Hello Nathan,

What a lot of job from you again!!

There are a simple rule to find the good way to implement normal:

1) When you scale UNIFORMLY an OBJECT, and if you place the camera 
   in a proper way, you cannot see a change for the normal (and also 
   for the complete texture!!).

2) When you scale NON-UNIFORMLY an OBJECT, you can see a difference 
   for its normal (and also for its texture), because the modification 
   are not the same in all direction. One can also understand this as 
   follow: because the scaling is NON-UNIFORM, you don't have the same 
   object at the end of the scaling and its texture must follow this 
   change also! But when you scale UNIFORMLY en OBJECT, in fact, you 
   get the same object! You can see that there are a scaling only if 
   the object is compare to another (which is not scale). With other 
   words, if I scale a scene uniformly, I get the same scene, exactly 
   the same scene!
   
3) When you scale UNIFORMLY a NORMAL, of course, you must see a 
   difference for the appearance of the surface of the object 
   (you get a different object: it keeps the same shape but not 
   the same surface). 
   Because here, by scaling the normal, you change the 
   caracteristic of the surface. But this must be uniform in all 
   direction. So there are wider and deeper, slope unchange.

4) When you scale NON-UNIFORMLY a NORMAL, you must see a difference 
   also but the change is no-uniform so the slope will change.

Remark : the points 2) and 4) are automatic and come from the points 
         1) and 3). When you make the code to implement 
         the point 1) and 3) (value for scaling for x = value for 
         scaling for y = value for scaling for z), if you put now 
         different value for the scaling along each axis, you will
         get the behavior describe for the points 2) and 4) 

All this behavior are not a question of felling this must be like it.
This is logical. Moreover all other soft work like this (even if this is
shader instead of texture/material)

So here is my answer:

1) A
2) B
3) A
4) A
5) B
6) A

Ho! I am just looking the other message and I see that we are ok with 
this :)

Thank again Nathan for your work!

Fabian.
 


Nathan Kopp wrote:
> 
> I am wondering what people really think about how normals and scaling should
> work.  If you're interested in this topic, please see this page and take the
> 'surface normal survey'.  You can reply by emailing me or reply to this
> post.
> 
> http://nathan.kopp.com/normals.htm
> 
> -Nathan

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