On 11/06/2013 12:58 PM, Brian Paul wrote:
On 11/06/2013 12:34 PM, burlen wrote:
When I build osmesa with --with-osmesa-bits=32 I notice that I get 31
bits by way of the compile line define -DDEFAULT_SOFTWARE_DEPTH_BITS=31.
What's the story with the number 31? Is 31 bits really better than 32?

IIRC, 32 bit Z never worked properly because of float->int conversion problems and such. I think I found that 31 bits worked though. It's been a long time...


I'm using OSMesa with VTK for rendering on systems that do not have graphics hardware. I need higher than default depth buffer with OSMesa to prevent z-buffer fighting artifacts in some cases when rendering in parallel. I found that --with-osmesa-bits=32 does the trick. however when building osmesa with 32 bits, most line rendering fails. Here is a representative image diff from our regression suite that shows an example of the bug http://open.cdash.org/testDetails.php?test=216532438&build=3087854 , there are 80 other failed tests, the ones I examined were all the same.

Experimenting with --with-osmesa-bits options, I've found that using 32 causes the issue, while using 8 , 16 or not using it all doesn't. Do you have any idea about this?

Thanks
Burlen

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