From: Allan Schaffer (allan++at++sgi.com)
Date: 05/31/2003 15:33:40
Bo Sun wrote:
> We have one SGI Reality engine, which installed two
> versions of irix.
>
> 1) with irix 6.2, performer 2.0 is installed;
> 2) with irix 6.5, performer 2.2 is installed.
>
> We have a set of code which is developed under irix
> 6.2. These codes works well under irix 6.2. The code
> is used to simulate an airport.
>
> But when we compile & run the same code under irix
> 6.5, the runway of the airport keeps flickering. In
> detail, there are several markings in the runway, and
> the markings keep flickering.
>
> I checked the performer manual, which tells me to use
> Decal mechanism to avoid flickering. I do have
> followed the manual, but still cannot avoid the
> flickering problem. Is there any compatibility problem
> between performer 2.0 and 2.2?
Something that comes to mind was the change in semantics for the
glPolygonOffset() routines from OpenGL 1.0 to OpenGL 1.1. I think an
upgrade from IRIX 6.2 (circa 1994) to IRIX 6.5 (1998) fits into this
timeframe. pfLayers (& decals) use glPolygonOffset.
We added some hidden controls to be able to revert to the OpenGL 1.0
behavior (when glPolygonOffset was an extension) in March 1999 - this
corresponds to approx Performer 2.2.4 / IRIX 6.5.4.
Try:
setenv PF_FORCE_ARB_POLYGON_OFFSET 1
or
setenv PF_FORCE_EXT_POLYGON_OFFSET 1
Additional controls (if using ARB) if you want additional control:
setenv PF_ARB_POLYGON_OFFSET_FACTOR x.x
setenv PF_ARB_POLYGON_OFFSET_UNITS y.y
Where x.x & y.y are values passed to glPolygonOffset (see the manpage).
Allan
-- Allan Schaffer allan++at++sgi.com Engr. Manager, Core Rendering 1-650-933-2160 Silicon Graphics http://www.sgi.com
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