constructor( sceneA, cameraA, sceneB, cameraB ) {

		super();

		/**
		 * The first scene.
		 *
		 * @type {Scene}
		 */
		this.sceneA = sceneA;


		/**
		 * The camera of the first scene.
		 *
		 * @type {Camera}
		 */
		this.cameraA = cameraA;

		/**
		 * The second scene.
		 *
		 * @type {Scene}
		 */
		this.sceneB = sceneB;

		/**
		 * The camera of the second scene.
		 *
		 * @type {Camera}
		 */
		this.cameraB = cameraB;

		/**
		 * The pass material.
		 *
		 * @type {ShaderMaterial}
		 */
		this.material = this._createMaterial();

		// internals

		this._renderTargetA = new WebGLRenderTarget();
		this._renderTargetA.texture.type = HalfFloatType;
		this._renderTargetB = new WebGLRenderTarget();
		this._renderTargetB.texture.type = HalfFloatType;

		this._fsQuad = new FullScreenQuad( this.material );

	}
Constructs a render transition pass.

@param {Scene} sceneA - The first scene.
@param {Camera} cameraA - The camera of the first scene.
@param {Scene} sceneB - The second scene.
@param {Camera} cameraB - The camera of the second scene.