Re: [Paracomp-devel] Crash in pcSystemFinalize

[Shree K. <shr...@hp...>]

Hi Stephen,

On Tue, 2008-05-13 at 11:34 +0000, Stefan Eilemann wrote:
> It seems my bad conscience carried over to you. I just remembered
> this, as I am currently integrating a patch for CPU-based assembly
> used in our volume renderer. As soon as I have checked this in, I'll
> get back to try PC.

Sure, do let me know.

> Iirc the crash was solved, and I was about to retest the performance
> issue. The last time I wanted to test it, sourceforge went down and
> then I promptly forgot it. :-/

Is this happening with sourceforge often ? I've been away for more than
a week now, so can't help wondering.

> I'll send you a link to the alpha-compositing patch. We do things not
> quite straight-forward in order to support colored backgrounds in
> eVolve. Basically we blend as if using glBlendFuncSeparate( GL_ONE,
> GL_SRC_ALPHA, GL_ZERO, GL_SRC_ALPHA ).

Do you have the background as a separate image which you composite with
the volume rendering in the end ?  This is possible.

Paracomp implements a back to front alpha blending. Images are assumed
to have pre-multiplied alpha.  Images contribute (1-alpha_front)*color
to the images in front of them. Basically this is the the same as stock
OpenGL.

Cheers
-- Shree