getMaterialData( material ) {

		const data = {};

		for ( const property of this.refreshUniforms ) {

			const value = material[ property ];

			if ( value === null || value === undefined ) continue;

			if ( typeof value === 'object' && value.clone !== undefined ) {

				if ( value.isTexture === true ) {

					data[ property ] = { id: value.id, version: value.version };

				} else {

					data[ property ] = value.clone();

				}

			} else {

				data[ property ] = value;

			}

		}

		return data;

	}
Returns a material data structure holding the material property values for
monitoring.

@param {Material} material - The material.
@return {Object} An object for monitoring material properties.