[Sidefx-houdini-list] local variables in VOP SOPs

Jerry Corda-Stanley jerry at intelligentcreatures.com
Tue Dec 18 16:41:59 EST 2007


Well I trying to post process a particle system and thought a nice little
VOP SOP could do that. I wanted to drive the attributes from a LUT,
but i can't because it won't let me.

It's just a pain because I now have to make an otl. And more so because the
Globals VOP has all that already attached so you think it should work, and after
bashing your head on the desk for a bit realise it don't.

no worries, I'll just do a little attribute voodoo and trick it in to compliance.



----- "Ivan DeWolf" <ivan at martian-labs.com> wrote:
> also, why would you want to? if you're asking Houdini to solve some
> complex
> expression in an argument field of a custom VEX SOP, doesn't it make
> more sense
> to do that computation in your VEX code? (or VOP net, whatever) you
> have access
> to the same point attributes, and you're already creating code (or
> nets)...
> 
> having said that, however, VEX (and VOPs) seems unable to read int
> point
> attributes, and 2-dimensional float point attributes. ID is an int
> point
> attrib, and life is a 2-d float point attrib.... so I usually precede
> my VEX
> SOP with a point SOP and set $CR to $LIFE and $CG to $ID and access Cd
> in the
> SOP, or something similar.... a minor hassle, but worth noting...
> (unless this
> has changed in H9.?.???)
> 
> 
> Quoting Peter Bowmar <pbowmar at gmail.com>:
> 
> > No Houdini locals work in VEX/VOP nodes. You have to put it into
> the
> > VOPnet itself as a Parameter VOP to get it to import. This is how
> VEX
> > works. It's for speed, as local variables are relatively slow to
> > calculate whereas the pure VEX is very fast.
> > 
> > Cheers,
> > 
> > Peter B
> > 
> > On 18/12/2007, Andrew D Lyons <tstexture at gmail.com> wrote:
> > > Yeh - I hear you. Some Houdini locals work, and some don't from
> > > memory. I'm surprised $LIFE doesn't.
> > >
> > > Good $localVar and expression support in Vex OP UI parameters
> would be
> > > the icing on the vex OP cake IMHO. Often it's necessary to wrap
> vex
> > > OPs in a HDA subnet that handles all the attribCreate nonsense
> for
> > > artists, but then you end up with 2 ops for every purpose in your
> > > menus. One that does the raw vex number crunching and one that
> has
> > > high level bells and whistles for users. Often they are named in
> a
> > > similar way, and then people have to remember which OP is the
> decoy
> > > and which is the money (depending on how they look at it.)
> > >
> > > This brings me to another long-standing RFE - the ability to load
> a
> > > hda - and have it accessible - but yet not appear as clutter in
> your
> > > OPmenus. I thought that was going to be part of H9 - but I'm yet
> to
> > > see it. Anyone know what happened to that one?
> > >
> > > Cheers
> > >
> > >
> > >
> > > On 17/12/2007, Jerry Corda-Stanley
> <jerry at intelligentcreatures.com> wrote:
> > > > Well I created the VOP SOP in H9, and wanted to stick $LIFE in
> the
> > parameter
> > > > field of the VOP I created to change the colour.
> > > > I was trying to keep it neat with out messing about with
> attribute
> > creates
> > > > and so on.
> > > >
> > > >
> > > > ----- "Andrew D Lyons" <tstexture at gmail.com> wrote:
> > > > > In the SOP parameters or in the VOPnet itself?
> > > > >
> > > > > Traditionally there have been problems with putting complex
> > > > > expressions in the parms of a VEX OP. Often you have to
> override VEX
> > > > > parms by creating an attribute of the same name and type with
> an
> > > > > attribCreate SOP further up the chain. If you have a parameter
> VOP of
> > > > > the same name you generally pass things in that way.
> > > > >
> > > > > Cheers
> > > > >
> > > > > On 17/12/2007, Jerry Corda-Stanley
> <jerry at intelligentcreatures.com>
> > > > > wrote:
> > > > > > How do I get local varaibles such as $ID and $LIFE to be
> recognised
> > > > > in a VOP SOP?
> > > > > > I put together a SOP to futz around with stuff and it's
> complaining
> > > > > that the variables
> > > > > > are undefined. So how do I define them?
> > > > > > _______________________________________________
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> > > > > >
> > > > >
> > > > >
> > > > > --
> > > > > =======================================
> > > > > Andrew D Lyons | Digital Artist | http://www.tstex.com
> > > > > =======================================
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> > >
> > >
> > > --
> > > =======================================
> > > Andrew D Lyons | Digital Artist | http://www.tstex.com
> > > =======================================
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> 
> 
> -Ivan
> 
> ---------------------------------------------------------
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