From: mnippere++at++csc.com.au
Date: 12/02/2002 15:38:59
Remodeling the skydome is not a big problem. If you have the unit sized sky
dome that was mentioned earlier, all you have to do is scale it to half way
between the near and far clip plane with a matrix transformation. This
ensures that the dome will always be visible. And it allows you to move the
far clip plane, or the near clip plane for that matter if the need arises.
Matthew
"MLM Veraart" <veraart++at++fel.tno.nl> on 03/12/2002 04:14:26
To: "Corner Steve" <s.corner++at++vr-centre.com>
cc: info-performer++at++sgi.com
Subject: Re: [info-performer] overriding the clipping plane
"Corner, Steve" wrote:
>
> So long as the sky dome object is within the near and far clip planes it
> will visually be draw at the far clip plane, because your not writing
into
> the z-buffer, which should have just been cleared to the value of the far
> clip plane.
>
> S.
Brad had to adjust the far clip plane to get a good render rate but then he
lost the sky-dome. So he HAS to remodel the dome to see it or use a
different trick.
Mario
>
> -----Original Message-----
> From: MLM Veraart [mailto:veraart++at++fel.tno.nl]
> Sent: 02 December 2002 13:54
> To: Corner Steve
> Cc: info-performer++at++sgi.com
> Subject: Re: [info-performer] overriding the clipping plane
>
> "Corner, Steve" wrote:
> >
> > turn off z-buffering
> > render sky dome
>
> I think the clipping routines in the graphics pipe will clip the dome
> if you use this method.
> By disabling the Z-buffer you don't eliminate the far clipping plane.
> You might try to setup a different projection matrix while drawing the
dome.
> But in essence this might be as much work (draw time) as using a second
> channel.
>
> Mario
>
> > turn on z-buffering
> > render the rest of the scene.
> >
> > you only have to clear the z-buffer each frame too....
> >
> > S.
> >
> > -----Original Message-----
> > From: MLM Veraart [mailto:veraart++at++fel.tno.nl]
> > Sent: 02 December 2002 12:31
> > To: Brad Schwagler
> > Cc: info-performer++at++sgi.com
> > Subject: Re: [info-performer] overriding the clipping plane
> >
> > Brad Schwagler wrote:
> > >
> > > I have a driving simulator with many objects in the
> > > scenegraph. If I make the clipping plane closer,
> > > distant objects are not drawn and the program runs at
> > > an acceptable drawing rate. This is what I want, but
> > > how can I still draw the sky-dome? I tried setting a
> > > pre-draw callback on the sky model where I would
> > > temporarily move back the clipping plane. The problem
> > > is that the channel and pipe are NULL in the callback
> > > func. Would it be better to use hundreds of LOD nodes
> > > on each indvidual object instead? Is there a
> > > different way of overriding the clipping plane?
> > > thanks
> >
> > There are two ways I know to solve this.
> >
> > 1) remodel the dome a bit smaller
> >
> > 2) Put the dome in a separate pfScene.
> > Use an other channel mapped 'behind'/first to the window.
> > In this channel put the dome scene and set the clipping range right.
> > In the other scene disable the clearing of frame and Z-buffer in the
> > draw-callback.
> >
> > Mario
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