We've Moved

The blog has been retired - it's up for legacy reasons, but these days I'm blogging at blog.theodox.com. All of the content from this site has been replicated there, and that's where all of the new content will be posted. The new feed is here

Tuesday, October 27, 2015

Grrrr..... Maya!!!

Some kinds of pain are just occasional: you stub your toe or bump your head, ouch, and then its over. Other kinds of pain aren't as sharp or as sudden... but they're chronic.  That persistent twinge in your lower back may not hurt as much as a twisted ankle - but it's going to be there forever (at least unless you get in to power Yoga, or so my wife claims).
 Maya is old enough to have a few of those chronic pains, and I just ran in to one which -- once we debugged it and figured it out -- I realized has been a constant irritant for at least the last decade and if my creaky old memory does not lie was a distinct pain in the butt as long ago as 2002. In another context I might even have been able to diagnose it but instead we spent a ton of time and energy working around an unexpected behavior which is, in fact, purely standard Maya. It's stupid Maya, but it's standard too.  Maya, alas, is double plus ungood about mixing per-face and per-object material assignments. So, I figured I'd document this here for future sufferers: it might not ease the pain much, but at least you'll know you're not crazy.
 The basic problem is that assigning materials to faces and to objects use slightly different mechanisms. If you check your hypergraph you'll see that per-face assignments connect to their shadingGroup nodes through the compInstObjectGroups[] attribute while object-level assigmemts go through the similar-but-not-identical instObjectGroups attribute (if you're looking for these in the docs, the component cone is inherited from the geometryShape class and the object version comes from dagNode).
 As long as you're working with one object at a time this isn't a problem. However, if you're duplicating or copy-pasting nodes, there's a gotcha:  If you ever try to merge meshes which have a mix of per-face and per-object assignments, Maya will magically "remember" old per-face assigments in the combined mesh.  If you're a masochist, here's the repro:

  1. create a object, give it a couple of different materials on different faces
  2. duplicate it a couple of times
  3. assign a per-object material to the duplicates, overriding the original per-face assignments
  4. combine all the meshes.
  5. Et voƮla! The cloned meshes revert to their original assignments

What appears to happen is that those compInstObjectGroups connections are driven by hidden groupID nodes which don't get deleted when the per-face assignments are overridden by the per-object ones in step (3) .  They stick around even though they aren't being used, and when the mesh is combined they step right back into their original roles.

If you're doing this interactively it's an annoyance. If you're got tools that do things like auto-combine meshes to cut down on transform load in your game.... well, it's a source of some surprising bugs and equally surprising bursts of profanity.  But at least it'ss predictable.

The workaround:  Before doing any mesh combination, delete the history and something harmless to this history of the meshes you're about to combine. (I use a triangulate step, since this happens only at export time) . That kills the rogue <code>groupID</code> nodes and keeps the combined mesh looking the way you intended.

Sheesh. What a way to make a living.

Tuesday, October 6, 2015

Charcoal - it's smokin'!

When you’re shopping around for something new – whether it’s a cool new piece of software or just a kitchen gadget – it’s not uncommon to tell yourself, “man, I wish I had thought of that.” But what’s really impressive is when you see a polished product and you say to yourself Dammnit, I absolutely thought of that!, or I’ve been wanting this exact thing for years!. It’s a rare thrill when you stumble across something that seems as if it were a gift from some future self, come back to give you exactly what you wanted in a way that only you, yourself could.
One of my coworkers found one of those little somethings the other day - a product that will make pretty much any TA go feel like Christmas came a little early.
The Charcoal Editor from Chris Zurbrigg is a slick, polished replacement for Maya’s script editor. It’s a plugin (available for Maya on Mac, Windows and Linux) that offers many of the features of a slick Python IDE right inside of Maya. Some of the key highlights include
  • Syntax highlighing
  • Autcomplete (including your own code and also the entire Maya cmds api)
  • Smart indent and dedent
  • Bracket matching
but the feature that will sell most Maya veterans instantly is the fact you can execute lines or scripts without the familiar Select > Enter that has deleted countless lines of your test code down the ages.

Charcoal Editor Overview from Chris Zurbrigg on Vimeo.

That one feature alone would probably be worth the price for most people who do a lot of scripting. But the whole package is thoughtfully put together in a way that clearly says the author wrote a tool for himself – and that he shares a lot of the frustrations that have driven you and I bonkers for the last 18 years of Maya history. A great example is the addition of quick help for Maya commands: if you (like me) can never remember the difference between the flags for listConnections and those for listRelatives, Charcaol allows you to pop up a quick in-window help view or to open the relevant documentation in a browser: a welcome alternative to the maddening ritual of entering “cmds.whatever” into Chrome and being directed to the Maya 2011 Japanese docs by the mysterious imps of the internet.
In general, Charcoal shows a lot of attention to the nuances of scripting work. For example, it allows you to quickly toggle layouts: Charcoal allows you to quickly flip back and forth between the usual split view and a full panel of either script or history, so you don’t have to give up coding space to see your printouts or vice-versa. Likewise, you can set font sizes and color schemes for the scripting panel and the history panel separately – a big help if you want to save space on your printouts or if (like me) your eyes are going and you need to bump up the font size for coding. The history panel even supports highlighting – separating errors and warnings clearly from regular printouts, for example. All in all it’s a collection of small touches that offers a much-appreciated sense that the program has your back and that the author has wrestled with many of the same irritations you’ve had.
The product also ventures into territory that’s useally associated with full-fledged IDEs. It particular it offers an “outline view” which displays the classes and functions in the current scope - a big help for navigating around in a longish file, as well as a handy way to remember what you’re working with. There’s also a “project view” which displays all of the scripts in a project folder tree – more or less the same as the project views in Sublime Text or Atom (two other scripter-friendly editors you should check out if you’ve never seen them.)
These IDE features will be very helpful for folks who’ve been soldiering on with nothing but the Maya script editor and Notepad. If you’re already using an IDE like PyCharm, Wing, or PTVS they may not be quite enough to wean you out of your fancy environment – particularly if you’r gotten used to using a real debugger instead of littering your code with print statements. Charcoal’s project features are functional but – given the nature of the task and the audience – are not as fancy as the equivalent features in big budget development environments. If you really prize the ablity to inifitely noodle on color themes, or a built-in style guide, you may find yourself wandering back to one of the bigger packages. That’s not a knock on Charcoal, though – it’s just a reminder that it’s a specialist tool for Maya users and not a general-purpose project management powerhouse.
For myself, I plan on sticking with PyCharm for long coding sessions (btw, PyCharm fans, you’ll be incredibly pleased to hear that Charcoal allows cut and paste directly from PyCharm, unlike Maya’s wonky script editor. Whoop-de-doo!) However Charcoal more than justifies itself as a replacement for the vanilla script editor with a lot of juicy productivity features. I’ve already gotten a lot of productivity bounce by using MayaCharm to bypass the Maya script editor whenever possible – but I still spend quite a lot of time in the clunky old Maya pane nonetheless. I’ve got high hopes that Charcoal will save precious brain power for real problems and allow me to focus more on doing my job and less on frantically hitting Undo after my last attempt to execute a line accidentally erased an hour’s work.
Charcoal offers a free, non-saving demo; an individual license is $49 US (site licenses are available but you’ll have to negotiate them with the author).