title: Apply color gradient to material on mesh - three.js
body: <p>I have an STL file loaded into my scene with a single colour applied to a phong material</p>
  
  <p>I'd like a way of applying two colours to this mesh's material with a gradient effect applied on the Z axis a like the example below.<a href="https://i.stack.imgur.com/Ty9gq.jpg" rel="noreferrer">Gradient Vase</a>]<a href="https://i.stack.imgur.com/Ty9gq.jpg" rel="noreferrer">1</a></p>
  
  <p>I have a feeling I may have to introduce shaders but I've not gotten this far with three.js.  </p>