@davepagurek/flo-mat/src/find-2-prong/get-initial-bezier-pieces.ts

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

import { LlRbTree } from 'flo-ll-rb-tree';
import { Loop } from 'flo-boolean';
import { getNeighbouringPoints } from '../mat/get-neighboring-cps.js';
import { getBoundaryPieceBeziers } from '../mat/get-boundary-piece-beziers.js';
import { BezierPiece  } from '../mat/bezier-piece.js';
import { CpNode } from '../cp-node/cp-node.js';
import { PointOnShape } from '../point-on-shape/point-on-shape.js';
import { isPosDullCorner } from '../point-on-shape/is-pos-dull-corner.js';
import { calcPosOrder } from '../point-on-shape/calc-pos-order.js';
import { Circle } from '../geometry/circle.js';


/** @internal */
function getInitialBezierPieces(
        angle: number,
        isHoleClosing: boolean,
        k: number,
        loops: Loop[],
        cpTrees: Map<Loop,LlRbTree<CpNode>>,
        y: PointOnShape,
        circle: Circle) {

    if (isHoleClosing) {
        const bezierPieces: BezierPiece[] = [];
        for (let k2=0; k2<k; k2++) {
            const pieces: BezierPiece[] = loops[k2].curves
                .map(curve => ({ curve, ts: [0,1] }))
            bezierPieces.push(...pieces);
        }

        return { bezierPieces, δ: undefined };
    }

    let bezierPieces: BezierPiece[];
    const order = isPosDullCorner(y)
            ? y.t === 1 && angle === 0
                ? -1 
                : y.t === 0
                ? +1
                : calcPosOrder(circle, y)
            : 0;

    const loop = loops[k];
    const cpNode = getNeighbouringPoints(cpTrees.get(loop)!, y, order, 0)[0];
    const δ = [cpNode, cpNode];
    if (!cpNode || 
        // The special case if there is only a single sharp corner or 
        // terminating 2-prong currently in the MAT. Don't remove!
        (cpNode === cpNode.next.next) 
    ) {
        bezierPieces = loop.curves
            .map(curve => ({ curve, ts: [0,1] }))
    } else {
        bezierPieces = getBoundaryPieceBeziers(δ);	
    }

    return { bezierPieces, δ };
}


export { getInitialBezierPieces }