Norman Vine writes:
> Curtis L. Olson writes: 
> > We might need to learn more about how the imposters are rendered.  I
> > don't think this is an issue of drawing the imposter once it is
> > generated, but in generating the imposter in the first place.
> 
> The Impostors are generated with regular OpenGL calls just
> like everything else and then read out of the back buffer into
> a texture which then serves as an 'impostor' for the real OpenGL
> object.  eg you are substituting a glQuad for the entire set of 
> calls that were made to draw the object initially.  hence the
> name 'impostor'.  
> 
> You can see the impostors getting created after you find and follow
> the directions in this line in SkyCloud.cpp
> // Uncomment this swap buffers to visualize cloud illumination computation.
> 
> Whatching these things get created gives you a GOOD ideaof how much
> work the 'impostor' is saving you

Mark Harris mentioned that the back buffer requires a "destination
alpha" for imposter rendering to work.  Perhaps that's why things
aren't great with a 16bit color buffer, you probalby aren't even
getting an alpha channel there?

Regards,

Curt.
-- 
Curtis Olson   IVLab / HumanFIRST Program       FlightGear Project
Twin Cities    [EMAIL PROTECTED]                  [EMAIL PROTECTED]
Minnesota      http://www.menet.umn.edu/~curt   http://www.flightgear.org

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