linearShadowDistance = ( light ) => {

	const camera = light.shadow.camera;

	const nearDistance = reference( 'near', 'float', camera ).setGroup( renderGroup );
	const farDistance = reference( 'far', 'float', camera ).setGroup( renderGroup );

	const referencePosition = objectPosition( light );

	return linearDistance( referencePosition, nearDistance, farDistance );

}
A shadow filtering function performing VSM filtering.

@method
@param {Object} inputs - The input parameter object.
@param {DepthTexture} inputs.depthTexture - A reference to the shadow map's texture data.
@param {Node<vec3>} inputs.shadowCoord - The shadow coordinates.
@return {Node<float>} The filtering result.