resume() {
    if (this._active) {
      if (this._isPaused) {
        this._isPaused = false;
        let i, l;
        if (this.scopes) {
          for (i = 0, l = this.scopes.length; i < l; i++) {
            this.scopes[i].resume();
          }
        }
        for (i = 0, l = this.effects.length; i < l; i++) {
          this.effects[i].resume();
        }
      }
    }
  }
Resumes the effect scope, including all child scopes and effects.