Hi.
MyOp* theFirst = dynamic_cast<MyOp*>(firstOp());
if(theFirst && theFirst->m_firstTime && !f.makeKnobs() ) {
theFirst->m_firstTime = false;
call_my_function_here();
}
I think there is no need in knob, if you use DO_NOT_SAVE.
2011/11/1 Ivan Busquets <[email protected]>:
> Hi all,
>
> I've recently come across the following problem.
>
> Let's say I've got something that I want to run during the first knobs()
> pass after the makeKnobs() pass. So, in knobs(), I have something like this:
>
> if (!f.makeKnobs() && m_firstTime)
> {
> m_firstTime = false; // m_firstTime is a member variable that's
> initialized to "true" in the constructor
> call_my_function_here(); // the function sets some knob values, btw
> }
>
>
> This used to work fine for me in 6.2. In 6.3, myfunction gets called
> multiple times for each node, particularly when the node has animated knobs.
> I "suppose" this comes from the node spawning multiple Ops, but I'm confused
> because this didn't seem to happen in 6.2? I've seen that 6.3 seems to split
> Ops more often (when they're upstream of a Transform with motionblur turned
> on, for example), but I'm not sure whether that's an intended change or a
> misbehaviour...
>
> In any case, the function I call in there is expensive, so it is a big deal
> if it's called multiple times. Is there a better way to approach this?
> Basically what I want is to call something, only once, as early as possible
> (or in the earliest stage where I can set knob values).
>
> As a workaround, I am now resorting to storing m_firstTime in a hidden knob
> with both the EARLY_STORE flag (so that if my Node spawns multiple ops
> they'll get the right value for m_firstTime), and the DO_NOT_SAVE flag (to
> force m_firstTime back to "true" when the node is created, reopened, or copy
> pasted).
>
> So, I now have something like this:
>
> void knobs(Knob_Callback f)
> {
> [....]
>
> Bool_knob(f, &m_firstTime, "first");
> SetFlags(f, Knob::EARLY_STORE | Knob::INVISIBLE | Knob::DO_NOT_WRITE);
>
> if (!f.makeKnobs() && m_firstTime)
> {
> knob("first"->set_value(false);
> call_my_function_here();
> }
> }
>
>
> This seems to work (as in, that portion of knobs() seems to be called just
> once now), but I'd like to know if there's a more elegant way to do this, or
> a better strategy altogether.
>
> Thanks,
> Ivan
>
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>
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