[Sidefx-houdini-list] I3d Opacity

Pablo Giménez pablogipi at gmail.com
Mon Aug 7 07:02:35 EDT 2006


On 8/7/06, Peter Bowmar <pbowmar at gmail.com> wrote:
> Hey Pablo,
>    Actually, SOPs not supported local variable in all SOPs is due to
> SOPs being written first, long before the concept of having local
> variables existed. The POPs engine was written specifically with local
> variables in mind, the SOPs were "retro-fitted" to support them, but
> as you notice, not all SOPs use them. This is mostly due to those SOPs
> not having the work done on them. Some SOPs just don't make sense to
> have local variables but generally the ones that do make sense, do
> have the ability to use them.
Thanks Peter.
So then do you prefer to have local variables instead of global?
>
> Cheers,
>
> Peter B
>
> On 07/08/06, Pablo Giménez <pablogipi at gmail.com> wrote:
> > Hi Andrew, thanks for your complete reply.
> > Only to add my 2 cents to this discussion, I think that the only
> > reason to use Local variables instead of global variables in context
> > is memory.
> > The only thing, I think, that Andrew firget to say is why you can't
> > access to some variables in some circustances.
> > In Houdini there are some global variable, like $F, $FF, $FEND, $T, etc ...
> > But the variables that map attributes, regardless the context, are
> > always local, this means that are only availablr if the operator
> > enables it.
> > This problems is very noticiable in SOP context where always you can
> > find the problem to not be able to acces easily to an attribute
> > because the SOP you are using doesn't crate the local variable, then
> > you have two options:
> > - Use the point() expression: horrible and you need to have access to
> > the $PT variable.
> > - Use Attribute Create SOP: this actually creates global variables
> > instead of local variables.
> > In POP context is the same problem, the onlyu difference is that
> > almost all (ALMOST) POP operators creates the needed local variables,
> > but for example if you create your own VEX POP operator, because the
> > variables are local, you can't access to the $LIFE, $AGE, $V, etc ...
> > you have to use an Attribute POP  prior to your VEX POP to create
> > another global varible that maps to your needed attribute.
> > So, like Andrew have said, we have the problem to not be able to
> > access easily tou our date everytime, everywhere.
> > The only two reasons because I think SESI do this in this way are:
> > - Memory: to have all the attributes mapped to global variables needs
> > memory all the time to mantein these.
> > - The want to avois to have so much global variables.
> >
> > Finally I am agree with andrew, much of the time we want to have an
> > easy access to our data so I think that to have automatically global
> > variables to all of our attributes will be solution.
> >
> >
> >
> > --
> >
> > Un saludo
> > Best Regards
> > Pablo Giménez
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-- 

Un saludo
Best Regards
Pablo Giménez



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