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I use sunpos.inc for lighting. The position of the sun is calculated in one
direction and then translated and rotated by an equation. How can I find the
exact position of the sun for effect_location variable, which is used by the
popular lnsefcts.inc?
Istvan
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From: Mike
Subject: Re: Finding exact position after translating and rotating...
Date: 18 Dec 1998 17:36:31
Message: <367B737F.1F700759@aol.com>
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You could #declare the variables you use for the sun postition and then
use that anywhere you want.
-Mike
>
> I use sunpos.inc for lighting. The position of the sun is calculated in one
> direction and then translated and rotated by an equation. How can I find the
> exact position of the sun for effect_location variable, which is used by the
> popular lnsefcts.inc?
>
> Istvan
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From: ingo
Subject: Re: Finding exact position after translating and rotating...
Date: 18 Dec 1998 18:11:30
Message: <367ae122.0@news.povray.org>
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Mike heeft geschreven in bericht <367B737F.1F700759@aol.com>...
>You could #declare the variables you use for the sun postition and then
>use that anywhere you want.
I don't think that is what Istvan is looking for. The problem, as I
understand it, is how to go from
light_source {
<0,0,0>
translate <0, 0, SunDistance>
rotate <-Al, Az, 0>
}
to an exact position: light_source {<x,y,z>}.
Although I've put together the sunpos.inc (I needed it badly) my math is not
as good as it has never been before
Sorry I cant help you on this, maybe someone else?
ingo
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From: Margus Ramst
Subject: Re: Finding exact position after translating and rotating...
Date: 18 Dec 1998 19:04:09
Message: <367AEC17.CE0504EF@peak.edu.ee>
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I haven't used sunpos.inc, but if you need the position vector of a
translated/rotated point, you can get it with vector functions. For example,
vrotate(<XTrans,YTrans,ZTrans>,<XRot,YRot,ZRot>) returns the new coordinates
of a point <XTrans,YTrans,ZTrans> rotated around the origin by
<XRot,YRot,ZRot>.
Just apply the same translation/rotation as the ones in sunpos and you get the
point you need.
Margus
>
> I use sunpos.inc for lighting. The position of the sun is calculated in one
> direction and then translated and rotated by an equation. How can I find the
> exact position of the sun for effect_location variable, which is used by the
> popular lnsefcts.inc?
>
> Istvan
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From: Jerry Anning
Subject: Re: Finding exact position after translating and rotating...
Date: 18 Dec 1998 22:53:52
Message: <367B235D.3A7E8FA3@dhol.com>
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>
> I use sunpos.inc for lighting. The position of the sun is calculated in one
> direction and then translated and rotated by an equation. How can I find the
> exact position of the sun for effect_location variable, which is used by the
> popular lnsefcts.inc?
>
> Istvan
Add the following line to sunpos.inc immediately before the #end:
#declare Sunloc = vrotate(<0, 0, 1000000000>, <-Al, Az, 0>;
This will cause the macro to put the Sun's location into the global
variable Sunloc, enabling you to use it as you wish (e.g. #declare
effect_location = Sunloc;) It will not change the function of
sunpos.inc in any other way.
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From: Mike
Subject: Re: Finding exact position after translating and rotating...
Date: 18 Dec 1998 23:33:40
Message: <367BC732.B45C2276@aol.com>
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What I meant was, to go with your example:
#declare SunDistance = <0, 0, 5> //arbitrary units of course :)
#declare SunPosition = vrotate (Sundistance, <-Al, Az, 0>)
light_source {SunPosition color something}
#declare effect_location = SunPosition
-Mike
ingo wrote:
>
> Mike heeft geschreven in bericht <367B737F.1F700759@aol.com>...
> >You could #declare the variables you use for the sun postition and then
> >use that anywhere you want.
>
> I don't think that is what Istvan is looking for. The problem, as I
> understand it, is how to go from
>
> light_source {
> <0,0,0>
> translate <0, 0, SunDistance>
> rotate <-Al, Az, 0>
> }
>
> to an exact position: light_source {<x,y,z>}.
>
> Although I've put together the sunpos.inc (I needed it badly) my math is not
> as good as it has never been before
>
> Sorry I cant help you on this, maybe someone else?
>
> ingo
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