copy( source ) {

		super.copy( source );

		this._hasExternalTextures = source._hasExternalTextures;
		this._autoAllocateDepthBuffer = source._autoAllocateDepthBuffer;
		this._isOpaqueFramebuffer = source._isOpaqueFramebuffer;

		return this;

	}
Whether this render target is associated with a XRWebGLLayer.

A XRWebGLLayer points to an opaque framebuffer. Basically,
this means that you don't have access to its bound color,
stencil and depth buffers. We need to handle this framebuffer
differently since its textures are always bound.

@private
@type {boolean}
@default false