Create a clip-path animated ?

Hi,

I would like to use a rectangle that move (left to right) to reveal an element / image

like this

The white box shall be the image to display

But I'm already block at my svg animation

<svg viewBox="0 0 265.135 68.642" xmlns="http://www.w3.org/2000/svg">
<g x="-55.790085" y="0.79151762">
    <rect
       style="fill:#ffcc00;stroke-width:2.46513;stroke-linecap:round;stroke-linejoin:round;paint-order:stroke fill markers;stop-color:#000000"
       width="55.465603"
       height="151.60599"       
       transform="rotate(45)" />
       <animate
      attributeName="x"
      values="-55.790085;265"
      dur="5s"
      repeatCount="indefinite" />
  </g>
</svg>

Because the rectangle is not moving :'(

Any ideas ?

Thanks.