The Maya Embedded Language (MEL) is a
scripting language
In computing, a script is a relatively short and simple set of instructions that typically automation, automate an otherwise manual process. The act of writing a script is called scripting. A scripting language or script language is a programming ...
used to simplify tasks in the
3D graphics
3D computer graphics, sometimes called CGI, 3D-CGI or three-dimensional computer graphics, are graphics that use a three-dimensional representation of geometric data (often Cartesian) that is stored in the computer for the purposes of perfor ...
software
Autodesk Maya
Autodesk Maya, commonly shortened to just Maya (; ), is a 3D computer graphics application that runs on Windows, macOS, and Linux, originally developed by Alias and currently owned and developed by Autodesk. It is used to create assets for inter ...
. Most tasks that can be achieved through Maya's
GUI can be achieved with MEL, as well as certain tasks that are not available from the GUI. MEL offers a method of speeding up complicated or repetitive tasks, as well as allowing users to redistribute a specific set of commands to others that may find it useful.
Design
MEL is syntactically similar to
Perl
Perl is a high-level, general-purpose, interpreted, dynamic programming language. Though Perl is not officially an acronym, there are various backronyms in use, including "Practical Extraction and Reporting Language".
Perl was developed ...
and
Tcl. It provides some memory management and dynamic array-allocation, and offers direct access to functions specific to Maya. The majority of standard Maya commands are default MEL scripts, saved in the Maya Program Files directory.
MEL is fairly limited compared to mainstream scripting languages. It is primarily a language meant to journal the Maya session, so it lacks many advanced features such as associative arrays.
Python was added to Maya as an alternative to MEL in Maya 8.5. Still MEL offers some advantages to Python:
* Discoverability of MEL is better since the built-in command echo server was created with MEL in mind.
* A lot of legacy code and inner working of Maya is in MEL form. This provides many insights into undocumented inner workings of Maya.
MEL is often criticized for its lack of programming features, and object orientation. In practice, however, MEL is used as a
metaprogramming
Metaprogramming is a computer programming technique in which computer programs have the ability to treat other programs as their data. It means that a program can be designed to read, generate, analyse, or transform other programs, and even modi ...
language where MEL just instructs Maya's node architecture to solve the problem. Since nodes form the actual computational core of Maya using a more robust readily apparent programming method would be a very inefficient approach. In many ways MEL complements the Maya API, with somewhat clear boundaries between allocated tasks. This makes MEL harder to learn and fully understand.
Uses
The tools designed using MEL scripts generally come under the following categories:
*Data I/O
*Motion capture data import
*Proprietary game data export
*Scene meta-data for production tracking
*Geometry creation and modification
*Custom primitives
*Third-party renderer specific data type (e.g., RenderMan sub-divisional surfaces)
*Modeling tools not offered in the base package
*Animation tools
*Muscle simulators
*Rigging and setting up controls
*Crowd AI behavior
*Lighting /rendering tools
*Automatic creation of common complex shader setups
*Pre- and post-render effects
*Making calls to third-party renderers
*Dynamics
*Custom particle behavior
*Simulated object emergent flocking and swarming
*Genetic algorithms
*Cloth simulation
*File and folder scene setup and maintenance
*User interface customization
*Custom character controls
*Removal of invalid Maya commands
*Custom UIs
Example
This is an example of a script which copies a selected object through its path:
// animated duplicates/instances script
proc animatedDuplication (int $rangeStart, int $rangeEnd, int $numOfDuplicates, int $duplicateOrInstance)
// Usage example:
// duplicate the current selection 5 times --
// evenly distributed between frame 1 and 240
animatedDuplication(1, 240, 5, 0);
Features
Maya also offers an expression language that is a super-set of MEL, and results in nodes that are executed as part of
Maya's dependency graph. Expressions are developed with Maya's
expression editor, and allow scripts to trigger while Maya evaluates the scene file at each change in time, to simulate complex behaviors or perform other useful tasks.
References
*
Mark R. Wilkins,
Chris Kazmier: "
MEL Scripting for Maya Animators". 2nd edition, Morgan Kaufmann 2005;
*
Pisca, Nicholas, "
YSYT - Maya MEL Basics for Designers". 1st edition, 0001d Publishing 2009;
External links
* {{official_website, http://www.autodesk.com/products/autodesk-maya/overview
MEL command reference (Maya 2013)MEL and Expressions - Autodesk Maya 2015 HelpMel WikiUseful Scripts for MayaCGSociety - Maya Programming forumCGSociety - 'MEL scripts' threadCGSociety - 'Maya UI Building' threadMEL Scripting Tutorials for Maya - CreativeCrashMEL video tutorials - lynda.comDigital Tutors search - MELMEL - maya rigging wikiMel Scripting - RobTheBloke Scripting languages