From what I can tell, 'pw' is an array of 'Channel's, probably a knob storage var (meant to represent the channels picked as P-World).
In your foreach, 'z' will be a Channel. As for ChannnelSet vs. ChannelMask, I'm not in front of the NDK headers right now so I could be misremembering, but I believe one of them is slowly being phased out in favor of the other. I think ChannelMask is on the way out, but needs to be kept around for the time being for source compatibility. -Nathan On May 17, 2012, at 7:32 AM, "Steven Booth" <sbo...@legend3d.com> wrote: > Jordan, > > Before I deal with this, one question. What is your definition of 'pw', > because it can't be a 'ChannelSet'. Is it an array of ChannelSet's? An > array of 'Channel's? > > Steve > > -----Original Message----- > From: nuke-dev-boun...@support.thefoundry.co.uk > [mailto:nuke-dev-boun...@support.thefoundry.co.uk] On Behalf Of Jordan Olson > Sent: Wednesday, May 16, 2012 4:01 PM > To: Nuke plug-in development discussion > Subject: Re: [Nuke-dev] Inexperienced NDK simple question on pixelIop channels > > Hey Steve, > thanks heaps for your writeup! To give you an idea of my background, I've > been comping and python scripting Nuke for a few years, but only recently > attended a class for C++ and am diving into the NDK. So I'm still fairly new > to the NDK and C++ in general. > > > When you explained that 'channels' may only contain channels being requested > of the node by nodes downstream, that was a pretty revolutionary perspective > change for me! > > Though adding the if(ch_pw) doesn't prevent the node from crashing, I think > we're getting somewhere. > > A couple questions; > > -- When running foreach(z, channels); I presume based on your explanation > that "z" does not represent an integer? for some reason I was thinking it > represented an integer (which is why I used it to index pw[z])- because I > assumed "z" would be an integer range from 0-3. > If I understand you right, "z" could actually be a "Depth.Z" channel and not > an integer like 1. So unless the point world knob contains Depth.Z (which it > wouldn't) this would always be NULL. > > -- How are the ChannelMask and ChannelSet classes different from each other? > (and even with the class method PointSample:in_channels() ChannelSet& is > defined as "mask" which I find confusing). > > I'm re-reading the documentation again- although I'm hacking together code > from alot of different source examples, I still don't really get how to bring > in a specified layer and access those channels.. > > Cheers, > Jordan > > > > On Thu, May 17, 2012 at 3:43 AM, Steven Booth <sbo...@legend3d.com> wrote: >> Jordan, >> >> >> >> I think I see what might be the problem here. You define ch_'pw' like >> this >> >> >> >> Channel ch_pw = pw[z]; >> >> >> >> And then use it like this: >> >> >> >> const float* pw_ptr = in[ch_pw] + x; >> >> >> >> Here's the secret: You have absolutely no guarantee what 'channels' >> contains. 'channels' are the channels *being requested of you by the >> downstream node*. If you hook a shuffle up to your node (Op), and >> shuffle Depth.Z into R, then 'Depth.Z' is going to be placed into the >> 'channels' >> ChannelSet passed to your _engine call. >> >> >> >> If, then, your 'point world' ChannelSet isn't requested, or isn't >> fully requested, then pw[z] is going to eventually return NULL. That >> makes 'ch_pw' NULL, and when you do the 'in[ch_pw]', *that* is going >> to be null, which makes pw_ptr NULL, which kind of makes: >> >> >> >> float a = *pw_ptr++; >> >> >> >> somewhat (well. more like 'really') invalid. >> >> >> >> What you always need to do is make sure the channel you're processing >> is actually being asked for. that your channel references are non-null so: >> >> >> >> Channel ch_pw = pw[z]; >> >> If (ch_pw) { >> >> . code that uses 'ch_pw' >> >> } >> >> >> >> So, the inner code is only used if 'ch_pw' is not null. >> >> >> >> Hope that helps >> >> >> >> Steve >> >> >> >> >> >> >> >> >> >> -----Original Message----- >> From: nuke-dev-boun...@support.thefoundry.co.uk >> [mailto:nuke-dev-boun...@support.thefoundry.co.uk] On Behalf Of Jordan >> Olson >> Sent: Tuesday, May 15, 2012 5:56 PM >> To: Nuke plug-in development discussion >> Subject: [Nuke-dev] Inexperienced NDK simple question on pixelIop >> channels >> >> >> >> hey fellow Nuke developers! >> >> I'm writing a pixelIop node at the moment, and having difficulty >> figuring out some code. >> >> >> >> I have an extra knob for "Point World" channelset, and to test it, I'm >> trying to copy the pixel values from this set into the standard >> channels specified by the user. (default RGBA). >> >> However it's crashing, and I think I need to implement something like >> the following example taken from the IDistort Iop code: >> >> >> >> >> >> // missing channels will crash, use black instead: >> >> Channel uu = uv[0]; >> >> Channel vv = uv[1]; >> >> if (!intersect(tile.channels(), uu)) >> >> uu = Chan_Black; >> >> if (!intersect(tile.channels(), vv)) >> >> vv = Chan_Black; >> >> >> >> >> >> However this ^ is from an Iop node, and I'm having a crash on a >> PixelIop. Is there a similar function I could implement on my pixel operator? >> >> Here is my code below, slightly simplified for readability. >> >> >> >> >> >> >> >> ............ >> >> >> >> void PointSample::_validate(bool for_real){ >> >> copy_info(); >> >> set_out_channels(Mask_All); >> >> } >> >> >> >> void PointSample::in_channels(int input, ChannelSet& mask) const { >> >> mask += (pw[0]); >> >> mask += (pw[1]); >> >> mask += (pw[2]); >> >> } >> >> >> >> void PointSample::pixel_engine(const Row& in, int y, int x, int r, >> ChannelMask channels, Row& out) { >> >> foreach (z, channels) >> >> { >> >> const float* inptr = in[z]+x; >> >> const float* END = inptr+(r-x); >> >> >> >> Channel ch_pw = pw[z]; >> >> // This doesn't compile because the Pixel Iop has no >> tile functionality >> >> /* >> >> if (!intersect(tile.channels(), >> ch_pw)) >> >> ch_pw = >> Chan_Black; >> >> */ >> >> >> >> const float* pw_ptr = in[ch_pw] + x; >> >> float* outptr = out.writable(z)+x; >> >> >> >> while (pw_ptr < END) >> >> { >> >> float >> a = *pw_ptr++; >> >> >> *outptr++ = a; >> >> } >> >> >> >> } >> >> } >> >> >> >> ............ >> >> >> >> >> >> cheers if you could point out why this is crashing! >> >> Jordan >> >> _______________________________________________ >> >> Nuke-dev mailing list >> >> Nuke-dev@support.thefoundry.co.uk, http://forums.thefoundry.co.uk/ >> http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-dev >> >> (CONFIDENTIALITY NOTICE: The information contained in this email may >> be confidential and/or privileged. 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Thank You.) >> >> >> _______________________________________________ >> Nuke-dev mailing list >> Nuke-dev@support.thefoundry.co.uk, http://forums.thefoundry.co.uk/ >> http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-dev >> > _______________________________________________ > Nuke-dev mailing list > Nuke-dev@support.thefoundry.co.uk, http://forums.thefoundry.co.uk/ > http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-dev > (CONFIDENTIALITY NOTICE: The information contained in this email may be > confidential and/or privileged. This email is intended to be reviewed by only > the individual or organization named above. If you are not the intended > recipient, or an authorized representative of the intended recipient, you are > hereby notified that any review, dissemination or copying of this email, or > the information contained herein is strictly prohibited. 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