Notes - Nodes & Mash – Maya

Here are some learning notes on creating a  plug-in for Maya, creating relationships with expressions and Maya's new python node. These are notes for me but perhaps others may stumble upon them and find them to be of interest. I'll probably change and grow this page as I learn a little more.

1. Notes and links on how to create a Maya plug-in

Autodesk have an example Python Math Node. Here are my notes:

• API module: import maya.openMaya
• Proxy class access: import maya.openMayaMPx
• Access to math module: import math
  
• Variable for node name:  kPluginNodeTypeName = "nodeNameNode"
• ID number for Node:        nodeNameNodeId = OpenMaya.MTypeId(0x00001)
• Define subclass of existing class: class nodeName(OpenMayaMPx.MPxNode)
• input = OpenMaya.MObject()
• output = OpenMaya.MObject()
• Override constructor using base: OpenMayaMPx.MPxNode.__init__(self)
• plug = current input: def compute(self,plug,dataBlock):
• Compute math example: result = math.sin( inputFloat )
• Recompute plug and flag as clean: dataBlock.setClean( plug )
• Maya pointer: return OpenMayaMPx.asMPxPtr( sineNode() )
• Initialize method - input and output: nodeInitializer():
• Add attribute here (ex- frequency or or amplitude): input = nAttr.create( "input", "in", ####)
• Causes compute method to re-calculate - sets relationship: sineNode.attributeAffects( sineNode.input, sineNode.output )
• Plug-in registration - Node Name/ID/Create Method/Initialize Method/Node Type: mplugin.registerNode( kPluginNodeTypeName, sineNodeId, nodeCreator, nodeInitializer )
• De-register plug-in: mplugin.deregisterNode( sineNodeId)

Understanding this we can now turn these python math functions into Maya nodes:

2. Some links to various resources:

• Creating a simple Maya node with python - Three render Monkeys
• Python Scripting for Maya artists 2.0 - Chad Vernon
• The Maya Autodesk Help Documentation
• Autodesk uses the "Simplified Wrapper and Interface Generator (SWIG) to create
• bindings between c++ and Python" - see: Practical Maya Programming with Python
• Complete Maya Programming - Book by David. A. D. Gould
• How did Python become a Data Science Powerhouse?

Classes:

• Wrappers - math classes - m -(Quaternion, matrix, vector, points, vectors etc)
• MObjects - data encapsulation (meshes, skin clustter nodes, curves  etc).
• Functions Sets - mfn  - (access and manipulate data)
• Proxy Class - mpx - - (abstractions - create new object types - inheritance)

For memory intensive process plug-ins need to be complied in c++. Here are some links:

• Createing your first Maya Plug-in in Visual Studio
• A unified approach to compiling and maintaining Maya plug-ins across all platforms - in CMAKE

3. Example: Testing cosine node works.

3. A Mel expression that does the exact same thing. A little bit less work :)

Two very simple expressions that create tangent circles (also known as kissing circles).

Nodes and expressions can build almost any kind of relationship we want.

4. Mash Python node (Maya)

Python Node Test with controllers piped in as variables - Expression: (cos(t) + cos(6t)/2 + sin(14t)/3, sin(t) + sin(6t)/2 + cos(14t)/3) - (see article "Creating Art with Mathematics"). Perhaps usful patterns for stone placement or tiles of some sort.