[Sidefx-houdini-list] Some hom question

Graham Thompson captainhammy at gmail.com
Fri Apr 2 17:06:06 EDT 2010

1.  If you want the world space position you'll need to multiply the
position vector by the world transform of the parent object.
sopnode is an instance of hou.SopNode
point_pos = sopnode.geometry().iterPoints()[0].position()
parent_xform = sopnode.parent().worldTransfom()
world_pos = point_pos * parent_xform

2. From a mathematical standpoint you can't actually divide a vector.
To divide a vector you want to multiply it by the inverse of what you
wish to divide by.

For example. to do what you want you can just do
vec = hou.Vector3(3,3,3)
vec = vec * (1.0/3)

This performs a multiplication of your vector by the value 1/3, or 0.333.

3. If you want to delete all the geometry all you have to do is call
hou.Geometry.deletePrims(hou.Geometry.prims()).  It also gives you the
option of keeping all the points.

4. You can get geometry from input objects by going
hou.SopNode.inputs()[inputnum].geometry().  This geometry is read-only
though.  If you want to merge it into the main geometry you can call

On Fri, Apr 2, 2010 at 1:42 PM, Sheldon Serrao <emailsheldon at gmail.com> wrote:
> I apologize if these questions have been answered before.
> 1) When I query the position of a point on a geometry, how can I get
> the world space of that point? I tried geo.prims() but it gives me in
> the local space. If the user is going to have multiple objects on the
> top level it would be hard to actually traverse all transformations.
> 2) Right now I am trying to rescale my vector like so:
> vec = hou.Vector3((3,3,3))
> vec[0] /= 3
> vec[1] /= 3
> vec[2] /= 3
> this is a lazy request but it would be nice to have a vec /= 3
> 3) just like a scatter sop, how can one say "ok delete all incoming
> geometry but only output a single point for me?"
> 4) how can I get the incoming geometry data from the input of my
> python sop geometry node? If I have 3 inputs for example, how can I
> ask hom to give me geometry from input2 or input3?
> Cheers :)
> Sheldon
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