title: Three.js - how can i use fixed background image as environment map for 3d model
body: <p>i was looking at some models on sketchfab and i found many models have texture that are from background.</p>
  <p>I know how to use cubecamera and render target to simulate refraction and transparency in three.js but how can i achive this look with fixed background that is not moving like a cube.</p>
  <p>example:
  <a href="https://sketchfab.com/3d-models/diamond-4c31bb47a726423c8db8ecc9c5cd35dc" rel="nofollow noreferrer">https://sketchfab.com/3d-models/diamond-4c31bb47a726423c8db8ecc9c5cd35dc</a></p>
  <p>see how fixed background is applied on that object as you move it around like transparency.</p>
  <p>Can you do this without shader or you have the use one and how?
  Thanks.</p>