thi-ng/umbrella

import type { Maybe } from "@thi.ng/api";
import type { MultiFn2O } from "@thi.ng/defmulti";
import { defmulti } from "@thi.ng/defmulti/defmulti";
import type { IShape, PCLike, PathSegment } from "@thi.ng/geom-api";
import { closestPoint as closestPointArc } from "@thi.ng/geom-arc/closest-point";
import {
    closestPointAABB,
    closestPointRect,
} from "@thi.ng/geom-closest-point/box";
import { closestPointCircle } from "@thi.ng/geom-closest-point/circle";
import {
    closestPointPolyline,
    closestPointSegment,
} from "@thi.ng/geom-closest-point/line";
import { closestPointPlane } from "@thi.ng/geom-closest-point/plane";
import { closestPointArray } from "@thi.ng/geom-closest-point/points";
import { closestPointCubic } from "@thi.ng/geom-splines/cubic-closest-point";
import { closestPointQuadratic } from "@thi.ng/geom-splines/quadratic-closest-point";
import type { ReadonlyVec, Vec } from "@thi.ng/vectors";
import { add2, add3 } from "@thi.ng/vectors/add";
import { distSq2 } from "@thi.ng/vectors/distsq";
import { set2 } from "@thi.ng/vectors/set";
import type { AABB } from "./api/aabb.js";
import type { Arc } from "./api/arc.js";
import type { Circle } from "./api/circle.js";
import type { ComplexPolygon } from "./api/complex-polygon.js";
import type { Cubic } from "./api/cubic.js";
import type { Line } from "./api/line.js";
import type { Path } from "./api/path.js";
import type { Plane } from "./api/plane.js";
import type { Quadratic } from "./api/quadratic.js";
import type { Rect } from "./api/rect.js";
import { __dispatch } from "./internal/dispatch.js";

/**
 * Computes closest point to `p` on boundary of given shape. Writes result in
 * optionally provided output vector (or creates new one if omitted).
 *
 * @remarks
 * Currently implemented for:
 *
 * - {@link AABB}
 * - {@link Arc}
 * - {@link Circle}
 * - {@link ComplexPolygon}
 * - {@link Cubic}
 * - {@link Line}
 * - {@link Path}
 * - {@link Plane}
 * - {@link Points}
 * - {@link Points3}
 * - {@link Polygon}
 * - {@link Polyline}
 * - {@link Quad}
 * - {@link Quadratic}
 * - {@link Rect}
 * - {@link Sphere}
 *
 * @param shape
 * @param p
 * @param out
 */
export const closestPoint: MultiFn2O<
    IShape,
    ReadonlyVec,
    Vec,
    Maybe<Vec>
> = defmulti<any, ReadonlyVec, Maybe<Vec>, Maybe<Vec>>(
    __dispatch,
    {
        quad: "poly",
        points3: "points",
        sphere: "circle",
        tri: "poly",
    },
    {
        aabb: ($: AABB, p, out) =>
            closestPointAABB(p, $.pos, add3([], $.pos, $.size), out),

        arc: ($: Arc, p, out) =>
            closestPointArc(p, $.pos, $.r, $.axis, $.start, $.end, out),

        circle: ($: Circle, p, out) => closestPointCircle(p, $.pos, $.r, out),

        complexpoly: ($: ComplexPolygon, p, out) => {
            out = closestPointPolyline(p, $.boundary.points, true, out);
            let minD = distSq2(p, out!);
            let tmp: Vec = [];
            for (let child of $.children) {
                closestPointPolyline(p, child.points, true, tmp);
                const d = distSq2(p, tmp);
                if (d < minD) {
                    minD = d;
                    set2(out!, tmp);
                }
            }
            return out;
        },

        cubic: ({ points }: Cubic, p, out) =>
            closestPointCubic(
                p,
                points[0],
                points[1],
                points[2],
                points[3],
                out
            ),

        line: ({ points }: Line, p, out) =>
            closestPointSegment(p, points[0], points[1], out),

        path: ($: Path, p, out) => {
            let minD = Infinity;
            const $closestPSegment = (segments: PathSegment[]) => {
                for (let s of segments) {
                    if (!s.geo) continue;
                    const q = closestPoint(s.geo, p)!;
                    if (!q) continue;
                    const d = distSq2(p, q);
                    if (d < minD) {
                        minD = d;
                        out = set2(out || [], q);
                    }
                }
            };
            $closestPSegment($.segments);
            for (let sub of $.subPaths) $closestPSegment(sub);
            return out;
        },

        plane: ($: Plane, p, out) => closestPointPlane(p, $.normal, $.w, out),

        points: ($: PCLike, p, out) => closestPointArray(p, $.points, out),

        poly: ($: PCLike, p, out) =>
            closestPointPolyline(p, $.points, true, out),

        polyline: ($: PCLike, p, out) =>
            closestPointPolyline(p, $.points, false, out),

        quadratic: ({ points }: Quadratic, p, out) =>
            closestPointQuadratic(p, points[0], points[1], points[2], out),

        rect: ($: Rect, p, out) =>
            closestPointRect(p, $.pos, add2([], $.pos, $.size), out),
    }
);