OpenGL

useful.glsl

Source: https://www.opengl.org/discussion_boards/showthread.php/173019-View-Space-Light-Position-Moving

vec3 PositionFromDepth_DarkPhoton(in float depth)
{
  vec2 ndc;             // Reconstructed NDC-space position
  vec3 eye;             // Reconstructed EYE-space position
 
  eye.z = near * far / ((depth * (far - near)) - far);
 
  ndc.x = ((gl_FragCoord.x * widthInv) - 0.5) * 2.0;
  ndc.y = ((gl_FragCoord.y * heightInv) - 0.5) * 2.0;
 
  eye.x = ( (-ndc.x * eye.z) * (right-left)/(2*near)
            - eye.z * (right+left)/(2*near) );
  eye.y = ( (-ndc.y * eye.z) * (top-bottom)/(2*near)
            - eye.z * (top+bottom)/(2*near) );
 
  return eye;
}