@davepagurek/flo-mat/src/find-2-prong/find-and-add-hole-closing-2-prongs.ts

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

import { LlRbTree } from 'flo-ll-rb-tree';
import { Loop } from 'flo-boolean';
import { CpNode } from '../cp-node/cp-node.js';
import { getShapeBounds } from '../svg/get-shape-bounds.js';
import { getMinYPos } from '../svg/get-min-y-pos.js';
import { find2Prong } from './find-2-prong.js';
import { add2Prong } from './add-2-prong.js';


/**
 * @internal
 * Find and add two-prongs that remove any holes in the shape.
 * @param loops The loops (that as a precondition must be ordered from 
 * highest (i.e. smallest y-value) topmost point loops to lowest)
 * @param cpTrees
 * @param extreme The maximum coordinate value used to calculate floating point
 * tolerances.
 */
function findAndAddHoleClosing2Prongs(
        loops: Loop[],
        cpTrees: Map<Loop,LlRbTree<CpNode>>,
        extreme: number) {

    const bounds = getShapeBounds(loops);
    const squaredDiagonalLength = 
        (bounds.maxX.p[0] - bounds.minX.p[0])**2 +
        (bounds.maxY.p[1] - bounds.minY.p[1])**2;

    // Find the topmost points on each loop.
    const minYs = loops.map(getMinYPos);

    // We start at 1 since 0 is the outer (root) loop
    for (let k=1; k<minYs.length; k++) {
        const posSource = minYs[k];
        
        const holeClosingTwoProng = find2Prong(
            0, loops, extreme, squaredDiagonalLength, cpTrees, posSource, true, k, false
        );

        if (!holeClosingTwoProng) { 
            throw new Error(`Unable to find hole-closing 2-prong`);
        } 

        // TODO important - handle case of n-prong, i.e. more than one antipode
        // - currently we only handle case of single antipode (the general case)
        const { circle, zs: posAntipodes } = holeClosingTwoProng;

        add2Prong(cpTrees, circle, posSource, [posAntipodes[0]], true, extreme);
    }	
}


export { findAndAddHoleClosing2Prongs }