height = rect.height + 'px';

        const gpu = new PreProcessor( canvas3d );

        let media = null;

        function toggleSource()
        {
            if( media === video )
            {
                image.parentElement.classList.remove( 'hide' );
                video.parentElement.classList.add( 'hide' );
                media = image;
            }
            else
            {
                image.parentElement.classList.add( 'hide' );
                video.parentElement.classList.remove