Manipulate on a primitive level

[Pancho]

Is it possible to do this at a primitive or per group level without any loops? The deformer is pretty simple (radial move with offset based on distance to center). I tried to script it as an expresion into the primitive transformations. But just getting the length of a vector is a nightmare, since length() needs an x,y and z input. Why isn't it enough to enter length(vector name)?

 

O.k., average P is just an attribute, P promoted from Point to Prim with Average.

 

All is done on a per point basis in an attribute vop. Tried it in a Prim Vop, but changing P wasn't possible, so I guess P isn't the Prim center position.

 

So, what's the way to do this?

 

Thanks in advance

Thomas

 

 

Edited November 22, 2015 by Pancho

[Pancho]

Sorry, now idea why the attachment didn't upload the first time.

[Pancho]

Nobody?

 

I know that you can move primitives with the primitive node, BUT how would I calculate the transforms for it? This example is working on a per point level. I first need to average and promote the position and custom attributes to primitive level and then back to point context in order to have the same value for each point of the primitive.

 

With expressions in the Primitive node you can achieve some small calculations, but nothing complex. So, which way do I need to go in Houdini to do something like the node tree above on a primitive  (or group) level? Without a for each sop!

 

Don't want to learn wrong manners in Houdini...

 

Cheers

Tom

[amm]

 

All is done on a per point basis in an attribute vop. Tried it in a Prim Vop, but changing P wasn't possible, so I guess P isn't the Prim center position.

 

So what you're trying to do. By the way, if Attribute VOP is running over primitives, you could export P, which is a center of primitive (or average of points, not sure). But, promoting to points could return something useful in case of disconnected polygons, curves or so. Otherwise, when each point 'belongs' to many primitives, I don't think so.

[mestela]

Here's a way, stealing a trick Anim posted a couple of years ago ( http://forums.odforce.net/topic/16837-is-it-possible-to-fuse-points-with-the-same-attribute-values/?hl=fuse )

 

If you run a fuse in unique mode to split each face, then an assemble sop, each face is packed, meaning you manipulate it like a point. After you distort the packed faces they naturally become separated, so anims trick is put a rest before the distort, then in a wrangle store the shifted positions, swap to the rest pos, fuse sop, then restore the shifted positions again.

 

 

prim_distort.hipnc