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| /**
| * 贝塞尔平滑曲线
| */
|
| import {
| min as v2Min,
| max as v2Max,
| scale as v2Scale,
| distance as v2Distance,
| add as v2Add,
| clone as v2Clone,
| sub as v2Sub,
| VectorArray
| } from '../../core/vector';
|
| /**
| * 贝塞尔平滑曲线
| * @param points 线段顶点数组
| * @param smooth 平滑等级, 0-1
| * @param isLoop
| * @param constraint 将计算出来的控制点约束在一个包围盒内
| * 比如 [[0, 0], [100, 100]], 这个包围盒会与
| * 整个折线的包围盒做一个并集用来约束控制点。
| * @param 计算出来的控制点数组
| */
| export default function smoothBezier(
| points: VectorArray[],
| smooth?: number,
| isLoop?: boolean,
| constraint?: VectorArray[]
| ) {
| const cps = [];
|
| const v: VectorArray = [];
| const v1: VectorArray = [];
| const v2: VectorArray = [];
| let prevPoint;
| let nextPoint;
|
| let min;
| let max;
| if (constraint) {
| min = [Infinity, Infinity];
| max = [-Infinity, -Infinity];
| for (let i = 0, len = points.length; i < len; i++) {
| v2Min(min, min, points[i]);
| v2Max(max, max, points[i]);
| }
| // 与指定的包围盒做并集
| v2Min(min, min, constraint[0]);
| v2Max(max, max, constraint[1]);
| }
|
| for (let i = 0, len = points.length; i < len; i++) {
| const point = points[i];
|
| if (isLoop) {
| prevPoint = points[i ? i - 1 : len - 1];
| nextPoint = points[(i + 1) % len];
| }
| else {
| if (i === 0 || i === len - 1) {
| cps.push(v2Clone(points[i]));
| continue;
| }
| else {
| prevPoint = points[i - 1];
| nextPoint = points[i + 1];
| }
| }
|
| v2Sub(v, nextPoint, prevPoint);
|
| // use degree to scale the handle length
| v2Scale(v, v, smooth);
|
| let d0 = v2Distance(point, prevPoint);
| let d1 = v2Distance(point, nextPoint);
| const sum = d0 + d1;
| if (sum !== 0) {
| d0 /= sum;
| d1 /= sum;
| }
|
| v2Scale(v1, v, -d0);
| v2Scale(v2, v, d1);
| const cp0 = v2Add([], point, v1);
| const cp1 = v2Add([], point, v2);
| if (constraint) {
| v2Max(cp0, cp0, min);
| v2Min(cp0, cp0, max);
| v2Max(cp1, cp1, min);
| v2Min(cp1, cp1, max);
| }
| cps.push(cp0);
| cps.push(cp1);
| }
|
| if (isLoop) {
| cps.push(cps.shift());
| }
|
| return cps;
| }
|
|
