[Radiance-general] Re: Trees in the holodeck

[Greg Ward]

Well, I spent a couple of hours on this, and I did find a bug for some 
vertical cylinders, but apparently this isn't the bug causing all the 
problems -- at least on my Mac OS X X11 server (Apple's public beta).  
I still get out-of-place cylinders, and when I look a bit closer and 
isolate the problem cases, they render just fine.  It's only when 
there's a whole bunch of geometry that the glu* routines in OpenGL seem 
to go whacky.  I've given up at this point.  If the bug is mine, I have 
no idea where it is or how it's coming about.  I'm reluctant to cop out 
and call it an OpenGL bug, but I don't think the quadric rendering 
routines are all that well tested, so it's a distinct possibility.  In 
any case, I'm giving up on it.  The glrad program also seems to be 
broken under OS X, and I have no idea why.  I wish there were some 
debugging tools for OpenGL, but it's all trial and error and too much 
error for me at this point.

-Greg

> From: Randolph Fritz <randolph@panix.com>
>
> On Saturday, May 24, 2003, at 09:28  AM, Greg Ward wrote:
>
>> I believe there's a bug either in the code that determines rotation 
>> angles for cylinders in src/common/rglsurf.c or many OpenGL 
>> implementations.  I suspect the former, but need to do some further 
>> investigation to figure it out for sure.
>
> Thanks.  The two OpenGL implementations are XFree86/x86 Radeon 7000 VE 
> and Apple X11 (beta3), Radeon 9000.  It's possible that the Radeon 
> drivers have bugs.
>
> Randolph