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

Sean Lewkiw seanl at rainmaker.com
Wed Jun 13 11:30:33 EDT 2007


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 Lewkiw
Rainmaker Digital
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London W1D 5EU
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