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Co-Authored-By: 狸花猫/Claude-Qwen3.6-Plus 🐾
87 lines
2.5 KiB
JavaScript
87 lines
2.5 KiB
JavaScript
import { distance } from './util';
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var EPSILON = 0.0001;
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/**
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* 使用牛顿切割法求最近的点
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* @param {number[]} xArr 点的 x 数组
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* @param {number[]} yArr 点的 y 数组
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* @param {number} x 指定的点 x
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* @param {number} y 指定的点 y
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* @param {Function} tCallback 差值函数
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*/
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export function nearestPoint(xArr, yArr, x, y, tCallback, length) {
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var t;
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var d = Infinity;
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var v0 = [x, y];
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var segNum = 20;
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if (length && length > 200) {
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segNum = length / 10;
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}
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var increaseRate = 1 / segNum;
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var interval = increaseRate / 10;
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for (var i = 0; i <= segNum; i++) {
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var _t = i * increaseRate;
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var v1 = [tCallback.apply(null, xArr.concat([_t])), tCallback.apply(null, yArr.concat([_t]))];
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var d1 = distance(v0[0], v0[1], v1[0], v1[1]);
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if (d1 < d) {
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t = _t;
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d = d1;
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}
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}
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// 提前终止
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if (t === 0) {
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return {
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x: xArr[0],
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y: yArr[0],
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};
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}
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if (t === 1) {
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var count = xArr.length;
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return {
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x: xArr[count - 1],
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y: yArr[count - 1],
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};
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}
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d = Infinity;
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for (var i = 0; i < 32; i++) {
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if (interval < EPSILON) {
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break;
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}
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var prev = t - interval;
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var next = t + interval;
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var v1 = [tCallback.apply(null, xArr.concat([prev])), tCallback.apply(null, yArr.concat([prev]))];
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var d1 = distance(v0[0], v0[1], v1[0], v1[1]);
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if (prev >= 0 && d1 < d) {
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t = prev;
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d = d1;
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}
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else {
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var v2 = [tCallback.apply(null, xArr.concat([next])), tCallback.apply(null, yArr.concat([next]))];
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var d2 = distance(v0[0], v0[1], v2[0], v2[1]);
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if (next <= 1 && d2 < d) {
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t = next;
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d = d2;
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}
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else {
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interval *= 0.5;
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}
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}
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}
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return {
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x: tCallback.apply(null, xArr.concat([t])),
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y: tCallback.apply(null, yArr.concat([t])),
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};
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}
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// 近似求解 https://community.khronos.org/t/3d-cubic-bezier-segment-length/62363/2
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export function snapLength(xArr, yArr) {
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var totalLength = 0;
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var count = xArr.length;
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for (var i = 0; i < count; i++) {
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var x = xArr[i];
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var y = yArr[i];
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var nextX = xArr[(i + 1) % count];
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var nextY = yArr[(i + 1) % count];
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totalLength += distance(x, y, nextX, nextY);
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}
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return totalLength / 2;
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}
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//# sourceMappingURL=bezier.js.map
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