Undeclared Wrangle Variables Are Always Floats (0.0)

[Atom]

Hi All,

 

I am watching Ari Danesh video on the PointWrange, introduced in H12.5

 

His example no longer works in H14.

 

In this scene the VEX code should randomize the Y points on the grid but the point wrangle seems to have no effect. What am I doing wrong?

ap_point_wrangle_porblem.hipnc

Edited June 15, 2015 by Atom

[Skybar]

You have a typo there, two of them. Your attributes is called "rnd_y" and "rnd_v" - but later you use "rand_y" and "rand_v" that doesn't exist.

[Atom]

Ah, thank you..(again).

 

That does seem odd to me, however. Shouldn't undeclared variables throw an error in the Wrangle node itself? (or at least a warning)

 

For instance if I simply type a single line @my_var;  (which is of an unknown type) I get a float attribute in the Geometry sheet with a value of 0.0. It seems the act of using a variable declares it as a float and initializes it with 0.0. That is why my mis-spelled variable produced no errors. A mis-spelled variable is a declared variable. And with it's value being zero it did not make any change in the y-direction. Because multiplying by zero is zero.

 

This certainly compounds the end-users ability to detect errors based upon typos. Ugh..

Edited June 15, 2015 by Atom

[anim]

Ah, thank you..(again).

 

That does seem odd to me, however. Shouldn't undeclared variables throw an error in the Wrangle node itself? (or at least a warning)

 

For instance if I simply type a single line @my_var;  (which is of an unknown type) I get a float attribute in the Geometry sheet with a value of 0.0. It seems the act of using a variable declares it as a float and initializes it with 0.0. That is why my mis-spelled variable produced no errors. And with it's value being zero it did not make any change in the y-direction. Because multiplying by zero is zero.

 

This certainly compounds the end-users ability to detect errors based upon typos. Ugh..

undeclared variables throw error and everything is as expected

the difference in your case is that you are not using variables, but attribute bindings

so @attribname, automatically binds that to an attribute and if that attribute doesn't exist it will be created and initialized with specified type(if specified by Attributes To Create pattern)

your example using actual variables would look like

vector pos = set(0,1,0);
float rnd_y = random(@ptnum);
vector rnd_v = set(0,rnd_y * 3.11,0);
@P += pos + rnd_v;

if you misspell variable names in there you would see errors

[Atom]

Got it, thanks Tomas.

 

Ari Danesh explained the difference between temporary variables and @variables later on in the video. I guess I should I have watched the entire video before posting.