POV-Ray : Newsgroups : povray.newusers : Location, Location, Location Server Time
29 Jul 2024 18:23:05 EDT (-0400)
  Location, Location, Location (Message 1 to 10 of 10)  
From: waynehays1
Subject: Location, Location, Location
Date: 2 Jul 2005 22:45:00
Message: <web.42c75069a31f8c706a9959d70@news.povray.org>
What do the three numbers for Light Source Location represent?  I have
looked all over for this info, but to no avail.

Thanks


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From: Kyle
Subject: Re: Location, Location, Location
Date: 2 Jul 2005 23:31:36
Message: <shmec15fdvo4vccd0uv5hlid02v5gvki54@4ax.com>
You must not have looked in the manual!!!  Look here:

http://www.povray.org/documentation/view/3.6.1/246/

to get a description of the light_source.  Location is
self-explanatory, its a vector describing the location of the
light_source.

Look here:

http://www.povray.org/documentation/view/3.6.1/229/

for more info on vectors.  Look here:

http://www.povray.org/documentation/view/3.6.1/15/

for an explanation of POV-Ray's coordinate system.

That should pretty much cover it.


Kyle


On Sat,  2 Jul 2005 22:41:45 EDT, "waynehays1" <way### [at] yahoocom>
wrote:

>What do the three numbers for Light Source Location represent?  I have
>looked all over for this info, but to no avail.
>
>Thanks
>


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From: waynehays1
Subject: Re: Location, Location, Location
Date: 2 Jul 2005 23:55:01
Message: <web.42c76172501399066a9959d70@news.povray.org>
Maybe I'm slow but I still don't get it.  Are the three numbers x, y, z?  I
don't think so, but I cant tell what they are.

Wayne


Kyle <hob### [at] gatenet> wrote:
> You must not have looked in the manual!!!  Look here:
>
> http://www.povray.org/documentation/view/3.6.1/246/
>
> to get a description of the light_source.  Location is
> self-explanatory, its a vector describing the location of the
> light_source.
>
> Look here:
>
> http://www.povray.org/documentation/view/3.6.1/229/
>
> for more info on vectors.  Look here:
>
> http://www.povray.org/documentation/view/3.6.1/15/
>
> for an explanation of POV-Ray's coordinate system.
>
> That should pretty much cover it.
>
>
> Kyle
>
>
> On Sat,  2 Jul 2005 22:41:45 EDT, "waynehays1" <way### [at] yahoocom>
> wrote:
>
> >What do the three numbers for Light Source Location represent?  I have
> >looked all over for this info, but to no avail.
> >
> >Thanks
> >


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From: Kyle
Subject: Re: Location, Location, Location
Date: 3 Jul 2005 00:07:52
Message: <gqoec1tgsa3f26tmeljotr5ntnospj5l5h@4ax.com>
Yes, location is a vector <x, y, z> describing the position of the
light_source.  So, if you have the following code:

light_source { <10, 100, 20>, rgb<1, 1, 1> }

You're telling POV-Ray to place a white (rgb<1, 1, 1>) light_source at
the coordinates x=10, y=100, z=20.


Kyle


On Sat,  2 Jul 2005 23:54:26 EDT, "waynehays1" <way### [at] yahoocom>
wrote:

>Maybe I'm slow but I still don't get it.  Are the three numbers x, y, z?  I
>don't think so, but I cant tell what they are.
>
>Wayne
>
>
>Kyle <hob### [at] gatenet> wrote:
>> You must not have looked in the manual!!!  Look here:
>>
>> http://www.povray.org/documentation/view/3.6.1/246/
>>
>> to get a description of the light_source.  Location is
>> self-explanatory, its a vector describing the location of the
>> light_source.
>>
>> Look here:
>>
>> http://www.povray.org/documentation/view/3.6.1/229/
>>
>> for more info on vectors.  Look here:
>>
>> http://www.povray.org/documentation/view/3.6.1/15/
>>
>> for an explanation of POV-Ray's coordinate system.
>>
>> That should pretty much cover it.
>>
>>
>> Kyle
>>
>>
>> On Sat,  2 Jul 2005 22:41:45 EDT, "waynehays1" <way### [at] yahoocom>
>> wrote:
>>
>> >What do the three numbers for Light Source Location represent?  I have
>> >looked all over for this info, but to no avail.
>> >
>> >Thanks
>> >
>
>
>


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From: waynehays1
Subject: Re: Location, Location, Location
Date: 3 Jul 2005 00:10:00
Message: <web.42c76415501399066a9959d70@news.povray.org>
None of that info says what the three values are.  Is it x,y,z ???  I don't
believe it is, if I'm wrong, then I must not understand the units involved.
 I don't know why this seems so difficult, but it is.

Wayne


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From: Jim Charter
Subject: Re: Location, Location, Location
Date: 3 Jul 2005 00:28:01
Message: <42c76951@news.povray.org>
waynehays1 wrote:
> None of that info says what the three values are.  Is it x,y,z ???  I don't
> believe it is, if I'm wrong, then I must not understand the units involved.
>  I don't know why this seems so difficult, but it is.
> 
> Wayne
> 
> 
> 
> 
I guess we'll need to see your code and an explanation of what behavior 
seems odd to you in order to help.

If you use an example light source from the insert menu you may notice 
that a technique commonly used is to position the light at the origin 
then add a transform to give its real position.  If you copied a light 
from the insert menu then edited the location maybe you didn't notice 
the further "translate" in the code?


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From: waynehays1
Subject: Re: Location, Location, Location
Date: 3 Jul 2005 08:40:00
Message: <web.42c7dbf7501399066a9959d70@news.povray.org>
I think this is part of what is going on, but it just doesn't tell me what I
need to know.  I am sure it is here, but I just don't understand.  Thanks
for being patient with a noob.

camera {
  orthographic
  location <SCALE_FACTOR/2,SCALE_FACTOR,SCALE_FACTOR/2>
  up SCALE_FACTOR*z
  right SCALE_FACTOR*x
  direction -y
}

What does this do? -and- what plane is my view in?

Wayne

-----------------------------------------

Jim Charter <jrc### [at] msncom> wrote:

> I guess we'll need to see your code and an explanation of what behavior
> seems odd to you in order to help.
>
> If you use an example light source from the insert menu you may notice
> that a technique commonly used is to position the light at the origin
> then add a transform to give its real position.  If you copied a light
> from the insert menu then edited the location maybe you didn't notice
> the further "translate" in the code?


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From: Warp
Subject: Re: Location, Location, Location
Date: 3 Jul 2005 08:55:09
Message: <42c7e02d@news.povray.org>
waynehays1 <way### [at] yahoocom> wrote:
> Maybe I'm slow but I still don't get it.  Are the three numbers x, y, z?  I
> don't think so

  Why you don't think so?

-- 

                                                          - Warp


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From: Kyle
Subject: Re: Location, Location, Location
Date: 3 Jul 2005 09:33:39
Message: <62qfc1h42b4rll8vcb7qg3qhhvsgltau6m@4ax.com>
The numbers are x, y, z.  I'm not sure why you wouldn't think so.

BTW, I just noticed the first link I gave you was for the camera, not
for the light source.  Oops.  Here's the correct link to the
light_source in the manual:

http://www.povray.org/documentation/view/3.6.1/308/


Kyle


On Sat,  2 Jul 2005 23:54:26 EDT, "waynehays1" <way### [at] yahoocom>
wrote:

>Maybe I'm slow but I still don't get it.  Are the three numbers x, y, z?  I
>don't think so, but I cant tell what they are.
>
>Wayne
>
>
>Kyle <hob### [at] gatenet> wrote:
>> You must not have looked in the manual!!!  Look here:
>>
>> http://www.povray.org/documentation/view/3.6.1/246/
>>
>> to get a description of the light_source.  Location is
>> self-explanatory, its a vector describing the location of the
>> light_source.
>>
>> Look here:
>>
>> http://www.povray.org/documentation/view/3.6.1/229/
>>
>> for more info on vectors.  Look here:
>>
>> http://www.povray.org/documentation/view/3.6.1/15/
>>
>> for an explanation of POV-Ray's coordinate system.
>>
>> That should pretty much cover it.
>>
>>
>> Kyle
>>
>>
>> On Sat,  2 Jul 2005 22:41:45 EDT, "waynehays1" <way### [at] yahoocom>
>> wrote:
>>
>> >What do the three numbers for Light Source Location represent?  I have
>> >looked all over for this info, but to no avail.
>> >
>> >Thanks
>> >
>
>
>


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From: Jim Charter
Subject: Re: Location, Location, Location
Date: 3 Jul 2005 09:50:17
Message: <42c7ed19$1@news.povray.org>
waynehays1 wrote:
> I think this is part of what is going on, but it just doesn't tell me what I
> need to know.  I am sure it is here, but I just don't understand.  Thanks
> for being patient with a noob.
> 
> camera {
>   orthographic
>   location <SCALE_FACTOR/2,SCALE_FACTOR,SCALE_FACTOR/2>
>   up SCALE_FACTOR*z
>   right SCALE_FACTOR*x
>   direction -y
> }
> 
> What does this do? -and- what plane is my view in?
> 
Okay, I thought you were talking about light sources.
The meaning of vectors in camera definitions can be a little more
varied.

However the code you show locates the camera in the positive quadrant 
looking straight down at the x-z plane in its positive quadrant.  It is 
apparently designed to view the center of a unit box, lets say, in the 
positive quadrant, and adjust to any scaling of the box
ie.

#local SCALE_FACTOR = 2;


#if ( on )
         camera {
                 orthographic
                 location <SCALE_FACTOR/2, SCALE_FACTOR, SCALE_FACTOR/2>
                 up SCALE_FACTOR*z
                 right SCALE_FACTOR*x
                 direction  -y
         }

#end

box {
         <0,0,0>
         <1,-.1,1>
         scale SCALE_FACTOR
         pigment {
                 gradient x
                 pigment_map {
                         [0 rgb Red]
                         [1 rgb 1] }
                         scale 1
                 }
         finish { ambient 1 }
}


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