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cleanup
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@missinglink
missinglink committed Aug 28, 2024
1 parent a95107d commit 3986873
Showing 1 changed file with 52 additions and 63 deletions.
115 changes: 52 additions & 63 deletions src/App.tsx
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Original file line number Diff line number Diff line change
Expand Up @@ -21,32 +21,31 @@ import {
MultiLineString,
} from "geojson";

const initialUnion = (): s2.CellUnion => {
const union = new s2.CellUnion();
const initialUnion = (): s2.CellUnion | void => {
// const union = new s2.CellUnion();
// union.push(s2.cellid.fromFace(0));
// union.push(s2.cellid.fromFace(1));
// union.push(s2.cellid.fromFace(2));
// union.push(s2.cellid.fromFace(3));
// union.push(s2.cellid.fromFace(4));
// union.push(s2.cellid.fromFace(5));

// union.push(2985886552946638848n);
// union.push(3008404551083491328n);
// union.push(3098476543630901248n);
// union.push(7710162562058289152n);
// union.push(7854277750134145024n);
// union.push(8286623314361712640n);
// union.push(11957057010668666880n);
// union.push(11979575008805519360n);
// union.push(12087661399862411264n);
// union.push(12393906174523604992n);
// union.push(5719853001737240576n);
// union.push(5476377146882523136n);
// union.push(4899916394579099648n);
// union.push(s2.cellid.fromToken("5b"));
// union.push(s2.cellid.fromToken("a4"));
// union.push(s2.cellid.fromToken("4c"));
return union;
// // union.push(2985886552946638848n);
// // union.push(3008404551083491328n);
// // union.push(3098476543630901248n);
// // union.push(7710162562058289152n);
// // union.push(7854277750134145024n);
// // union.push(8286623314361712640n);
// // union.push(11957057010668666880n);
// // union.push(11979575008805519360n);
// // union.push(12087661399862411264n);
// // union.push(12393906174523604992n);
// // union.push(5719853001737240576n);
// // union.push(5476377146882523136n);
// // union.push(4899916394579099648n);
// // union.push(s2.cellid.fromToken("5b"));
// // union.push(s2.cellid.fromToken("a4"));
// // union.push(s2.cellid.fromToken("4c"));
// return union;
};

const polygonBuilder = (polygon: Polygon): s2.Polygon => {
Expand Down Expand Up @@ -85,7 +84,11 @@ const getCovering = (
);
};

const wrapAntimeridianCrossings = (arcLines: FeatureCollection<LineString>) => {
// We adjust the lines from great-circle to have lng > 180 and < -180 so that
// the polygons render correctly.
const overflowAntimeridianCrossings = (
arcLines: FeatureCollection<LineString>,
) => {
if (arcLines.features.length <= 4) return;

const antimeridianCrossings: boolean[] = [];
Expand Down Expand Up @@ -113,7 +116,16 @@ const wrapAntimeridianCrossings = (arcLines: FeatureCollection<LineString>) => {
});
};

const fixPolarFaces = (arcs: Feature<LineString | MultiLineString>[]) => {
// The 'top' and 'bottom' faces are special-cased since all all points have equal lat.
// we add in an additional line segment so the top and bottom of the planar map are covered
// by the polygon.
const fixPolarFaces = (
cellid: bigint,
arcs: Feature<LineString | MultiLineString>[],
) => {
const POLAR_FACES = [s2.cellid.fromFace(2), s2.cellid.fromFace(5)];
if (!POLAR_FACES.includes(cellid)) return;

arcs.forEach((arc: Feature<LineString | MultiLineString>) => {
if (arc.geometry.type === "MultiLineString") {
const A = arc.geometry.coordinates[0].at(-1)!;
Expand All @@ -137,12 +149,15 @@ const fixPolarFaces = (arcs: Feature<LineString | MultiLineString>[]) => {
});
};

// When drawing to a pole the lng is not relevant, we borrow it from the previous point
// to avoid line drawing issues.
const fixPoles = (points: number[][]) => {
points.forEach((p, i) => {
if (Math.abs(p[1]) === 90) p[0] = points.at(i - 1)![0];
});
};

//The great-circle lib can sometimes use -180 lng instead of +180 and vice-versa
const fixFalseAntimeridianCrossings = (points: number[][]) => {
const exterior = points.filter((p) => Math.abs(p[0]) === 180);
if (exterior.length !== 2) return;
Expand All @@ -155,6 +170,19 @@ const fixFalseAntimeridianCrossings = (points: number[][]) => {
exterior.forEach((p) => (p[0] = Math.sign(interior[0][0]) * 180));
};

// The great-circle lib can generate a linestring with two identical points, remove them.
const removeRedundantArcs = (arcs: Feature<LineString | MultiLineString>[]) => {
arcs.forEach((arc: Feature<LineString | MultiLineString>) => {
if (arc.geometry.type !== "MultiLineString") return;
if (arc.geometry.coordinates.length !== 2) return;
arc.geometry.coordinates = arc.geometry.coordinates.filter((ls) => {
if (ls.length !== 2) return true;
if (ls[0][0] === ls[1][0] && ls[0][1] === ls[1][1]) return false;
return true;
});
});
};

const getCellVisualization = (union: s2.CellUnion): FeatureCollection => {
const degrees = s1.angle.degrees;
let features = [...union].map((cellid): Feature<Polygon> => {
Expand All @@ -172,51 +200,15 @@ const getCellVisualization = (union: s2.CellUnion): FeatureCollection => {
fixPoles([p0, p1, p2, p3]);
fixFalseAntimeridianCrossings([p0, p1, p2, p3]);

// console.log(p0, p1, p2, p3);

// if ([p0, p1, p2, p3].filter((p) => !p[0]).length % 2 !== 0) {
// console.log("potential line drawing issue", cellid);
// console.log(p0, p1, p2, p3);
// }

// if (
// [p0, p1, p2, p3].filter(
// (p) => Math.abs(p[0]) === 180 && Math.abs(p[1]) === 90,
// ).length
// ) {
// console.log("potential pole issue", cellid);
// console.log(p0, p1, p2, p3);
// }

const level = cell.level;
const npoints = 20 + (30 - level) * 3;
const arc0 = greatCircle(p0, p1, { npoints });
const arc1 = greatCircle(p1, p2, { npoints });
const arc2 = greatCircle(p2, p3, { npoints });
const arc3 = greatCircle(p3, p0, { npoints });

const removeRedundantArcs = (
arcs: Feature<LineString | MultiLineString>[],
) => {
arcs.forEach((arc: Feature<LineString | MultiLineString>) => {
if (arc.geometry.type !== "MultiLineString") return;
if (arc.geometry.coordinates.length !== 2) return;
arc.geometry.coordinates = arc.geometry.coordinates.filter((ls) => {
if (ls.length !== 2) return true;
if (ls[0][0] === ls[1][0] && ls[0][1] === ls[1][1]) return false;
return true;
});
});
};

removeRedundantArcs([arc0, arc1, arc2, arc3]);

// console.log(arc0, arc1, arc2, arc3);
// planar hacks for the two polar faces
const POLAR_FACES = [s2.cellid.fromFace(2), s2.cellid.fromFace(5)];
if (POLAR_FACES.includes(cellid)) {
fixPolarFaces([arc0, arc1, arc2, arc3]);
}
fixPolarFaces(cellid, [arc0, arc1, arc2, arc3]);

const arcLines: FeatureCollection<LineString> = {
type: "FeatureCollection",
Expand All @@ -228,10 +220,7 @@ const getCellVisualization = (union: s2.CellUnion): FeatureCollection => {
],
};

// fixes;
if (!POLAR_FACES.includes(cellid)) {
wrapAntimeridianCrossings(arcLines);
}
overflowAntimeridianCrossings(arcLines);

const coordinates = arcLines.features
.map((f) => f.geometry.coordinates)
Expand Down

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