title: SceneKit: how to transform content of SCNMaterial?
body: <p>I create SCNNode with SCNBox,</p>
  <pre><code>SCNBox *wallBox = [SCNBox boxWithWidth:width height:100 length:4 chamferRadius:0];
  
  SCNMaterial *allMaterial = [SCNMaterial new];
  allMaterial.diffuse.contents = @&quot;allwall.png&quot;;
  
  SCNMaterial *smallMaterial1 = [SCNMaterial new];
  smallMaterial1.diffuse.contents =@&quot;bottomwall.png&quot;;
          
  SCNNode *rightwall = [SCNNode nodeWithGeometry:wallBox];
          
  rightwall.geometry.materials = @[smallMaterial1,allMaterial,smallMaterial1,allMaterial,allMaterial,allMaterial];
  </code></pre>
  <p>but the back of texture direction is wrong.</p>
  <p><img src="https://i.stack.imgur.com/nB0oZ.png" alt="enter image description here" /></p>
  <p><img src="https://i.stack.imgur.com/d14Xq.png" alt="enter image description here" /></p>
  <p>I  want two direction is same,how to transform content of  SCNMaterial ? how to use &quot;contentsTransform&quot;?</p>