RE: [Algorithms] Return of the front clip plane

[Tom F. <to...@mu...>]

Hmmmm... I like the idea in principle - only the very near stuff (which is
hopefully quite rare) gets the extra clipping stuff, and even when it does
happen, the normal and far distance stuff isn't affected. Unfortunately, any
clipping imprecision is going to be very obvious since the objects are so
close to the camera. It might be better to move the near clip plane a bit
further away in these cases, so that any imprecision is moved further away
from the camera.

So under normal circumstances, your NCP is, say, 10m away. If anything comes
closer than 10m, you do the clipping to a plane 50m away and do Hamilton's
two-frustum trick. Maybe that'll result in fewer possible tears along the
clip lines.

Tom Forsyth - Muckyfoot bloke.
Whizzing and pasting and pooting through the day.

> -----Original Message-----
> From: Feltman, Hamilton [mailto:Fe...@se...]
> Sent: 03 August 2000 21:26
> To: 'gda...@li...'
> Subject: RE: [Algorithms] Return of the front clip plane
> 
> 
> 
> So how does this sound:
> 
> - Create a frustum which matches your graphics API's frustum
> with the exception of the near plane; for this, use the minimum
> near plane you can handle.
> 
> - Clip world geometry (or a bounding version) to this frustum
> manually just like the good old days.
> 
> - Use the closest clipped point of "whatever is left after clipping"
> to the eye plane as the distance for the near plane for a new
> frustum, send this frustum to the graphics API, and draw the
> world geometry for this frame.
> 
> I'm sure it would work; is this the way you did it?
> 
> Hamilton Feltman
> SEGA AMUS/ARCADE
> www.sega.com/alienfront
> 
> > -----Original Message-----
> > From:	Tom Forsyth [SMTP:to...@mu...]
> > Sent:	Thursday, August 03, 2000 12:46 PM
> > To:	gda...@li...
> > Subject:	RE: [Algorithms] Return of the front clip plane
> > 
> > Moving the near (and possibly far - depends on your app) clip planes
> > dynamically works very well indeed. Yes, there is the 
> slight artifact that
> > walking past a tree affects the Z precision of the far-off 
> building that
> > you're actually looking at, but then it's pretty hard to 
> think of any
> > system
> > that will do it any better, apart from the Z-partition 
> trick (which is
> > expensive in some cases - though dead easy for flight sims).
> > 
> > Tom Forsyth - Muckyfoot bloke.
> > Whizzing and pasting and pooting through the day.
> > 
> > > -----Original Message-----
> > > From: Steve Wood [mailto:Ste...@im...]
> > > Sent: 03 August 2000 20:09
> > > To: 'gda...@li...'
> > > Subject: RE: [Algorithms] Return of the front clip plane
> > > 
> > > 
> > > > -----Original Message-----
> > > > From: Jason Zisk [mailto:zi...@n-...]
> > > > 
> > > > Another solution is to just make your player's bounding 
> > > > volume larger so you can't get close enough to stuff to
> > > > clip into it, this works okay but I find that you have 
> > > > to keep the player from getting closer than 3 units with 
> > > > a 1 unit clip because of viewport rotation (just keeping the 
> > > > player 1 unit away is fine if you are staring straight at a 
> > > > wall but as soon as you rotate the edges of your viewport 
> > > > will clip it).
> > > > 
> > > 
> > > For my FPS I used a wall that I walked up to then looked up 
> > > and down, then
> > > adjusted my collision detection to prevent the player's view 
> > > from clipping
> > > the wall simply because of the view angle.  It seems to 
> work fine...I
> > > wouldn't want to get into changing the viewport dimensions 
> > > cause wouldn't it
> > > distort the scene?  I'd reserve changing viewport dimensions 
> > > for special
> > > effects like underwater wooziness.
> > > 
> > > R&R
> > > 
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> > > 
> > 
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