I didn't see any message about this previously. I am running Win98
512 Mb on an Athelon XP 2500+. I retrieved this program from the
net. It is credited to Greg M. Johnson 2001. It runs fine on 3.5,
however I get an unhandled exception in PoV 3.6.1.

The code is short, and uses an array of 7500 objects.

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Here is the code:

// Demo scene for povray 3.5
// Features Gaussian distribution and use of trace function
// Composed by Greg M. Johnson 2001
// Uses a macro by Rico Reusser.
//

#declare UseRadiosity = no;
#declare S = seed(20173);
#declare CompRadius=0.05;//radius of blob components;
#declare CompNum=7500;//number of blob components

#include "colors.inc"
#if(UseRadiosity)
 global_settings {
  radiosity {
   pretrace_start 0.04
   pretrace_end 2/300
   count 400
   recursion_limit 2
   nearest_count 1
   error_bound 0.2
  }
 }

 #default {finish { ambient 0}}
#else
 light_source {<0, 200, -100> colour rgb 1.5}
#end


//This macro created by Rico Reusser <reu### [at] chorusnet>
#declare e = 2.718281828459;
#macro Gauss(RSR)
 sqrt(-2*log(rand(RSR))/log(e))*cos(2*pi*rand(RSR))
#end


plane {y,-0.9105  pigment {White}}


#declare Norm=<0,0,0>;//This variable is used to hold the normal vector
obtained
//using trace(). This vector is then used to determine whether an
intersection was found.
#declare Posy=array[CompNum]
#declare Posy[0]=<Gauss(S),0,Gauss(S)>;
#declare Ally=sphere {Posy[0], CompRadius}//This variable will hold a
collection of spheres,
//one for each blob component. The algorithm checks against this object to
decide
//if a component is "on top of" another.

#declare N=1;
#while(N<CompNum)
 #declare Test=<Gauss(S),0,Gauss(S)>;
 #declare Tracey=trace(Ally,Test+100*y,-y,Norm);

 #if (Norm.x = 0 & Norm.y = 0 & Norm.z = 0)
  #declare Posy[N]=Test;
  //put the new component at y=0
 #else
  #declare Posy[N]=Tracey+Norm*CompRadius;
  //put the new component at a point "above" the one it hit
  //The algorithm actually uses the normal to compute the position
 #end

 //Add new sphere to union
 #declare Ally=
 union {object {Ally}
  sphere {Posy[N], CompRadius}
 }

// #debug concat(str(N,4,0), "n")
 #declare N=N+1;
#end

blob {
 threshold 0.5

 #declare N=0;
 #while(N<CompNum)
  sphere {Posy[N], CompRadius*2.85, 1}
  #declare N=N+1;
 #end
 pigment {rgb <0.2,1,0.1>}
}


background {White}

sphere {<0.5,0,0>, 0.5
 inverse
 pigment {
  gradient x
  pigment_map {
   [0.0   rgb 0]
   [0.995   rgb 0.04]
   [1.0   rgb 2]
  }
 }
 finish {ambient 20}
 translate <-0.5,0,0>
 scale 500
}

camera {
 location <0,3,-15>
 look_at <0,0,0>
 angle 20
}

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In article <web.418baf5b1de09dac8b9853a0@news.povray.org> , "Dan" 
<dco### [at] sympaticoca> wrote:

> I didn't see any message about this previously. I am running Win98
> 512 Mb on an Athelon XP 2500+. I retrieved this program from the
> net. It is credited to Greg M. Johnson 2001. It runs fine on 3.5,
> however I get an unhandled exception in PoV 3.6.1.

The scene design was and is defective.  We just forgot to remove it from the
distribution.

    Thorsten

____________________________________________________
Thorsten Froehlich
e-mail: mac### [at] povrayorg

I am a member of the POV-Ray Team.
Visit POV-Ray on the web: http://mac.povray.org

Post a reply to this message

"Thorsten Froehlich" <tho### [at] trfde> wrote:
>
> The scene design was and is defective.  We just forgot to remove it from the
> distribution.
>
>     Thorsten
>
> ____________________________________________________
> Thorsten Froehlich
> e-mail: mac### [at] povrayorg
>
> I am a member of the POV-Ray Team.
> Visit POV-Ray on the web: http://mac.povray.org

Thank you for your official response. Though I don't understand
what is wrong in the scene design, I think that this should
be listed as a bug. Any sequence of code that causes the program
to crash is bad. The fact that it works without problems in 3.5
just makes it more likely that the bug will be encountered.

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In article <web.4198bceb330fe60dc8b9853a0@news.povray.org> , "Dan" 
<dco### [at] sympaticoca> wrote:

> Thank you for your official response. Though I don't understand
> what is wrong in the scene design, I think that this should
> be listed as a bug. Any sequence of code that causes the program
> to crash is bad. The fact that it works without problems in 3.5
> just makes it more likely that the bug will be encountered.

No, it is not a bug in POV-Ray and that is does not occur on some platforms
when using POV-Ray 3.5 is pure luck.

    Thorsten

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

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

Post a reply to this message

Dan wrote:
> 
> Any sequence of code that causes the program
> to crash is bad.

That is right but it is quite illusive to assume it would be possible to 
prevent POV-Ray from crashing with *any* piece of code.  So obviously 
this kind of problem has low priority in comparison to problems that 
cause something failing that should work.

BTW it is well possible to modify this scene to work as intended but 
there is no really efficient way to do this kind of thing in current SDL.

Christoph

-- 
POV-Ray tutorials, include files, Sim-POV,
HCR-Edit and more: http://www.tu-bs.de/~y0013390/
Last updated 23 Sep. 2004 _____./\/^>_*_<^\/\.______

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Thorsten Froehlich wrote:
> No, it is not a bug in POV-Ray and that is does not occur on some platforms
> when using POV-Ray 3.5 is pure luck.

Luck has nothing to do with the execution of computer code.  There must 
be another reason why it does not happen on some platforms in version 3.5.

-- 
Tim Cook
http://home.bellsouth.net/p/PWP-empyrean

-----BEGIN GEEK CODE BLOCK-----
Version: 3.12
GFA dpu- s: a?-- C++(++++) U P? L E--- W++(+++)>$
N++ o? K- w(+) O? M-(--) V? PS+(+++) PE(--) Y(--)
PGP-(--) t* 5++>+++++ X+ R* tv+ b++(+++) DI
D++(---) G(++) e*>++ h+ !r--- !y--
------END GEEK CODE BLOCK------

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In article <4198cda3@news.povray.org> , Tim Cook <z99### [at] bellsouthnet>  
wrote:

>> No, it is not a bug in POV-Ray and that is does not occur on some platforms
>> when using POV-Ray 3.5 is pure luck.
>
> Luck has nothing to do with the execution of computer code.  There must
> be another reason why it does not happen on some platforms in version 3.5.

No, but this is not povray.programming .

    Thorsten

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

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

Post a reply to this message