Otl Reading A String Outside

[peliosis]

I'm making a curve width visualize otl, it's easy and almost done, but there is one flaw I can't omit.

Instead of going into the otl and typing an expression into attribute value of attribcreate sop I'd like to write it into my otl parameter window.

I created a string parameter in my otl and connected attrib create from inside this otl via ch("../../blah/my_string_parameter") or chs.

It works with numbers and expressions (in backticks) as long as the expression doesn't make use of local variables like $PT.

I'd like to create a link which would not read this expression in otl level but inside it. To put the same expression as is into inside attribcreate and evaluate it there.

Hope I made myself clear, are there any clues?

[sibarrick]

Try chsraw

I think that delays the evaluation of the string until the sop gets hold of it

[peliosis]

Try chsraw

I think that delays the evaluation of the string until the sop gets hold of it

28117[/snapback]

It works half way...It produces a plain string when I put echo`exp` in textport but not the effect wanted.

k_showidth_02.hipnc

[sibarrick]

It works half way...It produces a plain string when I put echo`exp` in textport but not the effect wanted.

28120[/snapback]

Sorry, try this

evals(chsraw("../width_value"))

[peliosis]

Sorry, try this

evals(chsraw("../width_value"))

28122[/snapback]

I'd never figure it out, thanks a lot it works great now!

I'll post my otl after finishing, now I'm working on getting width from custom channel, curve or just chops.

[peliosis]

I ended some phase and post a result, If anybody could tell me why $F expression doesn't work in the expression field I'd be grateful.

I thought of something like this from the beginning of my houdini experience, after using 3ds max loft with similiar functions.

I'm going to improve it to a series of tiny otls.

If you have any ideas for improvement or any critics please share. This is mostly for training.

Thanks

k_showidth_02.hipnc

[TheUsualAlex]

I ended some phase and post a result, If anybody could tell me why $F expression doesn't work in the expression field I'd be grateful.

I thought of something like this from the beginning of my houdini experience, after using 3ds max loft with similiar functions.

I'm going to improve it to a series of tiny otls.

If you have any ideas for improvement or any critics please share. This is mostly for training.

Thanks

28133[/snapback]

Hello,

in your fetch_widthcurve, change the Channel Range to "use Start/End", and then in your Start field, type $RFSTART and End field, type $RFEND.

Hope that's what you're looking for.

Take care,

Alex

[peliosis]

Thanks but no , it does constrain channel length to animation length but this is not the case.

If you try putting an expression using $F or $FF into "width_val" of the otl, you'll notice that it doesn't work, so it's impossible to make automatic animation of eg. sinus or anything using current frame.

I don't know why id doesn't work, Ithought $F is a global variable.

[sibarrick]

I ended some phase and post a result, If anybody could tell me why $F expression doesn't work in the expression field I'd be grateful.

28133[/snapback]

Not sure I follow what you mean here, if I put $F in your expression field and press play the width changes for each frame as I'd expect. Could you post an example with it not working?

If you mean how to make it read an animation curve that has an expression in it based on $F take a look at the attached.

You need evals not just eval

k_showidth_si.hipnc

[peliosis]

Thanks for the example.

I meant that when I put "clamp(sin($PT*$F+8)*20,5,20)" (the same expression only $F instead of a number)

it doesn't work but gives blank viewport and red triangle.

When I put $F alone or sin($F)*100 it works ok.

When I combine $F with $PT there is a problem.

[stevenong]

Please try eval(chsraw("../width_value")) instead of evals(). eval() will constantly evaluate the expression while evals() seems to evaluate it just once.

Hope the above helps!

Cheers!

steven

[edward]

You shouldn't use evals(). The difference between eval() without an s and evals() with an s is the fact that the former returns a float while the later returns a string.

[sibarrick]

Interesting, how come my example doesn't work if you eval but does if you use evals like I did?

I thought that by using evals it returns a string that is then parsed correctly by the parameter as a written expression, however if you use eval it fails because eval can't evaluate the $PT and $F parts correctly.