import Check from "./Check.js";
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import DeveloperError from "./DeveloperError.js";
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/**
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* Hilbert Order helper functions.
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*
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* @namespace HilbertOrder
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*/
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var HilbertOrder = {};
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/**
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* Computes the Hilbert index at the given level from 2D coordinates.
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*
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* @param {Number} level The level of the curve
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* @param {Number} x The X coordinate
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* @param {Number} y The Y coordinate
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* @returns {Number} The Hilbert index.
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* @private
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*/
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HilbertOrder.encode2D = function (level, x, y) {
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var n = Math.pow(2, level);
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//>>includeStart('debug', pragmas.debug);
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Check.typeOf.number("level", level);
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Check.typeOf.number("x", x);
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Check.typeOf.number("y", y);
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if (level < 1) {
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throw new DeveloperError("Hilbert level cannot be less than 1.");
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}
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if (x < 0 || x >= n || y < 0 || y >= n) {
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throw new DeveloperError("Invalid coordinates for given level.");
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}
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//>>includeEnd('debug');
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var p = {
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x: x,
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y: y,
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};
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var rx,
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ry,
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s,
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// eslint-disable-next-line no-undef
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index = BigInt(0);
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for (s = n / 2; s > 0; s /= 2) {
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rx = (p.x & s) > 0 ? 1 : 0;
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ry = (p.y & s) > 0 ? 1 : 0;
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// eslint-disable-next-line no-undef
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index += BigInt(((3 * rx) ^ ry) * s * s);
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rotate(n, p, rx, ry);
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}
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return index;
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};
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/**
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* Computes the 2D coordinates from the Hilbert index at the given level.
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*
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* @param {Number} level The level of the curve
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* @param {BigInt} index The Hilbert index
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* @returns {Number[]} An array containing the 2D coordinates ([x, y]) corresponding to the Morton index.
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* @private
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*/
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HilbertOrder.decode2D = function (level, index) {
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//>>includeStart('debug', pragmas.debug);
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Check.typeOf.number("level", level);
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Check.typeOf.bigint("index", index);
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if (level < 1) {
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throw new DeveloperError("Hilbert level cannot be less than 1.");
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}
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// eslint-disable-next-line no-undef
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if (index < BigInt(0) || index >= BigInt(Math.pow(4, level))) {
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throw new DeveloperError(
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"Hilbert index exceeds valid maximum for given level."
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);
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}
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//>>includeEnd('debug');
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var n = Math.pow(2, level);
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var p = {
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x: 0,
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y: 0,
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};
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var rx, ry, s, t;
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for (s = 1, t = index; s < n; s *= 2) {
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// eslint-disable-next-line no-undef
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rx = 1 & Number(t / BigInt(2));
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// eslint-disable-next-line no-undef
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ry = 1 & Number(t ^ BigInt(rx));
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rotate(s, p, rx, ry);
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p.x += s * rx;
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p.y += s * ry;
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// eslint-disable-next-line no-undef
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t /= BigInt(4);
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}
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return [p.x, p.y];
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};
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/**
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* @private
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*/
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function rotate(n, p, rx, ry) {
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if (ry !== 0) {
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return;
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}
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if (rx === 1) {
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p.x = n - 1 - p.x;
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p.y = n - 1 - p.y;
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}
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var t = p.x;
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p.x = p.y;
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p.y = t;
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}
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export default HilbertOrder;
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