I finished benchmarking my new z buffer
which defers texturing and lighting until
after all the pixels have been depth sorted.
Each render was preceded with an srand(0) call
to ensure that all random number dependant
shading generated the exact same triangles.
Times for deferred rendering include iterating
through the light cache and computing the
final appearance of the scene. The scene was
a typical landscape using an ~ 500 x 500 pixel
heightfield. These results are preliminary
and I will be doing more tests as time goes on.

For a window size of 900 x 250, the difference
in speed was small, between 2 and 8 seconds on jobs
that ran between 1 and 2 minutes depending on LOD.
The texturing code in this case is very simple,
being just a colormap lookup; it represents a
small percentage of the total render pipeline.

Increasing the window size to 1800 x 500
changed things quite a bit:

    900 x 250        1800 x 500
  --------------   ---------------
   2m10s normal     6m05s normal
   2m02s deferred   5m35s deferred
      8s better       30s better

The time savings scaled proportionally
with the window size, but the render
time scaled less, resulting in greater
percentage time savings at the larger size.
With more screen pixels, the benefits of
deferred texturing increase.

I will be recompiling the Leveller Viewer
up to version 2.3 including the scanline
renderer for those who wish to evaluate
this particular scanline renderer implementation
with their own data.

Ray

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