Deformation Wrangle

[Yader]

Can someone explain the difference between point wrangle and deformation wrangle? What kind of advantages has it over the other wrangles? Or even give some examples in action? Thanks in advance.

The help didn't help

Edited October 24, 2015 by Yader

[symek]

DeformationWranger computes the difference between input geometry and geometry as deformed by your code and uses it to transform vector attributes according to change of P, so attributes like N or v or up will follow deformation (it seems orient, which is quaternion, is omitted though). The advantage is that you don't have to compute it by yourself, which is sometimes difficult or boring or both. 

 

In a way it's similar to an old AttributeReorient SOP, which seems to give much worse results though and uses different method. 

deforWranger_example.hipnc

[Yader]

Thanks very much Symek, that helps a lot to understand this Wrangle. 

Also how you knot together a stable matrix for generating the orient attribute 

gave some insight, as matrices/rotations aren't so easy to grasp inside Houdini.

Edited October 24, 2015 by Yader

[magneto]

Does this work on point clouds? If you have points with no surface or just polygon curves, reading P from the second input, doesn't transform attributes correctly. You just get them as 0,0,0.

 

Is there a way to do this?

[anim]

the whole point of deformation wrangle is that it computes correct orientation from applying deformation not only to points, but to position derivatives therefore it works even for just a pointcloud

however, the deformation must be defined in the Deformation Wrangle snippet code

[magneto]

Thanks anim, I was talking based on Symek's file which simply reads the second input. It didn't define the deformation. Is there a way to reorient normals if the deformation is defined elsewhere? AttribReorient didn't work either.

[anim]

attrib reorient works if the deformation is defined somewhere else, however it will not work on isolated points as there is no reference frame to compare

if you have 2 pointclouds with the same number of points, one scrambles (deformed)

would you be able to tell how each point should rotate just based on the positional difference between points?

what exactly are you trying to do?

[magneto]

I have a set of points I am deforming (bend, twist, etc), they have normals and then I want to be able to get their normals transformed based on this. I want it to work on other deformations so I wouldn't be able to define the deformation inside DeformationWrangle.

 

I am using a polygon curve to define the deformation just like a wire deformer so I am wondering if I could be able to transform the normals of the points being deformed using the polygon curve? I think even wire solver doesn't do this, right? I see the normals and other vectors simply pointing in the same direction.

[anim]

you'd either need to define the deformation inside of the Deformation Wrangle as mentioned, have a look at the new Bend SOP (which does twist and taper as well) it is using the Deformation Wrangle inside so it will work on pointcloud to transform all attributes properly

or you can compute xform attribute yourself and use Transform By Attribute SOP to transform all attributes according to it