@davepagurek/flo-mat/src/closest-boundary-point/closest-points-on-curve-precise.ts

Medial / Scale Axis Transform (MAT/SAT) Library.

import { ddDeflate, allRootsCertified, RootInterval } from 'flo-poly';
import { evalDeCasteljauDd, getFootpointPolyDd } from 'flo-bezier3';
import { Curve } from "../curve/curve.js";


/**
 * @internal
 * @param curve The curve
 * @param p The point from which to check
 * @param tRange The allowed t range
 * @param touchedCurve The bezier on which p is located
 * @param t The t value of the bezier that locates p
 */
function closestPointsOnCurvePrecise(
        curve: Curve, 
        p: number[], 
        [tS,tE]: number[] = [0,1], 
        touchedCurve: Curve,
        t: number): {
            p: number[];
            t: number;
        }[] {

    const _poly = getFootpointPolyDd(curve.ps, p);

    const poly = curve === touchedCurve
        ? ddDeflate(_poly, t)
        : _poly;

    const roots: Omit<RootInterval,'multiplicity'>[] = 
        allRootsCertified(poly, tS, tE);

    // Also test the endpoints
    const dontPush0 = (
        (t === 1 && curve === touchedCurve.next) ||
        (t === 0 && curve === touchedCurve)
    );

    const dontPush1 = (
        (t === 0 && curve === touchedCurve.prev) ||
        (t === 1 && curve === touchedCurve)
    );

    if (tS === 0) {
        if (!dontPush0) { roots.push({ tS: 0, tE: 0 }); }
    } else if (tS === 1) {
        if (!dontPush1) { roots.push({ tS: 1, tE: 1 }); }
    } else {
        roots.push({ tS: tS, tE: tS });
    }

    if (tE === 0) {
        if (!dontPush0) { roots.push({ tS: 0, tE: 0 }); }
    } else if (tE === 1) {
        if (!dontPush1) { roots.push({ tS: 1, tE: 1 }); }
    } else {
        roots.push({ tS: tE, tE: tE });
    }

    const ps = roots.map(
        root => { 
            const tS = root.tS;
            const tE = root.tE;
            const t = tS < 0 
                ? 0
                : tE > 1 ? 1 : (tS + tE)/2;
            return { p: evalDeCasteljauDd(curve.ps,[0,t]).map(v => v[1]), t }
        }
    );

    return ps;
}


export { closestPointsOnCurvePrecise }