UV's are a Vector4 so that 3D texture volumes can be supported.  They're not 
currently but it seemed prudent to not design in a limiting factor to the uv 
attribute.  It also matches OpenGL.

Just set Z to 0, it should be ignored by the current shading system.

fwiw the ordering of the vector is defined in the Vector4.h header file - 
x,y,z,w.

-jonathan


On Feb 27, 2012, at 2:16 AM, Julik Tarkhanov wrote:

> So I've gotten to writing a UV manipulator node, and so far whipped something 
> up real quick based on a mix of LogGeo and UVProject.
> Seems to be working, however there is something I don't really get with 
> regards to attribute storage.
> 
> Currently I have to manipulate copied UVs with Vector4 attributes, like so 
> 
> https://gist.github.com/3d6a6997a14110f92ed5
> 
> and once I copy the data from the vector into itself using set() I have to 
> feed in all the 4 values. What perplexes me
> is why there is 4 of them? I can understand the UV are the two dimensions, 
> then there's W, but what is Z? And what is the ordering
> of the values in the vector? The documentation is almost silent on that.
> 
> I can retreive the atribute as Vector2 but the manipulation creates a really 
> weird result visually, as if I am missing dimensions.
> 
> Would appreciate if someone could explain that. UVTile from Jonathan is not 
> really the best example since it works in shader space.
> 
> -- 
> Julik Tarkhanov | HecticElectric | Keizersgracht 736 1017 EX  
> Amsterdam | The Netherlands | tel. +31 20 330 8250
> cel. +31 61 145 06 36 | http://hecticelectric.nl
> 
> 
> 
> 
> 
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