code: function getBarrelCurveConstants(width, height) {
    return {
      heightOffset: Math.min(15, 0.05 * height),
      widthOffset: Math.min(100, 0.25 * width),
      ctrlPtOffsetPct: 0.05
    };
  }
docs: get curve width, height, and control point position offsets as a percentage of node height / width