pfLayers & Flickering in 2.0

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Todd R Pravata (tpravata++at++rts.dseg.ti.com)
Mon, 19 Feb 96 10:02:35 CST


FYI ...

I've run into the same problems with the S1K Loader using DISPLACE and
FAST (same comments apply wrt near/far clip and orientation). In
addition, I've found that the following from the pfLayer man page
(which specifically addresses orientation with respect to the
eyepoint) does not give any better results. I have to go to STENCIL
to get good results for an IGL compile. I have not tried the OGL
version.

          PFDECAL_BASE_DISPLACE | PFDECAL_LAYER_OFFSET
               Use slope-based polygon displacement to slightly displace the
               depth values of decal geometry closer to the eye so they have
               visual priority. In addition, decal geometry is offset a
               constant amount to eliminate anomalies caused by geometry which
               is nearly perpendicular to the view. Each decal is displaced
               and offset more than its predecessor to properly resolve
               priority between decals. The maximum number of decals is 8.

> > I have tried every PFDECAL_* with pfdConverterMode_flt and none of them
> > seem to do any thing. I even called pfdGetConverterMode_flt before
> > loading the model to check that the Mode was correct. I tried to use
> > pfdCombineLayers() after every thing was loaded. Still nothing. I have
> > run on both an Indigo2 and an Onyx and both have really bad flickering.
> > When I look at the database in perfly, it looks fine.
>
> I have tested both executables, /usr/sbin/perfly_igl and /usr/sbin/perfly_ogl,
> on my Indigo2 XZ with 5.3 and patches 183, 258, 342, 358, 420, 450, 453, 526,
> and 541 among others. The IRIS GL version behaves very badly as you describe,
> when using _FAST or _DISPLACE modes. Quality varies greatly as a function of
> the near/far clipping planse and also the position/orientation of the layer'd
> geometry wrt the eyepoint. Conversely, the OpenGL version behaves quite well
> given the same circumstances.

--
Todd Pravata		
todd.pravata++at++ti.com  214-575-6126
Visual Simulation Lab, Texas Instruments

"It is not enough to be busy; so are the ants. The question is: what are we busy about?" -- Thoreau

** Views expressed are not necessarily those of Texas Instruments **


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