newbie question: Why does a NURBS cube fall apart?

[Soulcre8er]

Its a little bit more complicated than the diff sides falling apart, when you create a nurbs cube the sides your talking about are all in one group, if you hit the up arrow key you can go up the hierarchy where all the side are in.The reason why a nurbs cube have seperate side is basically because you cant connect all the side together like a polygon.

[Jozvex]

Yeah, because NURBS like to be smooth all the time, a cube made out of NURBS doesn't really work. So it's really just 6 NURBS planes grouped in the right shape.

If you open up the Outliner (Window > Outliner) you can see that there is a group node with 6 plane surfaces in it. Select that group node to move/rotate/scale the whole 'cube'.

;)

[Mooncalf]

Ah, I think I understand...

So are NURBS cubes used often? Or do poly cubes pretty much fit the bill for any right-angled flibbrty-gibberty?

Why include NURBS cubes at all if, as you say, NURBS don't really conform well to cubism?

- M

[Kabab]

Just because they arn't attached doesn't mean they are not usefull.

Generally nurbs are good for precise hard surfaces like car bodies, because they are parametricly calculated you can produce very high quaility surfaces.

Where as poly's are great for really organic stuff like people and monsters :p

[playmesumch00ns]

Originally posted by Mooncalf
Why include NURBS cubes at all if, as you say, NURBS don't really conform well to cubism?

I've often wondered this as well. I always thought NURBS cubes were more of a post-modern take on neo-futurism.

[Mooncalf]

Originally posted by Kabab Generally nurbs are good for precise hard surfaces like car bodies, because they are parametricly calculated you can produce very high quaility surfaces.


Ah, I think I'm beginning to understand. Thanks. :)

Originally posted by playmesumch00ns
I've often wondered this as well. I always thought NURBS cubes were more of a post-modern take on neo-futurism.


Touche. ;)

- M

[alesmav]

Because of it's UV parametrisation EVERY NURBS surface has 4 sides or "edges" if you want. Yes, even the sphere which has 0 length edge on top and bottom poles. For this reason it is impossible to make nurbs cube a single object. And because of this 4-sided nature of NURBS surfaces a patch modelling technique has been developed. When you hear a character has been patch modelled it simply means it was built with (very often) hundreds of NURBS surfaces put next to each other so it looks like it's a single surface. Of course it's a very tedious job cos you have to achieve a flawless tangency between those surfaces so that no seams are visible. Plus it's very tricky to texture and deform the whole patch group. That's why now mostly polygons and subd's are used for characters. They are so much easier to manage.

ALES

The best way to see how a NURBS surface flows is going to the Isoparm mode and dragging across the NURBS surface.

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