How do I access Local Variable?

[dangerweenie]

Hi there,

I'm learning the ins and outs of working with attributes, passing them between nodes, etc. Maybe someone could help me out with this ...

I need to scale parts of an L-System's branch width ($WIDTH, when working downstream from the L-System node).

The Houdini help file says that "W" is a point attribute - however when I middle click on the node, or open the detail view window with the node selected, the only point attributes I can see are x y z, u v, etc.

I am trying to use a sphere primitive to influence the scale of the L-System via an AttributeTransfer SOP, so that when the sphere is intersected with the L-System (kind of like using the metaball as an input for clipping), the "$WIDTH" attribute is taken from the sphere and placed onto the points of the resulting polyWire SOP or just L-System out. I can't find the right names to use. I don't even know how to view the attributes I am interested in, in some kind of spreadsheet or viewport display or something. lsystem.hiplsystem.hip

Can anyone help me out?

Thanks,

Matt

PS - I've attached the file, though it's not much.

[ehsan parizi]

check this out

lsystem_2.hipnc

[dangerweenie]

check this out

wtf? thank you!

I don't understand why it didn't work for me, I tried doing the exact same thing, except I specified the "source" and "target" groups within the AttributeTransfer SOP. If I do that in your scene, it breaks ... any idea why? Is it because the resample doesn't get included in the group name?

Also, do you know a good way to audit / view these internal attributes? Like I said, no luck in the "geometry spread sheet" or "details view".

Thanks again for all the help you've provided on the board here.

Best,

Matt

[ehsan parizi]

You're welcome Matt.

Your setup had one big problem. you were telling polywire to use $WIDTH while your attribute is called $W

you can view all of your attributes in detail view. but I personally would like to make a color attribute based on my new attribute to make is visible in the viewport. I did the same thing in the file that I uploaded too. I probably should have named it visualization.

[dangerweenie]

You're welcome Matt.

Your setup had one big problem. you were telling polywire to use $WIDTH while your attribute is called $W

you can view all of your attributes in detail view. but I personally would like to make a color attribute based on my new attribute to make is visible in the viewport. I did the same thing in the file that I uploaded too. I probably should have named it visualization.

Hi Ehsan,

I am looking in the viewport, and I turned on all the custom display options for 'normal geometry' - even made one and linked it to 'w' - still don't see anything though.

i tried it earlier in a different scene, and it worked. not working now, though. is there a specific way to view these attrs?

thanks,

matt

[dangerweenie]

Hi Ehsan,

I am looking in the viewport, and I turned on all the custom display options for 'normal geometry' - even made one and linked it to 'w' - still don't see anything though.

i tried it earlier in a different scene, and it worked. not working now, though. is there a specific way to view these attrs?

thanks,

matt

also, this is weird, but i am able to get the attributeTransfer SOP to work when specifying the input group names explicity (in the parameter interface), but only if I disable the "resample" SOP before it. If I don't the mesh looks very disconnected and broken apart. I wonder if this is because the points are being reordered or something?

[ehsan parizi]

Hi Ehsan,

I am looking in the viewport, and I turned on all the custom display options for 'normal geometry' - even made one and linked it to 'w' - still don't see anything though.

i tried it earlier in a different scene, and it worked. not working now, though. is there a specific way to view these attrs?

thanks,

matt

like this?

lsystem_3.hipnc

[ehsan parizi]

also, this is weird, but i am able to get the attributeTransfer SOP to work when specifying the input group names explicity (in the parameter interface), but only if I disable the "resample" SOP before it. If I don't the mesh looks very disconnected and broken apart. I wonder if this is because the points are being reordered or something?

You can decrease the Length in resample, or just simply ignore it, I added that to test something actually, You can delete that resample node.

[thx1138]

another way to give some random attribute on laeves:

Premise:FA

Rule1:A=//////B

Rule2:&FAJ(1,,rand(x)*0.02)

rand(x) uses an x component of a current turtle position in space. And it is acceptable in some cases.

But i failed to try use fit(rand(x),0,1,0,0.1) instead of rand(x)

Edited August 20, 2012 by thx1138