title: Is a position buffer required for deferred rendering?
body: <p>I'm trying to avoid the uses of a Position Buffer by projecting Screen Space Points back into View Space to use with lighting. I have tried multiplying by the inverse projection matrix, but this does not give back the View Space point. Is it worth it to add matrix multiplication to avoid the Position Buffer?</p>
  
  <p>Final-pass Shader:</p>
  
  <pre><code>vec3 ScreenSpace = vec3(0.0,0.0,0.0);
  ScreenSpace.xy = (texcoord.xy * 2.0) - 1.0;
  ScreenSpace.z  = texture2D(depthtex, texcoord.xy);
  vec4 ViewSpace = InvProjectionMatrix * vec3(ScreenSpace, 1.0);
  ViewSpace.xyz = ViewSpace.w;
  </code></pre>