[Sidefx-houdini-list] Point instancing at object level inheriting point colours

Sean Lewkiw seanl at rainmaker.com
Wed Jun 13 11:56:36 EDT 2007

That's the ticket!  Thanks, that's better than running the geo through a 
ugly tcl, (YES!  LONG LIVE tcl !!!) script.


Louis Dunlevy wrote:
> Usually works fine.
> Turn off "use indirect references"
> If you copy the shader string from  the spreadsheet and paste it into 
> an attribute create sop you can vary the parameters.
> "op:/shaderpath/shader" "float moveP" [ $BLAH]
> Sean Lewkiw wrote:
>> Hi,
>> I've got a tree to which I'm instancing a bunch of leaves.  Works fine,
>> but now I want to add some noise.  My shader is a VOP network that uses
>> paramater VOPs that take a Cd input.  Of course, if Cd is available in
>> the geo, the VOP uses that.  Fine.
>> Now I want this to work for instancing.  In the instance object, I apply
>> a SHOP SOP.  I make sure 'generate point attributes for instancing' is
>> on.  In the spreadsheet, there is now a call to my shader as if I were
>> calling it from the command line for each point.  Great, except Cd,
>> which exists as a point attribute on each point, is set to 0,0,0.  So
>> when I point instance the geo onto this object, all the Cd is the same.
>> I checked the archives and Mark E had posted an example, but of course
>> that's not archived.  He does say:
>> Mark sez, (and I quote):
>>> The important things to look at are:
>>> - The expressions for the diffuse color in the plastic SHOP (in
>>> the points object)
>> I assume that the shader itself has some kind of expression that tells
>> it to fetch the diffuse value from the object's point that is calling
>> it.  What kind of fancy schmancy voodoo might this be?
>>> - The shader SOP is creating hard strings on each point rather
>>> than indirect references to the SHOP (so that stamping works)
>>> - The shader SOP creates point shaders (rather than binding to the
>>> primitives).
>> Anyone have any ideas?
>> Sean
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Sean Lewkiw
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