I'm having a hard time understanding what the point node does. I've read the docs, I've seen a couple of examples. I study them, I read.. but I haven't a clue what the heck it's actually doing and what I can do with this node.

Can anyone give me a dummy run down on this thing?

Thanks.

Moin,

I hope that these thoughts are of some help:

Houdini differentiates between points and vertices. The later are properties of polygons (in Houdini polygons are the simplest form of “primitives” and therefor called primitives) and have no “global meaning” all by themselves. Points however are what you would know from any 3d tool out there: “Points in space” - their main property is a position.

If you want to deform a mesh but keep its overall topology intact, meaning: each polygon keeps its vertices and their order, you just want to change the positions of the points making up the polygons (and this the shape of the mesh), you need to edit the positions of the points.

Positions are attributes of points.

To edit positions of points (and by that changing the shape of polygons) you use the point node, which allows you to change any attribute on a point group piped in.

Another use case would be to change the way UVs are laid out on a mesh. Imagine you have a few frames of an animation stitched together on a single texture file and want to project the animation running onto some surface. Then what you can do is have the surface point-dependent UVs and, over time, change the UV values of the surface's points to “jump” from frame to frame on the single texture.

In quintessence, the point node allows you to do things to the “basic construction entities of geometry in Houdini space, called points”

Does that make sense - maybe even more sense than what you already read?

Marc

Marc, thank you, all that helps immensely! I kept attaching the point node to some geometry and while playing with the settings nothing seemed to be happening. Then I realized that their were keyframes already attached to this node with some VEX code?

Makes it bit difficult to understand but I can see that the point node allows us to override point properties, is that how to look at it?

Hi,

> the point node allows us to override point properties, is that how to look at it?

… I'd say: Yes - and then I'd add “only that it's attributes, not properties, since the later could only be added by the Houdini devs” :-)

But, yes, I think you're on the right track.

Marc

timot.mo
Then I realized that their were keyframes already attached to this node with some VEX code?

these are actually Expressions, that may or may not be representing animation.
they are on the Point SOP by default mostly as a hint to knowing what the attributes are called (@P = position, @N = Normal etc).
Matt Estala has some good info on vex expressions and the point SOP here : http://www.tokeru.com/cgwiki/index.php?title=Houdini#Point_Sop [tokeru.com]

Awe you guys are awesome, thanks Arctor for that link. Thanks Marc!