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From: Felix Wiemann
Subject: CSG difference with text
Date: 31 Dec 2001 06:40:31
Message: <3c304eaf@news.povray.org>
POV-Ray 3.5 for Windows Beta 9, Intel Pentium 3, 600 MHz, Windows 98


See p.b-t.b !


#include "colors.inc"

camera
   {
   orthographic
   up y * 60
   right x * 80
   location z * -100
   look_at 0
   }

difference
   {
   plane
      {
      -z 0
      pigment{color White}
      finish{ambient 1}
      }
   text
      {
      ttf "signetro" "POV" 0.001 0
      scale 35
      translate <-35, -10, -0.0001>
      pigment{color Red}
      finish{ambient 1}
      }
   }


This creates a text engraved into a plane. (Please note that a plane is
a solid object.) "Signet Roundhand" is a handwriting-like font, so the
letters are big and overlap each other.
But the left part of the letter "P" is cut of. It seems to be a
bounding problem. And where the letters overlap, there are many "noisy
pixels". They were not patterned when I used the perspective camera
instead of the orthographic one.
It occures with the VC++ compile, too.

Felix Wiemann


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From: Thorsten Froehlich
Subject: Re: CSG difference with text
Date: 31 Dec 2001 06:52:39
Message: <3c305187$1@news.povray.org>
In article <3c304eaf@news.povray.org> , "Felix Wiemann" 
<Fel### [at] gmxnet> wrote:

> But the left part of the letter "P" is cut of. It seems to be a
> bounding problem.

You may want to check if the font comes with correct bounds for its
charaters in a font editor.

    Thorsten

____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

Visit POV-Ray on the web: http://mac.povray.org


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From: Francois Labreque
Subject: Re: CSG difference with text
Date: 31 Dec 2001 06:58:58
Message: <3C3050FB.4090606@videotron.ca>
Felix Wiemann wrote:

> This creates a text engraved into a plane. (Please note that a plane is
> a solid object.) "Signet Roundhand" is a handwriting-like font, so the
> letters are big and overlap each other.


> But the left part of the letter "P" is cut of. It seems to be a
> bounding problem.


Confirmed.  And reproducible with "timrom".

> And where the letters overlap, there are many "noisy
> pixels".


Coincident surfaces, maybe?

-- 
/*Francois Labreque*/#local a=x+y;#local b=x+a;#local c=a+b;#macro P(F//
/*    flabreque    */L)polygon{5,F,F+z,L+z,L,F pigment{rgb 9}}#end union
/*        @        */{P(0,a)P(a,b)P(b,c)P(2*a,2*b)P(2*b,b+c)P(b+c,<2,3>)
/*   videotron.ca  */}camera{location<6,1.25,-6>look_at a orthographic}


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From: Felix Wiemann
Subject: Re: CSG difference with text
Date: 31 Dec 2001 07:55:47
Message: <3c306053$1@news.povray.org>
> You may want to check if the font comes with correct bounds for its
> charaters in a font editor.
Where do I find a font editor?


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From: Francois Labreque
Subject: Re: CSG difference with text
Date: 31 Dec 2001 08:05:34
Message: <3C306096.7040705@videotron.ca>
Thorsten Froehlich wrote:

> In article <3c304eaf@news.povray.org> , "Felix Wiemann" 
> <Fel### [at] gmxnet> wrote:
> 
> 
>>But the left part of the letter "P" is cut of. It seems to be a
>>bounding problem.
>>
> 
> You may want to check if the font comes with correct bounds for its
> charaters in a font editor.


As mentioned in my other post, this happens with other fonts as well.  I 
dont think it is dues to the bounding of the font itself as the problem 
is in the Z direction.  Testing with a modified scene shows that the 
problem is that the text isn't "straight".  See image in p.b-t.b.

#include "colors.inc"
camera{
     location < 10, 15, -20 >
     look_at < 10, 0 0 >
     }
plane{
     y, 0
     pigment{ White }
     }
union{
     box{
         < -5, -1, 0 > < 25, 20, 20 >
         pigment{ Gray50 }
         }
     text{
         ttf "timrom" "POV" 0.1 0
         scale < 10, 10, 100000 >
         pigment{ Red }
         }
     }
light_source{
     < -15, 50, -15 >
     White
     }



-- 
/*Francois Labreque*/#local a=x+y;#local b=x+a;#local c=a+b;#macro P(F//
/*    flabreque    */L)polygon{5,F,F+z,L+z,L,F pigment{rgb 9}}#end union
/*        @        */{P(0,a)P(a,b)P(b,c)P(2*a,2*b)P(2*b,b+c)P(b+c,<2,3>)
/*   videotron.ca  */}camera{location<6,1.25,-6>look_at a orthographic}


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From:
Subject: Re: CSG difference with text
Date: 31 Dec 2001 08:05:45
Message: <eio03uokue1l26619dm4c2rd5bhskckpfb@4ax.com>
On Mon, 31 Dec 2001 13:58:31 +0100, "Felix Wiemann"
<Fel### [at] gmxnet> wrote:
> Where do I find a font editor?

Perhaps something at http://www.tucows.com/mmedia/fonttool95.html ?

ABX
--
#declare _=function(a,b,x){((a^2)+(b^2))^.5-x}#default {pigment{color rgb 1}}
union{plane{y,-3}plane{-x,-3}finish{reflection 1 ambient 0}}isosurface{ //ABX
function{_(x-2,y,1)&_((x+y)*.7,z,.1)&_((x+y+2)*.7,z,.1)&_(x/2+y*.8+1.5,z,.1)}
contained_by{box{<0,-3,-.1>,<3,0,.1>}}translate z*15finish{ambient 1}}//POV35


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From: Felix Wiemann
Subject: Re: CSG difference with text
Date: 31 Dec 2001 08:11:59
Message: <3c30641f@news.povray.org>
> > And where the letters overlap, there are many "noisy
> > pixels".
> Coincident surfaces, maybe?
Yes, I think so, too, but a difference with two overlapping boxes *with
coincident surfaces* instead of the text creates in the overlapping
area only black.


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From: Mike Williams
Subject: Re: CSG difference with text
Date: 31 Dec 2001 15:36:48
Message: <NXokKHAYwMM8EwpN@econym.demon.co.uk>
Wasn't it Felix Wiemann who wrote:
>This creates a text engraved into a plane. (Please note that a plane is
>a solid object.) "Signet Roundhand" is a handwriting-like font, so the
>letters are big and overlap each other.
>But the left part of the letter "P" is cut of. It seems to be a
>bounding problem. And where the letters overlap, there are many "noisy
>pixels". They were not patterned when I used the perspective camera
>instead of the orthographic one.
>It occures with the VC++ compile, too.

There are two different things going on here

(1) The top left corner of the "P" is cut off.

This is confirmed with other fonts, and appears to be caused by the text
being rotated by about <0.001,0.001,0>. In the first example scene, this
tiny rotation is enough to cause one corner to submerge below the plane
that's only 0.0001 pov-units away. In the second example scene the
effect of the rotation is amplified by the 100000 fold scaling in the z
direction. POV 3.1 exhibits the same effect.

(2) Patterning where the letters overlap.

I assume that the overlap is deliberate in the Signet Roundhand font,
which I don't have. I don't have any fonts where the letters are
intended to overlap. However, if I make two letters in Times Roman as
two separate text objects and overlap them (with or without
"orthographic") exactly the same sort of patterning occurs. I reckon
this is just ordinary coincident surface artefacts, and not a bug.

-- 
Mike Williams
Gentleman of Leisure


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From: Felix Wiemann
Subject: Re: CSG difference with text
Date: 1 Jan 2002 14:16:23
Message: <3c320b07$1@news.povray.org>
"Mike Williams" <mik### [at] nospamplease> schrieb im Newsbeitrag
news:NXo### [at] econymdemoncouk...
> I assume that the overlap is deliberate in the Signet Roundhand font,
> which I don't have. I don't have any fonts where the letters are
> intended to overlap. However, if I make two letters in Times Roman as
> two separate text objects and overlap them (with or without
> "orthographic") exactly the same sort of patterning occurs. I reckon
> this is just ordinary coincident surface artefacts, and not a bug.
I've just used such a font in a clock-scene. There are initials
engraved into the clock. Even I don't understand why coincident
surfaces create such artefacts with a CSG difference, I think it is a
bug, because the text object should be *one* object and not many single
objects.


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From: Thorsten Froehlich
Subject: Re: CSG difference with text
Date: 1 Jan 2002 14:28:18
Message: <3c320dd2@news.povray.org>
In article <3c320b07$1@news.povray.org> , "Felix Wiemann" 
<Fel### [at] gmxnet> wrote:

> text object should be *one* object and not many single
> objects.

A text object is many single characters.  Of course one could change it to
some extend at the serve penalty of *much* slower rendering.  Expect the
render speed would be lower by a factor of n, where n is the number of
characters in the text object.  I am not sure this is really what you
want...

    Thorsten

____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

Visit POV-Ray on the web: http://mac.povray.org


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