Le Forgeron wrote:
> 
> Massimo Valentini wrote:

> 
> > If someone has time and inclination to check what I did, I'll appreciate
> > and, as always, hints, comments and counter examples are welcome.
> 
> I have some time on this weekend, so I will have a look at it.
> (My current suggestion for correction is to remove the optimisation,
> which is really inappropriate if you are correct).
> More on monday...


No need to wait that long.
It's ok with all the bogus blob scene I had.

With the correction, it's faster for rendering than removing the optimisation, and 
there is far less need for sturm (which allow to keep more speed too!!!).

I would suggest that the correction be incorporated in the official code.

-- 
Non Sine Numine
http://grimbert.cjb.net/
Etiquette is for those with no breeding;
fashion for those with no taste.

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> I think to have found a little error in the file blob.cpp


Wow, this is a complicated post. While I may be able to understand it if I
slowly read all the way through it, would you care to give a simplified
explanation of what was wrong in the code? Was it just a typo? Was something
assumed to work that didn't? Just out of curiosity.

And was this the only bug in the blob code? That'd be nice if it were =)

 - Slime
[ http://www.slimeland.com/ ]

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"Slime" ha scritto 
: > I think to have found a little error in the file blob.cpp
: 
: 
: Wow, this is a complicated post. While I may be able to understand it if I
: slowly read all the way through it, would you care to give a simplified
: explanation of what was wrong in the code? Was it just a typo? Was something
: assumed to work that didn't? Just out of curiosity.

You may call it a typo. I think someone trying to simplify a computation
(division -> multiplication of the reciprocal or similar) made a double
division instead of a division and a multiplication, so three numbers 
ended up to be a fourth of their correct value.

The lines to modify are around 545 in the file blob.cpp (if you need more 
context, look at my previous post or the bug report). 
Substitute for example:

dk[2] = newcoeffs[4] + 0.50 * (newcoeffs[3] + newcoeffs[2] / 12.0);
dk[3] = newcoeffs[4] + 0.50 * (0.375 * newcoeffs[3] + newcoeffs[2] + 0.125 *
newcoeffs[1]);

with:

dk[2] = newcoeffs[4] + 0.50 * (newcoeffs[3] + newcoeffs[2] / 3.0);
dk[3] = newcoeffs[4] + 0.50 * (1.5 * newcoeffs[3] + newcoeffs[2] + 0.5 *
newcoeffs[1]);


: And was this the only bug in the blob code? That'd be nice if it were =)
: 

It is the only one I found. But it does not affect other scenes 
reported as bugs.

Massimo

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Massimo Valentini wrote:

> "Slime" ha scritto 

> 
> : And was this the only bug in the blob code? That'd be nice if it were =)
> : 
> 
> It is the only one I found. But it does not affect other scenes 
> reported as bugs.


Well, it might not correct the Media & Blob (I did not test that), but 
at least, it perfectly corrects the cuts that have been present in blob 
since a long time (and that started job 189 during the release-beta 
periode).
Moreover, your correction is mathematically explained and make sense.

I'm just wondering if any people of the Pov-team reads this newsgroup 
(and will take the solution from here) or if you need to make a formal 
posting somewhere else (p.bugreport is moderated, but now that you have 
discussed here, the moderator should agree to a post... otherwise, I'm 
afraid of a post in p.general, just to get the attention of the Pov-team 
members...)

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Le Forgeron wrote:

> I'm just wondering if any people of the Pov-team reads this newsgroup
> (and will take the solution from here) or if you need to make a formal
> posting somewhere else (p.bugreport is moderated, but now that you have
> discussed here, the moderator should agree to a post... otherwise, I'm
> afraid of a post in p.general, just to get the attention of the Pov-team
> members...)

I will check into this.

-- 
Ken Tyler

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In article <3DB### [at] freefr> , Le Forgeron <jgr### [at] freefr>  
wrote:

> I'm just wondering if any people of the Pov-team reads this newsgroup
> (and will take the solution from here) or if you need to make a formal
> posting somewhere else (p.bugreport is moderated, but now that you have
> discussed here, the moderator should agree to a post... otherwise, I'm
> afraid of a post in p.general, just to get the attention of the Pov-team
> members...)

No patch has been posted.  Just a few code examples.  It isn't possible to
say much from just a few formulas.

    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:

> In article <3DB### [at] freefr> , Le Forgeron <jgr### [at] freefr>  
> wrote:
> 
> 
>>I'm just wondering if any people of the Pov-team reads this newsgroup
>>(and will take the solution from here) or if you need to make a formal
>>posting somewhere else (p.bugreport is moderated, but now that you have
>>discussed here, the moderator should agree to a post... otherwise, I'm
>>afraid of a post in p.general, just to get the attention of the Pov-team
>>members...)
>>
> 
> No patch has been posted.  Just a few code examples.  It isn't possible to
> say much from just a few formulas.
> 


I hope Massimo Valentini will be ok with the following...

Here your requested patch:
      http://jgrimbert.free.fr/pov/correct/blob.pat

I only made it for 3.1, but it should apply fine to 3.5 too!
(once you give the blob.cpp filename to patch when it complains about 
not founding blob.c )

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In article <3DC### [at] freefr> , Le Forgeron <jgr### [at] freefr>  
wrote:

> I hope Massimo Valentini will be ok with the following...

Thanks, the diff format, while not ideal, at least makes clear what changed.

    Thorsten

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

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

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On Thu, 31 Oct 2002 21:15:02 +0100, Thorsten Froehlich <tho### [at] trfde> wrote:
> In article <3DC### [at] freefr> , Le Forgeron <jgr### [at] freefr>  
> wrote:
> 
>> I hope Massimo Valentini will be ok with the following...
> 
> Thanks, the diff format, while not ideal, at least makes clear
> what changed.

what would be ideal?

-- 
Safari - y7p### [at] sneakemailcom
"Talk is cheap. Show me the code." - Linus Torvalds

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In article <slr### [at] safarihomelinuxnet> , Safari 
<y7p### [at] sneakemailcom>  wrote:

>> Thanks, the diff format, while not ideal, at least makes clear
>> what changed.
>
> what would be ideal?

The full file, at least if there are multiple changes, is usually easier to
integrate.  It happens that the codebase I work on differs from the current
public codebase a lot.  Fortunately not the blob code...  :-)

    Thorsten

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

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

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