HI
I am currently figuring out how connectivity sop works. According to the help document, it assigns a “class” attribute on each connected point but how can I alter each value of that “class” attribute? Anyone got any example on it? (since the help document does not have any example on it)

Thank you very much for your attention!

Your question is really about attributes. In any pane hit ALT+4 to see the attribute view. Change the menu in that pane to view points or primatives attr's, click on (select) the connectivity sop, and you should see the “class” attribute from the connectivity sop (assuming you haven't changed the name). In Sop's, if you hit tab you'll see a sub-menu “Attributes” which contains a bunch of sops which will manipulate attributes.

Here's a simple example. I have a box sop, appended to a copy sop: 3 copies spread in x (translate=2, translate is cumulative). Append a connectivity sop and MMB on the sop. You'll see 1 Primative Attribute class. Also, you'll see a mapping below class -> CLASS. This means you can refer to those attributes in expressions elsewhere via the $CLASS variable! Append an attribute create sop. Set the name to “newclass” and set the Value to “$CLASS+100”. In the Attribute Pane you should now see a 2nd column “newclass”. Append an attribute sop and rename “primative” attr ‘class’ to ‘renamed_class’, or delete the old attribute. etc etc.

The “point()” expression allows you to access point attributes. In the textport run “exhelp point”.

When creating geometry which will be fed into RBD dops, the connectivity sop partners with the partitiion sop. They let you “break up” geometry into parts (based on groups obtained from these two). If you dig around the DOP's examples (eg. RBD Fractured Object DOP) you see the duo time and time again.

for more info, see the Houdini Doc's, eg: hdox/houdini/content/base/model_attrs.html

i hope that helps a bit. b.

PS. An example of the partition & connectivity sop came up today in another topic: http://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&p=30070#30070 [sidefx.com]