plib-devel

Re: [Plib-devel] How many triangles in a leaf?

[John F. F. <joh...@cy...>]

OK, do we do this before or after the release?  I give you three datapoints:

(1)  I am not a project admin on PLIB, so I can't do any PLIB release work.

(2)  The October 1 deadline is about a week away and there hasn't been any motion towards a release yet.

(3)  A bird in the hand is worth two in the bush.

Therefore I would suggest that we put the change in now.

	- John


-----Original Message-----
From:	Wolfram Kuss 
Sent:	Saturday, September 22, 2007 3:02 PM
To:	PLIB Developers
Subject:	Re: [Plib-devel] How many triangles in a leaf?

I agree we should increase the limit.
The argument that this will encourage bad models is only half true
IMHO as often I have to work with finished models and am not even in
contact with the modeller. 

I am using "unsigned short" instead of "short" for a long time now
(probably 2 years or so) without issues. Going to unsigned int would
probably be a bit more work, but would be welcome by me.

Bye bye,
Wolfram.

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Re: [Plib-devel] How many triangles in a leaf?

[John F. F. <joh...@cy...>]

If somebody can send me some patches I can put them into the code.  I have 
re-read Paolo's post and the responses and I do not want to make such a 
subtle change to a library that I do not know well.

	- John


-----Original Message-----
From:	Wolfram Kuss
Sent:	Saturday, September 22, 2007 3:02 PM
To:	PLIB Developers
Subject:	Re: [Plib-devel] How many triangles in a leaf?

I agree we should increase the limit.
The argument that this will encourage bad models is only half true
IMHO as often I have to work with finished models and am not even in
contact with the modeller.

I am using "unsigned short" instead of "short" for a long time now
(probably 2 years or so) without issues. Going to unsigned int would
probably be a bit more work, but would be welcome by me.

Bye bye,
Wolfram.

-------------------------------------------------------------------------
This SF.net email is sponsored by: Microsoft
Defy all challenges. Microsoft(R) Visual Studio 2005.
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Re: [Plib-devel] How many triangles in a leaf?

[Steve B. <st...@sj...>]

I would strongly advise against this change.  Sending 32 bit indices 
instead of 16 is a big penalty on reasonably size meshes.  It's not
hard to split big meshes into 65536 vertex chunks and it's a bad idea
to slow the package down for reasonably sized models just in order to
support the clueless.

John F. Fay wrote:
> If somebody can send me some patches I can put them into the code.  I have 
> re-read Paolo's post and the responses and I do not want to make such a 
> subtle change to a library that I do not know well.
> 
> 	- John
> 
> 
> -----Original Message-----
> From:	Wolfram Kuss
> Sent:	Saturday, September 22, 2007 3:02 PM
> To:	PLIB Developers
> Subject:	Re: [Plib-devel] How many triangles in a leaf?
> 
> I agree we should increase the limit.
> The argument that this will encourage bad models is only half true
> IMHO as often I have to work with finished models and am not even in
> contact with the modeller.
> 
> I am using "unsigned short" instead of "short" for a long time now
> (probably 2 years or so) without issues. Going to unsigned int would
> probably be a bit more work, but would be welcome by me.
> 
> Bye bye,
> Wolfram.
> 
> -------------------------------------------------------------------------
> This SF.net email is sponsored by: Microsoft
> Defy all challenges. Microsoft(R) Visual Studio 2005.
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> _______________________________________________
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> 
> 
> 
> 
> 
> 
> -------------------------------------------------------------------------
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Re: [Plib-devel] How many triangles in a leaf?

[Wolfram K. <w_...@rz...>]

I agree we should not force a slowdown on people.

So I suggest:
Let's not hold up the release on this.

I have not looked at the 16 to 32 bit change, but it may well be
possible to use a typedef or define so one change to the source
switches. I am very sure I have done this for the short to unsigned
short change.=20

Lets look at the 16 to 32 bit change. If fairly easily possible, and
if we can make it optional, let's do that. If not, let's at least do
the optional short to unsigned short change.=20


Bye bye,
Wolfram.

[Plib-devel] R: How many triangles in a leaf?

[Paolo L. <p.l...@ci...>]

> -----Messaggio originale-----
> Da: pli...@li... 
> [mailto:pli...@li...] Per conto 
> di Steve Baker
> Inviato: domenica 23 settembre 2007 21.57
> A: joh...@cy...; PLIB Developers
> Oggetto: Re: [Plib-devel] How many triangles in a leaf?
> 
> I would strongly advise against this change.  Sending 32 bit 
> indices instead of 16 is a big penalty on reasonably size 
> meshes.  It's not hard to split big meshes into 65536 vertex 
> chunks and it's a bad idea to slow the package down for 
> reasonably sized models just in order to support the clueless.

I never thought to move all indices to 32 bit, and to support 2^32 vertices
per mesh.

Today the following limits hold for a ssgVtxArray:

- max number of vertices: sizeof(unsigned int) (a ssgVertexArray is a
ssgSimpleList)
- max number of indices: sizeof(unsigned int) (a ssgIndexArray is a
ssgSimpleList)
- max vertex index: sizeof(short) (indices are actually stored as shorts in
a ssgIndexArray)

Here's the mother of all inconsistencies: we can have up to 2^32 vertices,
but can address only the first 32768. So by loaders' point of view, it's not
important to have a limit, whatever it be, it's important to enforce the
respect of such a limit at ssgVtxArray creation. I don't know each loader
compliance to that, I took care of it only recently in the 3DS loader by
splitting larger meshes in sizeof(short)/3 (10922) triangles (triangle n has
indices n*3, n*3+1, n*3+2) (this is already in the SVN version of the 3DS
loader). Other loaders could make a more smarter use of the 32K-limited
indices so to address many more triangles than the 3DS one.

So it's solution time now:

a. cleanness: move to unsigned short indices, and limit the number of
vertices to that size - we would thus stay still within the 16-bit indices
so performances wouldn't suffer;

b. freedom: move to unsigned int indices, leave ssgVertexArray as it is
(since it is already unsigned int-capable) - virtually no mesh split longer
needed, performances would probably suffer a bit;

c. future: don't do anything now, let's wait to redesign the leaf geometry
storing from scratch in a possible Plib 2.0 version, where we could
parametrize several aspects of a ssgVtxArray, including whether to go to
Vertex arrays, VBOs, or possible newer, more performant OGL mechanisms.

As far as we are all aware of such intrinsic subtle limitation, I'm not in a
hurry to anything could compromise performances or Plib instability.
Wolfram, thanks for your agreeableness.

Greetings -

Paolo Leoncini


> John F. Fay wrote:
> > If somebody can send me some patches I can put them into 
> the code.  I 
> > have re-read Paolo's post and the responses and I do not 
> want to make 
> > such a subtle change to a library that I do not know well.
> > 
> > 	- John
> > 
> > 
> > -----Original Message-----
> > From:	Wolfram Kuss
> > Sent:	Saturday, September 22, 2007 3:02 PM
> > To:	PLIB Developers
> > Subject:	Re: [Plib-devel] How many triangles in a leaf?
> > 
> > I agree we should increase the limit.
> > The argument that this will encourage bad models is only half true 
> > IMHO as often I have to work with finished models and am 
> not even in 
> > contact with the modeller.
> > 
> > I am using "unsigned short" instead of "short" for a long time now 
> > (probably 2 years or so) without issues. Going to unsigned 
> int would 
> > probably be a bit more work, but would be welcome by me.
> > 
> > Bye bye,
> > Wolfram.
> > 
> > 
> ----------------------------------------------------------------------
> > --- This SF.net email is sponsored by: Microsoft Defy all 
> challenges. 
> > Microsoft(R) Visual Studio 2005.
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> > plib-devel mailing list
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> > https://lists.sourceforge.net/lists/listinfo/plib-devel
> > 
> > 
> > 
> > 
> > 
> > 
> > 
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> > --- This SF.net email is sponsored by: Microsoft Defy all 
> challenges. 
> > Microsoft(R) Visual Studio 2005.
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> 
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Re: [Plib-devel] How many triangles in a leaf?

[John F. F. <joh...@cy...>]

Roma locuta est, causa finita est.  ("Rome has spoken, the matter is 
finished.")

Until the next time somebody brings it up and I forget again that it was 
settled before.

I have an application at work that writes a binary file and then puts a 
"table of contents" in the front.  If the file is smaller than 2^32 bytes, 
the entries in the table of contents are written in four-byte words; if it 
is larger, they are written in four-byte words.  Talk about accounting 
nightmares!

	- John


-----Original Message-----
From:	Steve Baker
Sent:	Sunday, September 23, 2007 2:57 PM
To:	joh...@cy...; PLIB Developers
Subject:	Re: [Plib-devel] How many triangles in a leaf?

I would strongly advise against this change.  Sending 32 bit indices
instead of 16 is a big penalty on reasonably size meshes.  It's not
hard to split big meshes into 65536 vertex chunks and it's a bad idea
to slow the package down for reasonably sized models just in order to
support the clueless.

John F. Fay wrote:
> If somebody can send me some patches I can put them into the code.  I 
have
> re-read Paolo's post and the responses and I do not want to make such a
> subtle change to a library that I do not know well.
>
> 	- John
>
>
> -----Original Message-----
> From:	Wolfram Kuss
> Sent:	Saturday, September 22, 2007 3:02 PM
> To:	PLIB Developers
> Subject:	Re: [Plib-devel] How many triangles in a leaf?
>
> I agree we should increase the limit.
> The argument that this will encourage bad models is only half true
> IMHO as often I have to work with finished models and am not even in
> contact with the modeller.
>
> I am using "unsigned short" instead of "short" for a long time now
> (probably 2 years or so) without issues. Going to unsigned int would
> probably be a bit more work, but would be welcome by me.
>
> Bye bye,
> Wolfram.
>
> -------------------------------------------------------------------------
> This SF.net email is sponsored by: Microsoft
> Defy all challenges. Microsoft(R) Visual Studio 2005.
> http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
> _______________________________________________
> plib-devel mailing list
> pli...@li...
> https://lists.sourceforge.net/lists/listinfo/plib-devel
>
>
>
>
>
>
> -------------------------------------------------------------------------
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> Defy all challenges. Microsoft(R) Visual Studio 2005.
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