build/postprocessing.esm.js
function smoothArea(d, b) {

	const a1 = b.min;
	const a2 = b.max;

	const b1X = Math.sqrt(a1.x * 2.0) * 0.5;
	const b1Y = Math.sqrt(a1.y * 2.0) * 0.5;
	const b2X = Math.sqrt(a2.x * 2.0) * 0.5;
	const b2Y = Math.sqrt(a2.y * 2.0) * 0.5;

	const p = saturate(d / SMOOTH_MAX_DISTANCE);

	a1.set(lerp(b1X, a1.x, p), lerp(b1Y, a1.y, p));
	a2.set(lerp(b2X, a2.x, p), lerp(b2Y, a2.y, p));

	return b;

}
function smoothArea(d, b) {

	const a1 = b.min;
	const a2 = b.max;

	const b1X = Math.sqrt(a1.x * 2.0) * 0.5;
	const b1Y = Math.sqrt(a1.y * 2.0) * 0.5;
	const b2X = Math.sqrt(a2.x * 2.0) * 0.5;
	const b2Y = Math.sqrt(a2.y * 2.0) * 0.5;

	const p = saturate(d / SMOOTH_MAX_DISTANCE);

	a1.set(lerp(b1X, a1.x, p), lerp(b1Y, a1.y, p));
	a2.set(lerp(b2X, a2.x, p), lerp(b2Y, a2.y, p));

	return b;

}
A smoothing function for small U-patterns.

@private
@param {Number} d - A smoothing factor.
@param {Box2} b - The area that should be smoothed.
@return {Box2} The smoothed area.