On 15-12-2009 22:41, Warp wrote:
> andrel <a_l### [at] hotmailcom> wrote:
>> More importantly, what did we learn from this and why did you, warp, 
>> post this?
> 
>   Does everything have to have a reason behind it? 

Not always, but seemed to me a rather random post.

> Can't things be done just for the fun of it?

It would be much interesting for particularly this group if it had a 
theory of how we perceive things and what we don't see behind it. I was 
a bit hoping for something like that.

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>  How many triangles can you find in the attached image?

If this was a Project Euler problem it would state the answer, and then show 
a horrendously complex shape and ask for how many triangles were in that 
one, and it would probably be a 9 digit number or something :-)

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scott wrote:

> If this was a Project Euler problem it would state the answer, and then 
> show a horrendously complex shape and ask for how many triangles were in 
> that one, and it would probably be a 9 digit number or something :-)

What, like this?

http://tinyurl.com/y9h6cjz

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>> If this was a Project Euler problem it would state the answer, and then 
>> show a horrendously complex shape and ask for how many triangles were in 
>> that one, and it would probably be a 9 digit number or something :-)
>
> What, like this?
>
> http://tinyurl.com/y9h6cjz

Not quite what I had in mind, but LOLs nonetheless :-)

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>> What, like this?
>>
>> http://tinyurl.com/y9h6cjz
> 
> Not quite what I had in mind, but LOLs nonetheless :-)

There's A LOT of triangles there, I assure you. ;-)

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>> Not quite what I had in mind, but LOLs nonetheless :-)
>
> There's A LOT of triangles there, I assure you. ;-)

To me it looks like a few thousand at most in that picture, not a 
particularly detailed or smoothed model, and you're only seeing part of it. 
(Man the triangles around her neck and clothes are *huge*)

Here are 7.3 million triangles:

http://tinyurl.com/yav476n

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>> There's A LOT of triangles there, I assure you. ;-)
> 
> To me it looks like a few thousand at most

Which I would think qualifies as "a lot" in anyone's book.

> not a 
> particularly detailed or smoothed model, and you're only seeing part of 
> it.

It all looks so smooth and curvey...

...until you walk past a light source. Ah, the wonders of per-polygon 
lighting calculations. :-P

> (Man the triangles around her neck and clothes are *huge*)

So is her bust. :-P

> Here are 7.3 million triangles:
> 
> http://tinyurl.com/yav476n

I don't even want to *know* how much disk space that eats, do I? (Nor 
how long it took some poor soul to manually place 7.3 million triangles 
by hand...)

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> ...until you walk past a light source. Ah, the wonders of per-polygon 
> lighting calculations. :-P

I thought all games used per-pixel lighting now?

> I don't even want to *know* how much disk space that eats, do I?

I fired up Blender and applied sub-surface to the Monkey mesh to 6 levels 
(it seems that's the maximum allowed).  That gave me 2 million "faces" (4 
million triangles I assume).  I made a copy of it, so there were 8 million 
triangles being displayed.  Blender told me it was taking up 372 MB and I 
could still navigate around the scene in real-time (maybe around 5 fps).

It seems the best nVidia cards (eg GTX 295) have a graphics bandwidth of 
almost 20x what I have and 4x as much RAM, so I suspect you'd be able to 
edit and work on well over 20 million triangles with no problem on a 
high-spec machine.

> (Nor how long it took some poor soul to manually place 7.3 million 
> triangles by hand...)

LOL, for the 5325th time, nobody manually places the triangles by hand, they 
are calculated automatically by the computer using a subdivision algorithm. 
Here is an example of the base mesh that was actually drawn by hand:

http://tinyurl.com/yavvpgx

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>> ...until you walk past a light source. Ah, the wonders of per-polygon 
>> lighting calculations. :-P
> 
> I thought all games used per-pixel lighting now?

Apparently HL2 doesn't. (They've upgraded the Source engine several 
times since then, so maybe it does now. I doubt it.)

>> I don't even want to *know* how much disk space that eats, do I?
> 
> Blender told me it was taking up 372 MB

Ouch. That's a hell of a lot of space for one single model. God only 
knows what an entire scene from something like Cars takes...

> and I could still navigate around the scene in real-time 
> (maybe around 5 fps).
> 
> It seems the best nVidia cards (eg GTX 295) have a graphics bandwidth of 
> almost 20x what I have and 4x as much RAM, so I suspect you'd be able to 
> edit and work on well over 20 million triangles with no problem on a 
> high-spec machine.

I have a GTX 280. It tells me it has several hundred cores. This makes 
me very happy. (It does not, however, make Crysis run smoothly...)

>> (Nor how long it took some poor soul to manually place 7.3 million 
>> triangles by hand...)
> 
> LOL, for the 5325th time, nobody manually places the triangles by hand, 
> they are calculated automatically by the computer using a subdivision 
> algorithm. Here is an example of the base mesh that was actually drawn 
> by hand:
> 
> http://tinyurl.com/yavvpgx

That still looks impossibly complex to draw by hand.

Look at the belt. It's circular. Ever tried drawing a circle using 
pencil and paper? (Hint: It's physically impossible.) Sure, you can move 
the verticies around after you've drawn them. But it would still be 
hopelessly hard to arrange 80 points into a near-perfect curve like 
that. And that's just making the outline; next you have to somehow model 
the height of the belt, not to mention its thickness. Impossibility upon 
impossibility.

Also... no triangles. Only quadrilaterals, as far as I can tell.

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Invisible wrote:
> Look at the belt. It's circular. Ever tried drawing a circle using 
> pencil and paper? (Hint: It's physically impossible.) Sure, you can move 
> the verticies around after you've drawn them. But it would still be 
> hopelessly hard to arrange 80 points into a near-perfect curve like 
> that. And that's just making the outline; next you have to somehow model 
> the height of the belt, not to mention its thickness. Impossibility upon 
> impossibility.

I like how you try to demonstrate how something we see a picture of is 
in fact impossible to do :-)

-- 
Vincent

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