title: How to save a value inside a fragment shader to use it later?
body: <p>I want to save a calculated value from fragment shader in some variable ,so that I would be able to use it next time.</p>
  
  <p>Currently, I am preparing a image using a huge algorithm and I want to save it to some vec4 and , once requested again , I want to just get that vec4 and should say</p>
  
  <p><code>gl_FragColor = vec4(previously saved variable)</code></p>
  
  <p>This question is related to another <a href="https://stackoverflow.com/questions/38178723/how-to-apply-multiple-image-processing-in-webgl-with-two-or-more-separate-color">question here</a> which is also asked by me , but I feel that if this question has a answer then I can easily crack the other one.</p>
  
  <p>Any suggestions ?</p>