title: How can I create a gadient background in Qt3D?
body: <p>I am looking for the C++ code that creates a gradient background (e.g. from black to white). Currently I only have a solid color by setting the clear color of Qt3DWindow:</p>
  
  <pre><code>Qt3DExtras::Qt3DWindow-&gt;defaultFrameGraph()-&gt;setClearColor(QColor(QRgb(0x4d4d9f)))
  </code></pre>
  
  <p>How can I make a gradient?</p>