Re: [Paracomp-devel] Crash in pcSystemFinalize

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

Hi Stefan,

Stefan Eilemann wrote:
> On 13. May 2008, at 13:34, Stefan Eilemann wrote:
>
>   
>> 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 ).
>>
>> Can I do this with ParaComp as well?
>>     
>
> Here you go: <http://equalizer.svn.sourceforge.net/equalizer/?rev=1879&view=rev
>  >
>   
I just updated my sandbox to get the changes. I think it's fairly easy 
to add support
for the sort of compositing you are looking for. I had a good look at 
the code : changing the blending equation
is quite easy in the C code. In the assembly language code for x86_64, 
the number/type of instructions remain the same :-)

Quick preliminary tests on my x86_64 desktop (these are with the wrong 
blending equation, but I expect the same to
hold on the correct blending equation too)
------ Without Paracomp ------
./Linux/test: Alpha first op:  66.7899 ms (394.778 MB/s)
./Linux/test: Alpha second op: 69.5435 ms (379.147 MB/s)
./Linux/test: Alpha 15 images: 307.675 ms (428.491 MB/s)
-------- With Paracomp ---------
./Linux/test: Alpha first op:  40.5636 ms (650.021 MB/s)
./Linux/test: Alpha second op: 51.9242 ms (507.802 MB/s)
./Linux/test: Alpha 15 images: 152.929 ms (862.071 MB/s)
--------------------------------------

Small note : test.cpp isn't using alpha blending in the "Alpha 15 
images" case. This is due to a missing "true" parameter to
 assembleFramesCPU. In line 108, you need to add a true param to 
assembleFramesCPU()

I'll change the blending function as an experiment on monday & send you 
some patches.

Note to myself : How to provide the same functionality as a standardized 
function in paracomp.

Cheers
-- Shree