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From: Thorsten Froehlich
Subject: Re: Function image type mirrored vertically
Date: 7 Apr 2002 05:17:23
Message: <3cb00ea3@news.povray.org>
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In article <3caf823a@news.povray.org> , "Rune" <run### [at] mobilixnet dk>
wrote:
> Right, then one coordinate system is reversed vertically compared to the
> other. Why do you say it isn't reversed when obviously everyone can see that
> it is indeed reversed, no matter what you choose to call it?
It isn't reversed. It is in exactly in the same coordinate system as in all
other images!
>> When generating the image the origin and coordiante
>> system of an image is used. This means that the
>> upper left is (0,0) and the lower right of the image
>> generated is function value (1,1).
>
> Yet, strangely, when using an image map the upper left corner is at (0,1)
> and the lower right corner is at (1,0). This is because POV-Ray takes care
> of the correction for the user.
>
> Why can't POV-Ray correct the alignment for the user when using the function
> image type, so that the user won't see any hint of reversed coordinates?
It is correct just like for all other image map types. As I pointed out, try
to substitute the function image by a plain image map. You will notice that
the origin of the image is of course still at (0,0) in image coordinates,
which equals (0,1,0) in POV-Ray coordinates. The function is also at exactly
this place, (0,0) in image coordinates and (0,1,0) in POV-Ray coordinates.
So you generate an image using a function inside the image coordinate system,
which goes from (0,0) to (1,1) where (0,0) is defined as the upper left and
(1,1) as the lower right. The (0,0) is then mapped to (0,1,0) and the (1,1)
is mapped to (1,0,0) like for all other image formats.
Thorsten
____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde
Visit POV-Ray on the web: http://mac.povray.org
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"Thorsten Froehlich" wrote:
> It isn't reversed. It is in exactly in the same
> coordinate system as in all other images!
Please see my other reply to you in this thread where I have better
explained my point.
Rune
--
3D images and anims, include files, tutorials and more:
Rune's World: http://rsj.mobilixnet.dk (updated Mar 19)
POV-Ray Users: http://rsj.mobilixnet.dk/povrayusers/
POV-Ray Ring: http://webring.povray.co.uk
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It will be interesting to see how many more of these Rune vs. Thorsten
fights will we see before the final release... ;)
--
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -
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"Warp" wrote:
> It will be interesting to see how many more of these
> Rune vs. Thorsten fights will we see before the final
> release... ;)
I consider a discussion to be an attempt at obtaining mutual understanding.
I don't care if Thorsten convinces me or I convince him, I just don't like
when one part quit the discussion before mutual understanding has been
reached...
Rune
--
3D images and anims, include files, tutorials and more:
Rune's World: http://rsj.mobilixnet.dk (updated Mar 19)
POV-Ray Users: http://rsj.mobilixnet.dk/povrayusers/
POV-Ray Ring: http://webring.povray.co.uk
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Rune <run### [at] mobilixnetdk> wrote:
> I consider a discussion to be an attempt at obtaining mutual understanding.
> I don't care if Thorsten convinces me or I convince him, I just don't like
> when one part quit the discussion before mutual understanding has been
> reached...
Sometimes just stopping is the only solution if the other one just refuses
or is incapable of understanding.
--
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -
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"Warp" wrote:
> Sometimes just stopping is the only solution if the
> other one just refuses or is incapable of understanding.
But I don't think Thorsten is incapable of understanding... ;)
Seriously, I don't think Thorsten have responded to my argument yet, so I
think it would be fair to keep the discussion running as long as we keep
getting closer to mutual understanding, as I think we are.
Rune
--
3D images and anims, include files, tutorials and more:
Rune's World: http://rsj.mobilixnet.dk (updated Mar 19)
POV-Ray Users: http://rsj.mobilixnet.dk/povrayusers/
POV-Ray Ring: http://webring.povray.co.uk
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On Sat, 6 Apr 2002 00:23:15 +0200, "Rune" <run### [at] mobilixnetdk> wrote:
> The function image type is mirrored vertically.
As I understand all those discussion (with my poor language):
When function 100, 100 {...} is performed it means that engine samples space
from <0,0,0> to <1,1,0> and makes grid of values. After sampling it isn't
coordinate system at all. It is internally flat grid/array[100][100] of values
just like grid with values of pixels/colors in images. Then it is passed to the
same procedure as typical image. This is separated procedure and it doesn't
metter what grid is. Grid is a grid, it is placed/mapped from <0,1,0> to <1,0,0>
becouse general rule for images is that first line of grid makes top line of
image. Right ?
ABX
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On Sun, 07 Apr 2002 18:50:23 +0200, "Thorsten Froehlich" <tho### [at] trfde>
wrote:
> No, a real image is generated internally, there is no special traetment for
> function images at all.
so, at parse time internal grid (as image) is generated by sampling content of
function, and rest about mapping rules is right in my post ?
ABX
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From: Thorsten Froehlich
Subject: Re: Function image type mirrored vertically
Date: 7 Apr 2002 13:12:08
Message: <3cb07de8$1@news.povray.org>
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Skiba <abx### [at] babilonorg> wrote:
> and rest about mapping rules is right in my post ?
Yes.
Thorsten
____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde
Visit POV-Ray on the web: http://mac.povray.org
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"Thorsten Froehlich" wrote:
> W"odzimierz ABX Skiba wrote:
> > and rest about mapping rules is right in my post ?
>
> Yes.
The problem is that POV-Ray assumes the pattern function to have the origin
in the upper left corner like all the other image types, when in fact
patterns have the origin in the lower left corner *unlike* all the other
image types. So just because all the other image types are reversed, it
doesn't mean that the function image type should be too. Thorsten, I haven't
yet heard your argument against this.
In POV-Ray x is defined as right and y is defined as up. Thus, when
considering the square from <0,0,0> to <1,1,0>, which is the square POV-Ray
use for the pattern image type, the origin is in the lower left corner, not
the upper left corner. If you refuse to change the feature, could you please
explain why?
Rune
--
3D images and anims, include files, tutorials and more:
Rune's World: http://rsj.mobilixnet.dk (updated Mar 19)
POV-Ray Users: http://rsj.mobilixnet.dk/povrayusers/
POV-Ray Ring: http://webring.povray.co.uk
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