title: GLSL Shader: Mapping Bars in Polar-Coordinates
body: <p>I'd like to create a polar representation of this shader: <a href="https://www.shadertoy.com/view/4sfSDN" rel="nofollow">https://www.shadertoy.com/view/4sfSDN</a></p>
  
  <p>So that it looks like in this screenshot:
  <a href="http://postimg.org/image/uwc34jxxz/" rel="nofollow">http://postimg.org/image/uwc34jxxz/</a></p>
  
  <p>I know the basics of the polar-system: How to calculate r and ϕ, but i can only use those values with a texture2d() load function on a image.</p>
  
  <p>When i only have a amplitude value like in the shader above, i dont get it working.</p>
  
  <p>r should somehow be based of the amplitude, but then i dont know how to draw the circle without the texture2d() function... i can draw a circle with r only, but then there are no different amplitudes. Or do i even need to fill a matrix with the generated bars in a loop and load the circle from there?</p>
  
  <p>Im quite sure it is possible, because of the insane shaders on shadertoy, but i dont quite get it... 
  Can anyone point me out to a solution?</p>