copy( source ) {

		super.copy( source );

		this.map = source.map;

		this.alphaMap = source.alphaMap;

		this.displacementMap = source.displacementMap;
		this.displacementScale = source.displacementScale;
		this.displacementBias = source.displacementBias;

		return this;

	}
The offset of the displacement map's values on the mesh's vertices.
The bias is added to the scaled sample of the displacement map.
Without a displacement map set, this value is not applied.

@type {number}
@default 0