Yes, this is not reliable. My example was very specific in not doing
that, and in fetching values out of knob()->get_value() directly, which
will work.
On Thu, 2011-06-16 at 10:03 -0700, Nathan Rusch wrote:
> Ah, that did the trick... mostly.
>
> Unfortunately, the knob updating seems to be a little lazy. However, this
> may be a result of some bad order-of-operations on my part.
>
> Currently I'm using a private bool pretty much directly as the feedback
> knob's value. This bool is being set in _validate (skeleton code is included
> below). The bool is used in request and engine to determine which input to
> use, and that part of things seems to be working fine (which makes me think
> it should be safe to use as the feedback value). However, the knob seems to
> be failing to update fairly randomly. Sometimes it's one change behind, and
> sometimes it just doesn't do anything.
>
> ----------------------------------------------------------------------------------
>
> class HashSwitch : public NoIop, public ArrayKnobI::ValueProvider
> {
> bool m_useMeta;
> int m_which;
>
> public:
> HashSwitch(Node* node) : NoIop(node
> {
> inputs(2);
> m_useMeta = false;
> m_which = 0;
> }
>
> void knobs(Knob_Callback f)
> {
> Knob* wch = Int_knob(f, &m_which, "which")
> wch->set_flag(Knob::DO_NOT_WRITE);
> if (f.makeKnobs())
> {
> dynamic_cast<ArrayKnobI*>(wch)->setValueProvider(this);
> }
> }
>
> std::vector<double> provideValues(const ArrayKnobI*, const
> OutputContext& oc) const
> {
> std::vector<double> values;
> values.push_back(m_useMeta);
> return values;
> }
>
> void _validate(bool for_real)
> {
> // Test metadata from one input against hash generated from other
> input
> // then do copy_info() on one input or the other and set m_useMeta
> to true/false
> // based on whether the hashes match.
>
> // Is this bool unreliable as a feedback value?
> }
> }
> ----------------------------------------------------------------------------------
>
> Any thoughts?
>
> Thanks for your patience on this one,
>
> -Nathan
>
>
>
> -----Original Message-----
> From: Abigail Brady
> Sent: Thursday, June 16, 2011 2:25 AM
> To: Nuke plug-in development discussion
> Subject: Re: [Nuke-dev] Using knob as a feedback device
>
> Oh, sorry, I think that's a new thing in 6.3. if f.makeKnobs()
> dynamic_cast the Knob to ArrayKnobI and call setValueProvider() on that,
> I believe is the actual answer.
>
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