Hi,

I have a simple question.

What's the difference between “@” and “$”? For example, @N.x vs $NX
I had a sphere with polygon and added a ‘point’ node.(see attachments)

And then I added ‘Normal.’ The default values were @N.x, @N.y, @N.z. But as you can see in the geometry spreadsheet it gave me all 0s. But when I changed those to $NX, $NY, $NZ it gave me correct normal values. Is this a bug? I have the latest Houdini running on Mac OSX 10.11.

Thanks,

HB

The @ symbol denotes an attribute added to a context, such as Points, Primitives, Detail (global to the object). When you reference an attribute and it does not exist Houdini creates the attribute for you and sets it to zero.

$ variables are built-in values that you can use.

So you created a new attribute which got set to zero.
Then you referenced a global value via the $.

Thanks Enivob,

If it's not too much trouble can you give me an example when you use @(attribute) over $(global value?)?

If I understood correctly “@(attributes)” are the innate properties of an object and “$(global value)” are the properties that can be determined globally, like 3rd point of view? Is that why point positions, @P.x and $TX has no difference?

Thank,

Hb