@thi.ng/geom-tessellate/earcut-complex.d.ts

2D/3D convex polygon tessellators

import type { ReadonlyVec } from "@thi.ng/vectors";
import type { Tessellator } from "./api.js";
/**
 * Higher-order tessellator, implementing an ear slicing triangulation
 * algorithm, optionally optimized by Morton/Z-curve hashing/sorting and able to
 * handle complex polygons with holes, twists, degeneracies and
 * self-intersections.
 *
 * @remarks
 * This is an adapted version of https://github.com/mapbox/earcut with the
 * following changes to the original implementation:
 *
 * - Input points given as array of points (not flattened, only 2D supported)
 * - Appends results to given tessellation instance as per contract of all
 *   tessellators in this package
 * - Configurable Z-curve hashing threshold (default: 80)
 * - If Z-curve hashing is used, points are pre-scaled once internally for
 *   various simplifications and to avoid passing extraneous args around
 * - Use unsigned 16 bits (per coord) hashing (instead of 15 bits)
 * - Re-use existing thi.ng/umbrella fns for some processing steps
 * - Add small tolerance for colinear check
 * - Rename `Node` => `Vertex`
 * - Minor other refactoring (use of destructuring, add types, renames etc.)
 *
 * Original implementation Copyright (c) 2016, Mapbox, ISC License. Original
 * author: Volodymyr Agafonkin
 *
 * References:
 *
 * - https://www.cosy.sbg.ac.at/~held/projects/triang/triang.html
 * - https://www.geometrictools.com/Documentation/TriangulationByEarClipping.pdf
 * - https://docs.thi.ng/umbrella/morton/
 *
 * @param holeIDs
 * @param hashThreshold
 */
export declare const earCutComplex: (holeIDs?: number[], hashThreshold?: number) => Tessellator;
/**
 * Takes an array of `boundary` points and another array of `holes` containing
 * point arrays of individual holes. Concatenates all points (both boundary &
 * holes) and returns a tuple of `[points, holeIDs]`, suitable for
 * {@link earCutComplex}.
 *
 * @example
 * ```ts tangle:../export/earcut-complex.ts
 * import {
 *   earCutComplex, earCutComplexPrepare, tessellate
 * } from "@thi.ng/geom-tessellate";
 *
 * const boundary = [[0,0], [100,0], [100,100], [0,100]];
 * const hole = [[20,20],[50,80],[80,20]];
 *
 * const [points, holeIDs] = earCutComplexPrepare(boundary, [hole]);
 *
 * const tess = tessellate(points, earCutComplex(holeIDs));
 *
 * console.log(tess);
 * // {
 * //   points: [
 * //     [ 0, 0 ], [ 100, 0 ], [ 100, 100 ], [ 0, 100 ],
 * //     [ 20, 20 ], [ 50, 80 ], [ 80, 20 ]
 * //   ],
 * //   indices: [
 * //     [ 0, 4, 5 ], [ 6, 4, 0 ], [ 3, 0, 5 ], [ 6, 0, 1 ],
 * //     [ 2, 3, 5 ], [ 5, 6, 1 ], [ 1, 2, 5 ]
 * //   ],
 * // }
 * ```
 *
 * @param boundary
 * @param holes
 */
export declare const earCutComplexPrepare: (boundary: ReadonlyVec[], holes: ReadonlyVec[][]) => [ReadonlyVec[], number[]];
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