[HOpenGL] MacOSX accumulation buffer.

Corey O'Connor coreyoconnor at gmail.com
Tue Jan 27 13:34:53 EST 2009


Not I.:-\ Last time I tried I used some hefty desktop graphics cards
too. That was several years ago when this technote definitely applied:
http://developer.apple.com/technotes/tn/tn2014.html#Section10

"Mac OS X also supports AUX (auxiliary) buffers and an 8-bit stencil
buffer. Accumulation buffers are not supported in hardware on Mac OS
X."

Cheers,
Corey O'Connor

On Tue, Jan 27, 2009 at 10:21 AM, Sebastiaan Visser <sfvisser at cs.uu.nl> wrote:
> Hello,
>
> Maybe my question is not really related to the HOpenGL library in
> particular, but more general a MacOSX+OpenGL problem. I hope some of you
> guys recognize this issue.
>
> It seems there is no way to get the accumulation buffer to work efficiently
> on MacOSX. Using this buffer to implement a neat motion blur slows down the
> framerate to less than 8 fps on my machine. A brand new Macbook with the
> newest NVIDIA GeForce 9400M running a very simple demo with just one 3D
> torus.
>
> I am using this initialization code:
>
>> initialDisplayMode $= [
>>     ...
>>   , WithAccumBuffer
>>   ]
>>
>> initialDisplayCapabilities $= [
>>     ...
>>   , Where DisplayAccA IsEqualTo 8 -- Also tried 1, 16, 24, 32...
>>   ]
>
> And use the buffer like this:
>
>> withMotionBlur comp = do
>>   accum Mult 0.95
>>   comp
>>   accum Accum 0.05
>>   accum Return 1.2
>
> The result looks verry pretty but is terribly slow.
>
> Is there someone how has ever used the accumulation buffer on MacOSX without
> experiencing slowdowns?
>
> Thanks,
>
> --
> sebastiaan
>
>
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