| /** |
| * Catmull-Rom spline 插值折线 |
| * @module zrender/shape/util/smoothSpline |
| * @author pissang (https://www.github.com/pissang) |
| * Kener (@Kener-林峰, kener.linfeng@gmail.com) |
| * errorrik (errorrik@gmail.com) |
| */ |
| import { distance as v2Distance } from '../../core/vector'; |
| /** |
| * @inner |
| */ |
| |
| function interpolate(p0, p1, p2, p3, t, t2, t3) { |
| var v0 = (p2 - p0) * 0.5; |
| var v1 = (p3 - p1) * 0.5; |
| return (2 * (p1 - p2) + v0 + v1) * t3 + (-3 * (p1 - p2) - 2 * v0 - v1) * t2 + v0 * t + p1; |
| } |
| /** |
| * @alias module:zrender/shape/util/smoothSpline |
| * @param {Array} points 线段顶点数组 |
| * @param {boolean} isLoop |
| * @return {Array} |
| */ |
| |
| |
| export default function (points, isLoop) { |
| var len = points.length; |
| var ret = []; |
| var distance = 0; |
| |
| for (var i = 1; i < len; i++) { |
| distance += v2Distance(points[i - 1], points[i]); |
| } |
| |
| var segs = distance / 2; |
| segs = segs < len ? len : segs; |
| |
| for (var i = 0; i < segs; i++) { |
| var pos = i / (segs - 1) * (isLoop ? len : len - 1); |
| var idx = Math.floor(pos); |
| var w = pos - idx; |
| var p0; |
| var p1 = points[idx % len]; |
| var p2; |
| var p3; |
| |
| if (!isLoop) { |
| p0 = points[idx === 0 ? idx : idx - 1]; |
| p2 = points[idx > len - 2 ? len - 1 : idx + 1]; |
| p3 = points[idx > len - 3 ? len - 1 : idx + 2]; |
| } else { |
| p0 = points[(idx - 1 + len) % len]; |
| p2 = points[(idx + 1) % len]; |
| p3 = points[(idx + 2) % len]; |
| } |
| |
| var w2 = w * w; |
| var w3 = w * w2; |
| ret.push([interpolate(p0[0], p1[0], p2[0], p3[0], w, w2, w3), interpolate(p0[1], p1[1], p2[1], p3[1], w, w2, w3)]); |
| } |
| |
| return ret; |
| } |