Yep, I don't think __alpha is defined when building on more modern machines (didn't know the history behind it, though. Thanks Jonathan)
Ben, thanks for the credit, but this is not what I meant in the original post. What I was trying to say was that the original issue Ron posted was due to filters acting on a square region. If you're applying a large blur to something like a circle, pixels will still be filtered based on a square region. This is generally ok, since the pixels at the corners of your image (further from the center of the circle) will be filtered using a lot more black samples than, say, any other pixels along the sides of the image (which would be closer to the circle). So, they'll get smaller values, as you would expect. The problem comes when you push those smaller values (with a gamma operation, for example) far enough that they start getting close to any other value in the image. Then you end up with a "square", as Ron's example was showing. Hope that makes more sense. :) Cheers, Ivan On Wed, Oct 5, 2011 at 2:29 PM, Jonathan Egstad <jegs...@earthlink.net>wrote: > > -------snip---------- > > > > float G = gamma[z]; > > // patch for linux alphas because the pow function behaves badly > > // for very large or very small exponent values. > > #ifdef __alpha > > if (G < 0.008f) > > G = 0.0f; > > if (G > 125.0f) > > G = 125.0f; > > #endif > > > > -------snip----------- > > I might be wrong, but I think this clamp patch is only enabled when built > on on DEC Alpha machines. You may want to double-check that the __alpha > token gets enabled during a build on an Intel machine. > > For those interested in Nuke history - the DEC Alpha was one of the first > Linux boxes used in production at Digital Domain back in the mid '90s and > Nuke ran like blazes on them compared to the relatively pokey SGIs. > > -jonathan > > _______________________________________________ > Nuke-users mailing list > Nuke-users@support.thefoundry.co.uk, http://forums.thefoundry.co.uk/ > http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users >
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