[osg-users] Can't write to ALPHA component with custom fragment shader in RTT pass

Jean-Sébastien Guay jean-sebastien.guay at cm-labs.com
Mon Mar 9 09:06:00 PDT 2009

Hi Jim,

> Not necessarily.  If the object-that-is-supposed-to-be-transparent
> still has depth writing enabled, it will overwrite more distant objects.
> Then there's which blend functions are enabled which
> can alter the output of the fragment shader.

OK, but I'm talking about a pre-render pass to an FBO though. The FBO is 
attached to an RGBA texture, and we want to be able to store some data 
in the alpha channel... So we want what we write to gl_FragColor.a to 
make it into the texture directly. Is there a way to do that?

(in effect, we want to be able to write to 4 floats per fragment)


Jean-Sebastien Guay    jean-sebastien.guay at cm-labs.com

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