I found an awesome article today from last year's GDC session by Kristion Middlemiss. I want to share it with you. It is really useful for Maya Python beginners.
10)
Not Understanding the
Difference between Python Script and Python API
Maya has four programming interfaces, two
of which are using the Python language. It’s important to know the distinction
between the terminology of Python Script and the Python API, because they each
access different functionality within Maya (with very little overlap). The
other two interfaces are Maya Embedded Language (MEL) and the C++ API.
9) Python Plug-in Disclosure
You cannot hide your Python API code from
users! If you’re a games developer looking to create Python plug-ins in-house
and not worried about protecting your code, then feel free to code away. But it
you want to protect, or commercialize and sell your hard work, you should
consider using C++ to create your plug-ins.
8) Must use Autodesk Specific Version of Qt
for Building PyQt
Building PyQt to work with Maya is a three
step process. First you need to compile Qt using the Autodesk's Modified Qt
Source Code (new for 2012) that is located on the Autodesk.com site. Then you
need to compile SIP (generates Python bindings for C++) against your built Qt
libraries. Last, you need to compile PyQt against your built SIP libraries.
Check the website for the correct versions or you could have some difficulties
down the road in your tools.
7) Awareness of Potential Python API
Performance Penalties
In certain situations when computation
involves complex or many API calls, the Python API may take a performance
penalty compared to the C++ API. This is because the Python API sits on top of
the C++ API. This results in an extra level of conversion through C++ and as
well as Python is an interpreted language which is slower by nature. For
example if you are thinking of doing a Python API shader, C++ will be the
better choice, but for most other tasks Python is perfect!
6) Working with Multiple Versions of Maya
Equals Multiple Versions of Python
If you are working on multiple versions of
Maya, then you need to keep in mind that you will need to have multiple version
of Python. Also if you are using PyQt, multiple versions of PyQt will need to
be installed on your computer. As nice as it would be to use the same version
of Python and PyQt for every version of Maya, it’s just not realistic as things
are always improving in the Python and PyQt releases. Keep yourself educated in
the Maya documentation for the versions that are used in each major release,
and on which platform.
5) Your Python API Code is not Working, and
you cannot find the Problem
When working with the Python API, like all
humans, you will have errors or code you want to debug; but how the heck do you
debug it? Unfortunately, there are no out-of-the-box tools in Maya, but there
are some good solutions available. Cyrille Fauvel from Autodesk has integrated
a Maya Python debugger into the Eclipse IDE. The details are available on
Autodesk.com, at the Maya Developer Center page. Dean Edmonds also from
Autodesk has integrated the PDB debugger into the Script Editor within Maya by
overriding the stdin and stout functions. Also, if you Google “Python in Maya”
group you will see other solutions.
4) Knowing when and how to Use MScriptUtil
Class
Many of the API methods in Maya require
that one or more of their parameters be passed as pointers or references
(return values can be pointers or references as well). Because Python does not
have the concept of references or pointers, you will need the utility class
called MScriptUtil for working with those pointers and references in Python.
MScriptUtil bridges this gap between Python and its underlying C++ API. When
you see the characters * or & in the documentation for simple data types
like integers and floats, think MScriptUtil!
3) The Reference Documentation is written
for C++, but you are Using Python
If you do not know C++, at first glance the
reference documentation will be very confusing!
But don’t worry; just put your eye blinders on to certain things when
reading it. Because Python is a more simplified language than C++ (but none the
less powerful), there are certain components in the documentation you can
ignore. For example the class MString and MStringArray are not available in
Python and instead you will work with strings as they are in native Python.
Another example is that there is no MStatus class in Python and instead you
will use standard Python error checking (try, except, catch). Try to think of
this as having a mini translator going on in your brain, you see MStatus, so
you just ignore it!
2) Trying to live in a Bubble and Teach
Yourself Everything
There is no possible way to memorize or
learn every single Maya API class, so don’t be shy to use the resources
available. As they say “Be Resourceful” and learn from others successes,
mistakes and questions. Maya has been around for over ten years, and there is
lots of API information out there (www.autodesk.com/developmaya). Also, you can
check out the new book “Maya Python for Games and Film: A Complete Reference
for Maya Python and the Maya Python API” by Adam
1) Mechtley and Ryan
Trowbridge.
Not Fully Grasping the Maya Architecture
and How the Python API Leverages It
If you don’t completely understanding the
Maya architecture, command engine and the Dependency Graph, you will run into
trouble as your tools get more complex. Take the time to learn these components
as they are very different than any other animation product. Because of this
complexity, it makes Maya more flexible and powerful than any other product.
Check out the free Maya Python API webcast recording located here
(www.autodesk.com/developmaya)
