This is mainly for Chris but anyone else playing with glows may
want to take note.

I've been working on a scene with glows and I've encountered a problem

Glows do not behave well when #declared.

The following gives an error.

#declare Test=
 glow {
  location <0,0,0>
  color rgb <1,0,0>
 }

while

#declare Test =
 union {
  glow {
   location <0,0,0>
   color rgb <1,0,0>
  }
  sphere {
   <0,0,0>,1
   pigment {rgb 1}
  }
 }

gives a warning that there should be at least 2 objects in a CSG
and places the glow in the scene.

A subsequent call
object {Test}
simply places the sphere into the scene.

Also pov-ray returns an error if a glow is the last thing in a scene.

Chris, are these issues going to be addressed in the next version?

Gail
********************************************************************
* gsh### [at] monotixcoza              * System.dat not found.         *
* http://www.rucus.ru.ac.za/~gail/ * Reformat hard drive Y)es O)k  *
********************************************************************
* If at first you don't succeed, call it version 1.0               *
********************************************************************

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Gail Shaw <gsh### [at] monotixcoza> wrote:

> This is mainly for Chris but anyone else playing with glows may
> want to take note.
> 
> I've been working on a scene with glows and I've encountered a problem
> 
> Glows do not behave well when #declared.
> 
> The following gives an error.
[...]
We just discovered that while testing the patch. We will take a look at
it, but Chris, if you find a solution before us: Please send it over!
Thanks.
> 
> gives a warning that there should be at least 2 objects in a CSG
> and places the glow in the scene.
> 
> A subsequent call
> object {Test}
> simply places the sphere into the scene.
> 
> Also pov-ray returns an error if a glow is the last thing in a scene.
We fixed that one for MegaPov 0.6. A small fix is still needed for a
simular problem.
 
Smellenbergh

> Chris, are these issues going to be addressed in the next version?
> 
> Gail
> ********************************************************************
> * gsh### [at] monotixcoza              * System.dat not found.         *
> * http://www.rucus.ru.ac.za/~gail/ * Reformat hard drive Y)es O)k  *
> ********************************************************************
> * If at first you don't succeed, call it version 1.0               *
> ********************************************************************


-- 
e-mail:sme### [at] skynetbe

http://users.skynet.be/smellenbergh

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In article <39d1b98d@news.povray.org>, "Gail Shaw" 
<gsh### [at] monotixcoza> wrote:

> I've been working on a scene with glows and I've encountered a problem
> 
> Glows do not behave well when #declared.

Not surprising, since I haven't put code in to allow declaring them...on 
the to-do list.


> gives a warning that there should be at least 2 objects in a CSG
> and places the glow in the scene.
> 
> A subsequent call
> object {Test}
> simply places the sphere into the scene.

That is simply because glows are not objects and do not behave 
completely like objects yet. Another item on the to-do list.


> Also pov-ray returns an error if a glow is the last thing in a scene.

That is odd...

-- 
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/

<><

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In article <1ehmqh4.c2356i1u7rkttN%smellenbergh@skynet.be>, 
sme### [at] skynetbe (smellenbergh) wrote:

> We just discovered that while testing the patch. We will take a look at
> it, but Chris, if you find a solution before us: Please send it over!

I will try to figure out how to implement this...


> We fixed that one for MegaPov 0.6. A small fix is still needed for a
> simular problem.

What was the problem?

-- 
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/

<><

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Another item on the to-do list.

Good to know. I really like glows.

>
> > Also pov-ray returns an error if a glow is the last thing in a scene.
>
> That is odd...

I tried the following as a test scene:

// start ********************************
camera {
 location <0,0,-5>
 look_at <0,0,0>
}

glow {
  location <0,0,0>
  color rgb <0.8,0.6,0>*2.5
  type 1
 }
// End****************************

and I got the following message:

--------------------------------------------------
  All Streams to console..........On
  Debug Stream to console.........On
  Fatal Stream to console.........On
  Render Stream to console........On
  Statistics Stream to console....On
  Warning Stream to console.......On

  type 1
 }

 <----ERROR

C:\My Documents\test.pov:10: error: object or directive expected but End of
File found instead.


Returned from renderer (non-zero return value)

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

If I put any object after the glow then the scene renders.

Gail
********************************************************************
* gsh### [at] monotixcoza              * System.dat not found.         *
* http://www.rucus.ru.ac.za/~gail/ * Reformat hard drive Y)es O)k  *
********************************************************************
* If at first you don't succeed, call it version 1.0               *
********************************************************************

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> > We fixed that one for MegaPov 0.6. A small fix is still needed for a
> > simular problem.
> 
> What was the problem?
First of all, in parse.c in function Parse() change things like this
(and this is for that last little fix mentioned):

  Parse_Frame ();

  Post_Media(Frame.Atmosphere);

#ifdef GlowPatch
  if (Frame.Objects == NULL && Frame.Glows == NULL)
  {
    Error ("No objects or glows in scene.");
  }
#else
  if (Frame.Objects == NULL)
  {
    Error ("No objects in scene.");
  }
#endif
  Stage = STAGE_CLEANUP_PARSE;

This makes it possible to render a scene with no objects, no lights but
only glows.
To allow parsing you should modify Parse_Frame() in parse.c like this
(at the end of the function):

#ifdef GlowPatch
  /*YS sept 18 2000 
     added this here too to allow 
    for a scene with only glow */
  CASE(GLOW_TOKEN)
    #ifdef UnofficialBlocking
        parseUnofficialFeature(60);
    #endif  
    {
    GLOW * NewGlow = Create_Glow();
    Parse_Glow(NewGlow);
    Add_Glow(NewGlow);
  }
  END_CASE
#endif

     OTHERWISE
       UNGET
       Object = Parse_Object();
       if (Object == NULL)
         Parse_Error_Str ("object or directive");
       Post_Process (Object, NULL);
       Link_To_Frame (Object);
     END_CASE
   END_EXPECT
  }


Smellenbergh

-- 
e-mail:sme### [at] skynetbe

http://users.skynet.be/smellenbergh

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smellenbergh wrote:
> 
> This makes it possible to render a scene with no objects, no lights but
> only glows.

Why not simply allowing POV-Ray to render even if there are no
objects ?  Issuing a simple warning instead of an error...

Fabien.

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Or making povray consider a glow to be an object.

  If there are lots of glows in the scene, wouldn't they benefit from
bounding objects (perhaps spheres could be the best)?

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):_;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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In article <39d4843d@news.povray.org>, Warp <war### [at] tagpovrayorg> 
wrote:

>   Or making povray consider a glow to be an object.

That is my goal...to make them imitate objects, like light_sources do. 
Of course, things like "hollow" and "open" would be meaningless to 
them...but they will eventually be useable in CSG's and variables.


>   If there are lots of glows in the scene, wouldn't they benefit from
> bounding objects (perhaps spheres could be the best)?

No more than plane objects or sky_spheres would...the "realistic" glow 
types are "infinite". They are not objects, but effects which depend on 
the angle and proximity of the ray to a point, which makes bounding a 
bit...tricky. However, my most recent version does include a "radius" 
feature which allows you to cut off calculation beyond a certain 
distance. But this can often make a large difference in the output, 
especially when using large numbers of glows, and isn't useful as an 
optimization technique for small numbers.

-- 
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/

<><

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