Correcting Outerra's Logarithmic Depth Buffering
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`Outerra has a vertex shader implementation of log depth buffering in GLSL <https://outerra.blogspot.com/2013/07/logarithmic-depth-buffer-optimizations.html>`_. However, Outerra missed a major part of their log depth buffering. This is our corrected version of Outerra’s log depth buffering in HLSL.

Outerra missed a multiply in the end. We must multiply log depth by ``W`` because the GPU automatically divides the vertex position ``HPos`` by ``W``.

Source Code
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::

   // Output.HPos is the computed vertex position in homogeneous space
   const float FarPlane = 10000.0;
   const float FCoef = 1.0 / log2(FarPlane + 1.0);
   Output.HPos.z = saturate(log2(max(1e-6, Output.HPos.w)) * FCoef);
   Output.HPos.z *= Output.HPos.w;