How to use the @antv/matrix-util.vec2.sub function in @antv/matrix-util

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(point);
        continue;
      } else {
        prevPoint = points[i - 1];
        nextPoint = points[i + 1];
      }
    }
    let v = [];
    v = vec2.sub(v, nextPoint, prevPoint);
    v = vec2.scale(v, v, smooth);

    let d0 = vec2.distance(point, prevPoint);
    let d1 = vec2.distance(point, nextPoint);

    const sum = d0 + d1;
    if (sum !== 0) {
      d0 /= sum;
      d1 /= sum;
    }

    const v1 = vec2.scale([], v, -d0);
    const v2 = vec2.scale([], v, d1);

    let cp0 = vec2.add([], point, v1);
    let cp1 = vec2.add([], point, v2);

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(point);
        continue;
      } else {
        prevPoint = points[i - 1];
        nextPoint = points[i + 1];
      }
    }
    let v = [];
    v = vector2.sub(v, nextPoint, prevPoint);
    v = vector2.scale(v, v, smooth);

    let d0 = vector2.distance(point, prevPoint);
    let d1 = vector2.distance(point, nextPoint);

    const sum = d0 + d1;
    if (sum !== 0) {
      d0 /= sum;
      d1 /= sum;
    }

    const v1 = vector2.scale([], v, -d0);
    const v2 = vector2.scale([], v, d1);

    let cp0 = vector2.add([], point, v1);
    let cp1 = vector2.add([], point, v2);