in the middle, and a pass that stays near the rim
// is one that never rises.
export type SkyPoint = { at: string; az: number; el: number };
export function SkyPlot({ track, az, el, name, visible, size = 300 }: {
// The pass, sampled from rise to set. Empty draws the dial alone, which is
// still worth showing: it says where the antenna is pointing now.
track: SkyPoint[];
// Where the satellite is at this instant, or null when it is not up.
az?: number | null;
el?: number | null;
name?: string;
visible?: boolean;
size?: number;
}) {
const { t } = useI18n();
const R = size / 2 - 14; // the horizon circle
const cx = size / 2, cy = size / 2;
// Where a bearing and an elevation land on the dial.
const pt = (azDeg: number, elDeg: number): [number, number] => {
const r = R * (90 - Math.max(0, Math.min(90, elDeg))) / 90;
const a = (azDeg * Math.PI) / 180;
return [cx + r * Math.sin(a), cy - r * Math.cos(a)];
};
const rings = [15, 30, 45, 60, 75];
const path = track.length > 1
? track.map((p, i) => `${i === 0 ? 'M' : 'L'}${pt(p.az, p.el).map((v) => v.toFixed(1)).join(' ')}`).join(' ')
: '';
// Ticks every 10°, longer every 30°, so the rim reads as a compass rather
// than a plain circle.
const ticks = [];
for (let a = 0; a < 360; a += 10) {
const long = a % 30 === 0;
const rad = (a * Math.PI) / 180;
const r1 = R, r2 = R - (long ? 7 : 4);
ticks.push(
,
);
}
const here = az != null && el != null ? pt(az, el) : null;
const start = track.length > 1 ? pt(track[0].az, track[0].el) : null;
const end = track.length > 1 ? pt(track[track.length - 1].az, track[track.length - 1].el) : null;
return (
);
}