_getDefaultCubeTextureGPU( format ) {

		let defaultCubeTexture = this.defaultTexture[ format ];

		if ( defaultCubeTexture === undefined ) {

			const texture = new CubeTexture();
			texture.minFilter = NearestFilter;
			texture.magFilter = NearestFilter;

			this.createTexture( texture, { width: 1, height: 1, depth: 6 } );

			this.defaultCubeTexture[ format ] = defaultCubeTexture = texture;

		}

		return this.backend.get( defaultCubeTexture ).texture;

	}
Returns the default GPU cube texture for the given format.

@private
@param {string} format - The GPU format.
@return {GPUTexture} The GPU texture.