selecting inside/outside primitives

[archoudini]

Hi All,

I am a maya user and I have recently started learning Houdini and was looking for a procedural way of selecting inside or outward faces of for say this glass geometry. 

thanks

 

 

[f1480187]

No general way. Try select points by bounding object created with Shrinkwrap SOP. Then convert point group to primitives.

select_inside.hipnc

[friedasparagus]

The group SOP does have an option to group primitives by normal relative to another object (or the object itself). Just drop down a group SOP and then go to the normal tab, click enable and in the 'backface from' field select the reference object (in the case of the glass, if the geometry is centered, you can select the object itself)... I hope that makes some kind of sense

EDIT: Of course, if you can, it might make more sense to create the geometry in a procedural way and then you can generate your groups as you go, for example if the glass was created from an extruded tube, the PolyExtrude SOP allows you the group the extruded faces... This of course doesn't cover the event when you've been given a finished geo by some other bod that you've got the wrap your head around :o)

Edited April 24, 2016 by friedasparagus

[archoudini]

34 minutes ago, friedasparagus said:

The group SOP does have an option to group primitives by normal relative to another object (or the object itself). Just drop down a group SOP and then go to the normal tab, click enable and in the 'backface from' field select the reference object (in the case of the glass, if the geometry is centered, you can select the object itself)... I hope that makes some kind of sense

EDIT: Of course, if you can, it might make more sense to create the geometry in a procedural way and then you can generate your groups as you go, for example if the glass was created from an extruded tube, the PolyExtrude SOP allows you the group the extruded faces... This of course doesn't cover the event when you've been given a finished geo by some other bod that you've got the wrap your head around :o)

thanks Henry, "backface from" option is what i was looking for

[archoudini]

51 minutes ago, friedasparagus said:

The group SOP does have an option to group primitives by normal relative to another object (or the object itself). Just drop down a group SOP and then go to the normal tab, click enable and in the 'backface from' field select the reference object (in the case of the glass, if the geometry is centered, you can select the object itself)... I hope that makes some kind of sense

EDIT: Of course, if you can, it might make more sense to create the geometry in a procedural way and then you can generate your groups as you go, for example if the glass was created from an extruded tube, the PolyExtrude SOP allows you the group the extruded faces... This of course doesn't cover the event when you've been given a finished geo by some other bod that you've got the wrap your head around :o)

 

1 hour ago, f1480187 said:

No general way. Try select points by bounding object created with Shrinkwrap SOP. Then convert point group to primitives.

select_inside.hipnc

thanks F1 for the hip file....  select by bound option also worked