Re: pfLightPoint

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Allan Schaffer (aschaffe)
Mon, 23 Jan 1995 11:03:00 -0800

On Jan 23, 11:41am, Rejean Chartrand wrote:
>
> How, using pfLightPoint, can I create light points that covers more
> than one pixel on an Indigo machine since the size passed to the
> pfLPointSize is passed to the pntsizef GL routines. The man pages for
> pntsizef clearly specify that :
>
> The maximum size of aliased points is 255.
>
> IRIS-4D VGX model supports antialiased point sizes 1.0 and
> 2.0, and aliased point sizes one through 255. IRIS-4D GT and
> GTX models support antialiased point size 1.0, and aliased
> point sizes one and two. IRIS-4D G mods, Personal Iris, Iris
> Entry, Indy, XL, XS, XS24, XZ, Elan and Extreme systems
> support only point size one.

There doesn't appear to be an easy workaround, since the lightpoint
PFGS_POINTS geosets drawn use pfGSetPntSize (and correspondingly,
pntsizef) to control their size. The pntsizef() restrictions noted
in the man page are due to hardware limitations.

With Performer 2.0 you'll be able to use (OpenGL) glPointSize
routine, which is supported on all platforms (in software when
necessary).

A hackish alternative may be to draw filled circles in the draw
callback for the lightpoint (keeping the lightpoint node in the scene
graph so as to be properly effected by DCS/SCS nodes, etc). Or more
outlandish, it may be possible to remove the PFGS_POINTS geosets from
the pfLightpoint nodes and add small quads or tris to be drawn
instead. It may then be necessary to do some special tricks so that
the spoofed lightpoints will be properly attenuated by the fog.

> I've been asking the same question for a long time but never got any
> response to it; perhaps somebody from SGI can answer me.

We're happy to respond when we can. Don't forget that info-performer
is an informal service, though, so when you need a guaranteed
response it's sometimes better to use the support hotline or other
"official channels".

Allan

-- 
Allan Schaffer
Silicon Graphics
aschaffe++at++sgi.com
http://reality.sgi.com/employees/aschaffe

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