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From: Slime
Subject: Constant width grid
Date: 8 Jul 2006 20:50:26
Message: <44b052d2@news.povray.org>
See "Re: TRON Game Grid..." in povray.newusers. The grid lines get bigger as
they get farther away from the camera.

 - Slime
 [ http://www.slimeland.com/ ]


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From: Carl
Subject: Re: Constant width grid
Date: 9 Jul 2006 11:20:01
Message: <web.44b11d3fe4538ab647c7ed100@news.povray.org>
"Slime" <fak### [at] emailaddress> wrote:
> See "Re: TRON Game Grid..." in povray.newusers. The grid lines get bigger as
> they get farther away from the camera.
>
>  - Slime
>  [ http://www.slimeland.com/ ]

Nice work, far better then I could do but its still missing something.

http://www.wwwmwww.com/Matt/grid5.png

Refering to the above, things look about correct when the camera is looking
at 45 degrees to the grid lines (the black arrow).  However when the camera
is looking down one of the grid lines (as it is with the red arrow) the
effect looks backwards.  The grid line should narrow in this direction and
you can see that it doesn't.  Also the grid lines perpendicular to this one
shouldn't narrow with distance near as much as they do.

Check out this frame from the film:

http://www.wwwmwww.com/Matt/grid.png

Note when you are looking parallel to the grid lines its the perpendicular
ones that bleed together and not the not the ones that you are looking
along that are merging.

To prove that the grid lines narrow about correctly when the camera looks
along them look at this:

http://www.wwwmwww.com/Matt/grid4.png

The top image is a frame from TRON.  The bottom image is a POV-Ray sceen
rendered using the grid I posted in "Re: TRON Game Grid..." in
povray.newusers.

Carl


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From: Slime
Subject: Re: Constant width grid
Date: 9 Jul 2006 18:37:30
Message: <44b1852a$1@news.povray.org>
The effect I was trying to create was grid lines that don't get thinner as
they go off into the distance. As you point out, it doesn't appear that TRON
used that sort of effect after all.

Looking at the last image you linked to (grid4.png), I don't believe there
is any sort of effect being applied at all. The reason your image doesn't
fade to white at the horizon like the original does is a lack of
anti-aliasing - rays are not hitting the white lines often enough to know
they're there. Try AA settings +AM2 +A0.0 +R3 and see what sort of results
you get.

 - Slime
 [ http://www.slimeland.com/ ]


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From: Carl
Subject: Re: Constant width grid
Date: 9 Jul 2006 21:15:00
Message: <web.44b1a9a2e4538ab647c7ed100@news.povray.org>
"Slime" <fak### [at] emailaddress> wrote:
> Looking at the last image you linked to (grid4.png), I don't believe there
> is any sort of effect being applied at all. The reason your image doesn't
> fade to white at the horizon like the original does is a lack of
> anti-aliasing - rays are not hitting the white lines often enough to know
> they're there. Try AA settings +AM2 +A0.0 +R3 and see what sort of results
> you get.
>
>  - Slime
>  [ http://www.slimeland.com/ ]

The AA is quite high in that last image already. I think that one was made
with +AM2 +A0.0 +R4. I've played with this enough to know that there is
more going on in the TRON images then just AA.  For example the grid fades
to all white... not all black as it should.  Remember the white grid lines
only cover about 2% of the grid surface.  The perpandicular grid lines are
certainly getting wider with distance from the camera.  So much so that the
surface is all white just a few grid squares away from the camera in that
last shot.

Carl


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From: EagleSun
Subject: Re: Constant width grid
Date: 9 Jul 2006 23:00:00
Message: <web.44b1c201e4538ab6c5cc1b060@news.povray.org>
"Slime" <fak### [at] emailaddress> wrote:
> See "Re: TRON Game Grid..." in povray.newusers. The grid lines get bigger as
> they get farther away from the camera.
>
>  - Slime
>  [ http://www.slimeland.com/ ]

Looks like there is no width to the lines, which means POV-Ray doesn't know
what to do with it, producing the white-out in the distance.  Suppose you
define a width to the line.. say 1 mm or something small... then the lines
should get thinner near the horizon.


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From: Zeger Knaepen
Subject: Re: Constant width grid
Date: 10 Jul 2006 03:26:39
Message: <44b2012f@news.povray.org>
"Carl" <car### [at] semisouthcom> wrote in message 
news:web.44b1a9a2e4538ab647c7ed100@news.povray.org...
> The AA is quite high in that last image already. I think that one was 
made
> with +AM2 +A0.0 +R4.

I might be mistaken, but don't you loose the adaptive advantage of +am2 
if you have +a0.0 ?

cu!
-- 
#macro G(b,e)b+(e-b)*C/50#end#macro _(b,e,k,l)#local C=0;#while(C<50)
sphere{G(b,e)+3*z.1pigment{rgb G(k,l)}finish{ambient 1}}#local C=C+1;
#end#end _(y-x,y,x,x+y)_(y,-x-y,x+y,y)_(-x-y,-y,y,y+z)_(-y,y,y+z,x+y)
_(0x+y.5+y/2x)_(0x-y.5+y/2x)            // ZK http://www.povplace.com


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From: Carl
Subject: Re: Constant width grid
Date: 10 Jul 2006 10:30:01
Message: <web.44b263b7e4538ab670dc520d0@news.povray.org>
"Zeger Knaepen" <zeg### [at] povplacecom> wrote:
> I might be mistaken, but don't you loose the adaptive advantage of +am2
> if you have +a0.0 ?

Yes you do but if you have a very thin line going through a pixel it could
easily be missed all together if its set to anything else.

Carl


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From: Sebastian
Subject: Re: Constant width grid
Date: 10 Jul 2006 10:58:41
Message: <pan.2006.07.10.14.58.40.195712@gmx.de>
> The AA is quite high in that last image already. I think that one was made
> with +AM2 +A0.0 +R4. I've played with this enough to know that there is
> more going on in the TRON images then just AA.  For example the grid fades
> to all white... not all black as it should.  Remember the white grid lines
> only cover about 2% of the grid surface.  The perpandicular grid lines are
> certainly getting wider with distance from the camera.  So much so that the
> surface is all white just a few grid squares away from the camera in that
> last shot.

I guess the blurred grid effect in TRON is due to MIP-Mapping
http://en.wikipedia.org/wiki/Mipmap
I remember to have seen blurred textures in the far in
some games. To reproduce this with just the SDL should be
some work, especially when trilinear filtering on the edges 
between different LOD images is desired.

Sebastian


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From: M a r c
Subject: Re: Constant width grid
Date: 10 Jul 2006 11:21:15
Message: <44b2706b$1@news.povray.org>

pan### [at] gmxde...
>
> I guess the blurred grid effect in TRON is due to MIP-Mapping
> http://en.wikipedia.org/wiki/Mipmap

I see at the end of the wikipedia page that MIP-Mapping was invented by
Lance William in 1983
TRON was out in 1982
Maybe Lance William invented time travel as well? ;-)

Marc


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From: Sebastian
Subject: Re: Constant width grid
Date: 10 Jul 2006 12:24:17
Message: <pan.2006.07.10.16.24.12.893609@gmx.de>
>>
>> I guess the blurred grid effect in TRON is due to MIP-Mapping
>> http://en.wikipedia.org/wiki/Mipmap
> 
> I see at the end of the wikipedia page that MIP-Mapping was invented by
> Lance William in 1983
> TRON was out in 1982
> Maybe Lance William invented time travel as well? ;-)

Hmm, good point. :-)


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