setupDepth( builder ) {

		const { renderer, camera } = builder;

		// Depth

		let depthNode = this.depthNode;

		if ( depthNode === null ) {

			const mrt = renderer.getMRT();

			if ( mrt && mrt.has( 'depth' ) ) {

				depthNode = mrt.get( 'depth' );

			} else if ( renderer.logarithmicDepthBuffer === true ) {

				if ( camera.isPerspectiveCamera ) {

					depthNode = viewZToLogarithmicDepth( positionView.z, cameraNear, cameraFar );

				} else {

					depthNode = viewZToOrthographicDepth( positionView.z, cameraNear, cameraFar );

				}

			}

		}

		if ( depthNode !== null ) {

			depth.assign( depthNode ).toStack();

		}

	}
Setups the depth of this material.

@param {NodeBuilder} builder - The current node builder.