From: MLM Veraart (veraart++at++fel.tno.nl)
Date: 12/02/2002 10:14:26
"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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