Re: Multisample Masks
Lionel Maiaux (maiaux++at++corys.fr)
Wed, 26 Feb 1997 09:59:13 +0100
Rimi Arnaud wrote:
>
> Mark Baranowski wrote:
> >
> > Hi,
> >
> > I wan't to fade certain geometry in and out of my scene. I am running
> > on an Onyx iR Performer 2.1, Open GL compilation.
> >
> > It seems that it should be pretty straightforward to do using the
> > multisample mask in a pre&post draw callback for the nodes I wish to
> > fade (i.e. using glSampleMaskSGIS in a pre draw to effectively set the
> > level of transparency I want, and then reset the mask in a post draw).
> >
> > Will this work? (Isn't it how Performer implements it's fade LOD
> > feature) It seems much simpler than having to modify the alpha in
> > materials/colours associated with the geometry etc. Is there anything
> > I should be aware of wrt doing this?
> >
> > Any advice greatfully received.
> >
>
> Sure it will work if you also use:
> glEnable(GL_SAMPLE_MASK_SGIS); and glDisable...
>
> For optimisation, try not to call enable and disable in each callback.
> You can do it by grouping all objects that have to have that callback
> in a bin.
Wy should Mark use glDisable(GL_SAMPLE_MASK_SGIS) ?
Are there other performance reason to not only reset the mask in the
post draw (as Mark says) or in the pre draw of opaque geometries ?
------------------------------------------------------------------------
Lionel Maiaux
l.maiaux++at++corys.fr
------------------------------------------------------------------------
=======================================================================
List Archives, FAQ, FTP: http://www.sgi.com/Technology/Performer/
Submissions: info-performer++at++sgi.com
Admin. requests: info-performer-request++at++sgi.com
This archive was generated by hypermail 2.0b2
on Mon Aug 10 1998 - 17:54:44 PDT