centroid in pointWrangle

[haggi 41]

Hi,

 

I try to get the centoid of an object in a pointWrangle node. First I added a float3 attribute to the pointWrange and set the values of this attribute to the centroid of my object like: centroid("../myCube", D_X) etc. This works fine, the values are updated. Now I try to use this attribute in my pointWangle code  with: `chs("centerAttribx")`. But it seems that this procedure does not update the values in the pointWrange node.

 

My solution is to create a point with an add node set the position of the point to the centroid and plug this node into the second input of my pointWrange node. This works so far, but I'd like to know if there is a more elegant way to get the centroid directly from within a pointWrangleNode.

 

[rayman 458]

well, chs returns string - in your case chv should work.

[haggi 41]

Thanks.... sometimes I feel so stuipd...

[wick3dParticle 2]

Hi Haggi,

 

I was wondering if you could share that file with us. I was under the impression that you can't run Houdini expression language in wrangle nodes, and that you were limited only to VEX. I would love to learn how you got that to work. I have tried using expressions like centroid() in the past, but remember getting errors due to that.

Thanks,

Ilan

[pbarua 44]

centroid() doesn't work in vex.

Create a 3float (or vector) spare parameter on wrangle. use centroid() expression there and then reference that parameter in wrangle using ch() function.

[wick3dParticle 2]

Ah, got it. I think I misread the original post. Thanks Pradeep!

 

~Ilan

[rayman 458]

This should work too (VEX only):

vector min, max;
getbbox(min, max);
vector center = (min+max)/2;

Edited December 18, 2014 by rayman

[wick3dParticle 2]

Thanks Rayman.

 

Yes, that's what I have been using.

 

~Ilan

[Mzigaib 20]

What would be the best way to get those initial 'min' and 'max' vectors from the geometry?

Thanks.

[Mikal 4]

 

The min and max vectors are returned by the getbbox() function. 

In H16... you can get the same result with getbbox_center().

 

[Mzigaib 20]

I though I would have to come with the vector min,max myself which really doesn't makes much sense.

 

Thanks!

[Nicholas Ralabate 20]

fwiw, the vex snippet above seems to produce a different value than the extract centroid SOP (which can also create a centroid attribute)

[nuki 39]

promoting P to a detail attribute (by avg, min/max etc.) can be a useful trick too!