maya programming for 3d graphics

Maya Programmingfor 3D Graphics

Wanho Choi

Last Update: 2011.9.8 http://wanochoi.com

Maya Programming for 3D Graphics http://wanochoi.com

What to do with Maya Programming

Development of our own in-house plug-in

Visualization of our demonstration


Commercial Maya Plug-ins

cMuscle

Qualoth

FXHair

Syflex

Blast Code

http://www.kocca.or.kr/ctnews/kor/SITE/data/img_dir/2005/07/06/200507060033.avi

http://www.syflex.biz/clnt/sylene1.mov

http://www.syflex.biz/clnt/sylene2.mov


Unfortunately …

There are a few references about Maya programming.

Among them, the first and most important thing is..

Maya Help file ( Help > Maya Help )

Always keep it at hand and consult with it!

However, it‟s not kind for beginners.


Books of Recommendation

Maya MEL programming


Books of Recommendation

Maya API programming


Some Codes Provided by Maya Itself

[Maya installed path]\devkit\plug-ins.


Introduction

to

Maya


Maya in Films

Ice Age, Lord of the Rings, Final Fantasy, Star Wars Episode, The Mummy,

Signs, Artificial Intelligence, Perfect Storm, Monster Inc., Stuart Little,

Spider-Man, Hollow Man, Blade, Harry Potter, Gladiator, Matrix, etc.


A Brief Introduction to Maya

One of the greatest and most complex computer program ever made

First released in 1998

Commercial total solution for 3D animation & visual effects

Modeling

Texturing

Animation

Rendering

Dynamics (rigid body, particles, fluids, etc.)

Maya is everywhere, especially in game, film and animation.

Rumor has it that

Implemented by over 200 PhDs.

Too big s.t. no one knows it entirely well.

Maya expert = Artist + Computer Scientist


Maya Version

Maya 1.0 (1998) Maya 1.5 (1998)

Maya 2.0 (1999) Maya 2.5 (1999)

Maya 3.0 (2000) Maya 3.5 (2001)

Maya 4.0 (2001) Maya 4.5 (2002)

Maya 5.0 (2003) Maya 5.5 (2003)

Maya 6.0 (2004) Maya 6.5 (2005)

Maya 7.0 (2005)

Maya 8.0 (2006)

Maya 8.5 (2007)

Maya 2008 (2007)

Maya 2009 (2008)

Maya 2010 (2009)

Maya 2011 (2010)


About Vendor

Alias Research, 1983

Wavefront Technologies, 1984

Alias|Wavefront under SGI, 1995

Alias@, 2003

Integrated into Autodesk, 2006


Other 3D Tools

Softimage | XSI

3D Studio Max

LightWave 3D

Cinema 4D

Houdini

Blender

etc.

http://tirad.com/tutorials/lw3d.htm

http://tirad.com/tutorials/c4d.htm


Maya as a 3D Animation Package

Maya has many features as default.


Maya Architecture

Maya := MELs + MLLs

MLL = DLL(Dynamic Link Library) in Maya

(.mll for Windows, .so for Linux)

GUI

command (MEL)

node (MLL)


Two Main Interfaces between User and Maya

GUI (Graphical User Interface)

Menus, dialog boxes, buttons, etc.

Most artists complete their work in Maya by using GUI.

Easy to use, but hard to extend Maya functionalities

Programming interface (Plug-in)

A small program to be added into Maya

Additional functionalities to Maya


Why Programming Interface?

Maya is very powerful tool, but cannot do everything.

Programming interface is needed.

You can “bend” Maya in your own direction.

Develop your own features using programming interface!

Automate and simplify tasks

Advanced macros and your own GUI

Add new features that are not incorporated

New file formats, object types and behaviors

New dynamics and animation components

Two programming interfaces

MEL script

C++ API


MEL or C++?

Two possible options for programming Maya

(Recently, you can also use Python.)

They are not mutually exclusive.

They are complementary each other.

There are some features available in one, but not in the other.

Creation of a new type of node : API

Creation of a new GUI : MEL

Some problems can be solved only by a combination of the two.

When the C++ programming interface is used, it is typically for specific

functionality that can‟t be found in the MEL interface.


MEL Script

MEL : Maya Embedded Language

Interpreted language

It can be executed immediately without compile & link.

Powerful

It provides all Maya‟s built-in functionality.

You can create new functionality by combining them.

Similar to pseudo code

It can be easy to read and written quickly.

It can result in subtle bugs which may be hard to find.


C++ API

API : Application Programmer Interface

Machine language (C++)

It is better performance than MEL. (approximately x10 faster)

C++ libraries

Enormous classes, but designed in a consistent manner

Most powerful means of extending Maya

It provides low level access to Maya.


Class Name Prefixes

M

MPx

MIt

MFn

Prefix

Maya class

Proxy object

Iterator class

Function set

Logical Grouping

MObject, MPoint, M3dView

MPxNode

MItDag, MItMeshEdge

MFnMesh, MFnDagNode

Examples


Dependency Graph Node Plug-ins

Twelve parent classes for dependency graph node plug-ins

MPxNode

MPxLocatorNode

MPxIkSolverNode

MPxDeformerNode

MPxFieldNode

MPxEmitterNode

MPxSpringNode

MPxManipContainer

MPxSurfaceShape

MPxObjectSet

MPxTransform

MPxHwShaderNode

You can subclass new nodes from these!


Brief

Exploration

into

Maya


Script Editor

Window > General Editors > Script Editor


Make a Cube

polyCube; [crtl+enter]


Hypergraph

Windows > Hypergraph


Check Node Type

nodeType pCube1; [crtl+enter]

nodeType pCubeShape1; [crtl+enter]

Transform

Node

Shape

Node


Check Attributes

listAttr pCube1; [crtl+enter]


Check Attributes

listAttr time1; [crtl+enter]

nodeType time1; [crtl+enter]


Connect Attributes

connectAttr time1.outTime pCube1.tx; [crtl+enter]


Hypergraph

Windows > Hypergraph


Result

Press


About

Maya

Node


Node-base Architecture

DAG node

DG node

time1 timeToUnitConversion1 transform

transform

shape

DG nodes

DAG nodesnode

input output


DAG (Directed Acyclic Graph)

DAG path

The complete path to a given node in DAG

You can get from the root node to the specific node by traveling down

through the intervening nodes in the tree.

DAG path for rightArmShape

: |head|toroso|rightArm|rightArmShape

head

headShape

torso

torsoShape

leftArm

leftArmShape

rightArm

rightArmShape


DAG Node

DAG nodes form parent-child relationship (hierarchy)

Transform node-shape node

DAG nodes are in DG - they are DG nodes

Some DAG nodes connect to non-DAG DG nodes

Some DAG nodes may not be connected to any non-DAG nodes.

Maya shows either DAG hierarchy or connected DG nodes,

not both simultaneously.


Shape Node

All shape nodes must have a parent transform node.

Meshes

NURBS curves and surfaces

Springs

Camera

Lights

Particles

Etc.


Transform Node

Shape node can’t exist without a transform node.

Shape node holds the data.

Transform node holds translation, rotation, scale, etc.

Transform node transforms from objects space to world space.

nurbsSphere1

nurbsSphereShape1


DG (Dependency Graph)

Data flow model

Data manipulated by series of operations

Pipeline

Push-pull model

DG(Dependency Graph) - heart of Maya

Data and operations represented as nodes

Network of nodes to perform task

Add functionality by defining new node


DG Node Mechanism

The fundamental building blocks of Maya Main purpose is to store data and modify it in some way.

Attributes - properties of a node Particular properties of a node Input/output of a node

Compute() A function to produce one or more output attributes from one or more input

attributes

When an attribute changes, recomputation propagates through the graph until all affected values have been updated.

input outputcompute()

NodeThe output of

other node

The input of

other node


Hypergraph

A window that allows you to see the nodes in their DAG hierarchical

form or as the DG nodes

It doesn‟t allow you to see them both at the same time.

Default existing nodes in Maya through Hypergraph


Hypergraph

The connection lines are color-coded to indicate the type of attribute

that is connecting the nodes.

You can change these default colors in the Colors window (Window >

Settings/Preferences > Colors).

A dotted line in the scene hierarchy indicates a connection to an

underworld node or an instanced object.

blue

cyan

green

magenta

Color

single

double

triple

data

Type

transform.translateX

makeNurbsSphere.radius

file.repeatUV

cameraShape.cameraAperature

transform.translate

lambert.color

nurbsSurface.create

makeNurbsSphere.outputSurface

Examples

red arrayparticleShape.position

particleShape.velocity


“time1” node

It is the instance of “time” node.

It is globally exists from when Maya started.

It is a trigger node for animation & simulation.


Introduction

to

MEL script


How to execute MEL scripts

Command Shell

Window > General Editors > Command Shell …

Script Editor

Window > General Editors > Script Editor …

Command Line


Variable Naming Convention

All variables in MEL begin with „$‟.

int $a = 1;

double $b = 1.1;

string $c = “1.1”;

Variables can‟t contain whitespace (spaces, tabs, …)

Variables can‟t have names that start with a number.

Variable names are also case sensitive.

Reserved words

break, case, continue, default, do, else, false, float, for, global, if, in, int,

matrix, no, off, on, proc, return, string, switch, true, vector, while, yes, global,

source, catch, alias, proc, …etc.

MEL commands


Variable Types

int int $i = 1;

float float $f = 1.1;

string string $s = “myName”;

vector vector $v = << 1.0, 2.0, 3.0 >>;

matrix matrix $m[3][3] = << 11, 12, 13; 21, 22, 23; 31, 32, 33 >>;

※ There are not “bool” & “double” type in MEL.


Cautions

Integer division truncation

float $a = 3 / 2; // result : 1

float $a = 3.0 / 2; // result : 1.5

float $a = (float)3 / 2; // result : 1.5

float $a = 3 / (float)2; // result : 1.5

Precision range

int $a = 2147483647 + 1; // result : -2147483648

int $a = -2147483648 – 1; // result : 2147483647

int $a = 2147483648; // result : -2147483648

int $a = 2147483647 + 2; // result : -2147483647

※ It depends on machine.


Array

int $intArray[2] = { 1, 2 };

intArray[0] = 3;

intArray[1] = 4;

float $floatArray[3] = { 1.1, 2.1, 3.1 };

floatArray[2] = 0.1;

string $stringArray[3] = { “abc”, “def”, “ghi” };

print $stringArray[0]; print “\n”



vector $vectorArray[2] = { <<1,2,3>>, <<4,5,6>> };

matrix $m[3][3] = << 11, 12, 13; 21, 22, 23; 31, 32, 33 >>;


Procedure

It is same as function of C / C++.

Procedure = function = command

global proc [return value] aaa( [parameters] )

{

…

}

Example

global proc string helloValue( int $number, string $name )

{

string $result;

$result = “Your name : ” + $name + “, your number : ” + $number;

return $result;

}


Others are similar to C / C++

Data-type conversions float $f = 4.0 / 3.0;

Comparison operators <, >, >=, <=, ==, !=

Logical operators &&, ||, !

Conditional statement if( 1 > 2 ) { … } else { … } switch( … ) { case 1: … }

Loop statement int $i=0; for( ; $i<100; i++ ) { … } while( … ) { … }

Comment // /* … */


Global vs Local

Local variables

They are accessible only within their block.

Global variables

Once a variable is defined as global,

it is accessible anytime and anywhere throughout Maya.

// Block 1{

int $a = 1;

// Inner Block 2{

int $b = 2;print $a;

}

print $b; // error!}


MEL script

Examples


MEL Command Mode

Creation mode

with no flag

A command generates a new object.

Query mode

with -query flag

A command retrieves the value of the parameter specified.

Edit mode

with –edit flag

A Command changes a given property of an object.


MEL Command Mode (Examples)

Create mode

sphere –name Sphere01;

Query mode

sphere –query –radius Sphere01;

Edit mode

sphere –edit -radius 2 Sphere01;


help


print / tokenizeList

$i=10;

print $i;

$f=3.1415926535;

print $f;

$s = “Hello Everyone”;

print $s;

vector $v = << 1.1, 2.2, 3.3 >>;

print $v;

matrix $m[2][3] = << 1, 2, 3; 4, 5, 6; 7, 8, 9 >>;

print $m;

string $a = “1 , 3 4, 67”;

string $b[];

tokenizeList( $a, $b );

print $b;


ls / Back Quote(`) / eval

$objs = `ls -selection`;

for( $obj in $objs )

{

print($obj + " ");

};

ls;

ls –type surfaceShape;

ls –showType;

ls -sl;

string $s[] = `sphere`;

print $s[0];

print $s[1];

string $cmdName = “sphere”;

eval( $cmdName + “ –r 5” );

eval( $cmdName + “ –r 10” );

ls -selection;


pickWalk / listRelatives

string $Shape = `createNode nurbsSurface`;

string $Transform[] = `listRelatives -p $Shape`;


string $Transform[] = `listRelatives -p $Shape`;


select $Shape;

string $Transform[] = `pickWalk -d up`;

string $again[] = `listRelatives –c $Transform[0]`;

print $again[0];

print “\n”;


select $Shape;

string $Transform[] = `pickWalk -d up`;


More on “ls” command

global proc testMEL() {

string $selected[] = `ls -sl -type transform`;for( $obj in $selected ) { print $obj; }

}


string $selected[] = `ls -sl -type transform`;for( $obj in $selected ) {

string $meshShape[];$meshShape = `listRelatives -c $obj`;print $meshShape;

}}


string $selected[] = `ls -sl -type transform`;for( $obj in $selected ) {

string $meshShape[];$meshShape = `listRelatives -c $obj`;string $type = `nodeType $meshShape[0]`;if( $type == "mesh" )

print $meshShape;}

}


listAttr / getAttr / setAttr

polySphere;

listAttr pSphere1;

getAttr pSphere1.tx;

setAttr pSphere1.tx 10;

string $inSurfaceTransform[] = `sphere`;

string $inSurfaceShape[] = `listRelatives -c $inSurfaceTransform`;

eval( "setAttr " + $inSurfaceTransform[0] + ".tx -5" );

eval( "setAttr " + $inSurfaceTransform[0] + ".ty 0" );

eval( "setAttr " + $inSurfaceTransform[0] + ".tz -3" );


pluginInfo

int $isLoaded = `pluginInfo -q -l “testNode.mll"`;

if( !$isLoaded )

{

loadPlugin “testNode.mll";

}


playbackOptions

This command sets/queries certain values associated with playback.

playbackOptions -q -ast;

0

playbackOptions -q -min;

10

playbackOptions -q -max;

90

playbackOptions -q -aet;

100

playbackOptions -e -ast 1;

playbackOptions -e -min 1;

playbackOptions -e -max 1000;

playbackOptions -e -aet 1000;


createNode / connectAttr

global proc testMEL()

{

int $isLoaded = `pluginInfo -q -l “testNode.mll"`;

if (!$isLoaded)

{

loadPlugin "testNode.mll";

}

string $selected[] = `ls -sl -type transform`;

for( $obj in $selected )

{

string $inMesh[] = `listRelatives -c $obj`;

string $outMesh[] = `polySphere`;

string $testNode = `createNode testNode`;

connectAttr ($inMesh[0] + ".worldMesh") ($testNode + ".inputMesh");

connectAttr ($testNode + ".output") ($outMesh[0] + ".tx" );

}

}


createNode / connectAttr (polygon)

global proc test()

{

// input

string $inMeshTransform[] = `polySphere`;

string $inMeshShape[] = `listRelatives -c $inMeshTransform[0]`;

// output

string $outMeshTransform = `createNode transform`;

string $outMeshShape = `createNode mesh –p $outMeshTransform`;

sets -add initialShadingGroup $outMeshShape;

// intermediate


connectAttr ( $inMeshShape[0] + “.worldMesh”) ( $testNode + “.inputMesh” );

connectAttr ( $testNode + “.outputMesh” ) ( $outMeshShape + “.inMesh” );

};


createNode / connectAttr (NURBS Surface)

global proc test()

{

// input

string $inSurfaceTransform[] = `sphere`;

string $inSurfaceShape[] = `listRelatives -c $inSurfaceTransform[0]`;

// output

string $outSurfaceShape = `createNode nurbsSurface`;

string $outSurfaceTransform[] = `listRelatives -p $outSurfaceShape`;

sets -add initialShadingGroup $outSurfaceShape;

// intermediate


connectAttr ( $inSurfaceShape[0] + “.worldSpace” ) ( $testNode + “.inSurface” );

connectAttr ( $testNode + “.outSurface” ) ( $outSurfaceShape + “.create” );

};


Expression


Expression

Expressions can be used to create complex animations with little or no

manual intervention.

Generally, any attribute can be controlled by an expression.

Ex.) nurbsSphere1.translateX = frame;


GUI

using

MEL


ELF

ELF (Extended Layer Framework)


Maya

Environment

Variables


Two Environment Variables

MAYA_PLUG_IN_PATH

MAYA_SCRIPT_PATH


Two Environment Variables

MAYA_PLUG_IN_PATH

Its order is the order of plug-ins in Maya “Plug-in Manager”.

MAYA_SCRIPT_PATH

The .mel files in the folder of this path can be executed in the Maya.


Visual C++

Development

Environment

Settings


Maya Plug-in Wizard

Maya 6.0

Wizard will be installed automatically.

Maya 6.5 & 7.0

At this time the Maya install process will not copy the wizard files into the

appropriate .NET directories. This process should be done manually.

Alternative way

After installing Maya 6.0 & 6.5, create VC 6.0 project using

MayaPluginWizard for Maya 6.0.

And then, change the path of libraries to be linked into ones of Maya 6.5 or

7.0.


How to install Wizard (MS VS.NET)

Please, go to following folder.“C:\Program Files\Alias\Maya7.0\devkit\pluginwizard”

MayaPluginWizard2.0.zip One folder

Maya PlugIn Wizard Three files

MayaPlugInWizard.ico MayaPlugInWizard.vsdir MayaPlugInWizard.vsz

Copy the three files to Visual Studio.NET 2003

“C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\vcprojects” Visual Studio.NET 2005

“C:\Program Files\Microsoft Visual Studio 8\VC\vcprojects”

Copy the folder to Visual Studio.NET 2003

“C:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\VCWizards” Visual Studio.NET 2005

“C:\Program Files\Microsoft Visual Studio 8\VC\VCWizards”


How to create a project

File > New > Project

VS.NET 2003

VS.NET 2005


Directories Setting (VS.NET 2003)

Tools > Options



Or set in “project properties”.



Tools > Options



Or set in “project properties”.


Libraries to be linked

OpenGL32.lib

- Classes for using OpenGL

Foundation.lib

- Fundamental classes for MAYA

OpenMaya.lib

- Classes for defining nodes and commands

OpenMayaUI.lib

- Classes for creating new user interface elements

OpenMayaAnim.lib

- Classes for deformers and inverse kinematics

OpenMayaRender.lib

- Classes for rendering

OpenMayaFX.lib

- Classes for dynamics


Link Libraries (VS.NET 2003)

Set in “project properties”.

Or set in source code.

#pragma comment( lib, "Foundation.lib" )

#pragma comment( lib, "OpenMaya.lib" )


My FirstMaya

plug-in


Common Code of Maya plug-in

Create “empty” project & type following code.



#include <maya/MFnPlugin.h>

MStatus initializePlugin( MObject obj )

{

MStatus stat;

MFnPlugin plugin( obj, “My Company”, “1.0”, “Any” );

return stat;

}

MStatus uninitializePlugin( MObject obj )

{

MStatus stat;

MFnPlugin plugin( obj );

return stat;

}


initializePlugin(), uninitializePlugin()

initializePlugin()

It is called immediately after the plug-in is loaded.

It registers command, node, and so on.

uninitializePlugin()

It is called before the plug-in is unloaded.

It deregisters what were registered in initializePlugin().


Load plug-in

Window > Settings/Preferences > Plug-in Manager

Browse & select “testPlugIn.mll” file in “Debug” or “Release” folder.

“testPlugIn” is loaded, but it doesn‟t do anything because it is empty.

※ You must ensure that your plugin is unloaded before linking.


Command

plug-in


Minimal Code for Command Plug-in

#include <maya/MPxCommand.h>

class testCmd : public MPxCommand

{

public:

MStatus doIt( const MArgList& args );

static void* creator() { return new testCmd; };

};

#include "testCmd.h"

MStatus testCmd::doIt( const MArgList& args )

{

MStatus stat;

return MS::kSuccess;

}

testCmd.h

testCmd.cpp


Minimal Code for Command Plug-in

#include <maya/MFnPlugin.h>#include "testCmd.h"

MStatus initializePlugin( MObject obj ){

MStatus stat;MFnPlugin plugin( obj, “My Company”, “1.0”, “Any” );

stat = plugin.registerCommand( “testCmd”, testCmd::creator );if( !stat ) {

stat.perror( “Register Command Failure!” );return stat;

}return stat;

}

MStatus uninitializePlugin( MObject obj ){

MStatus stat;MFnPlugin plugin( obj );

stat = plugin.deregisterCommand( “testCmd” );if( !stat ) {

stat.perror( “Deregister Command Failure!” );return stat;

}return stat;

}

pluginMain.cpp


Load plug-in & execute it.

Load through “Plug-in Manager”.

Execute it.

Nothing happened, but it is successively executed.


MPxCommand

It provides all the functionalities necessary for maya to use the

command as if it were built in.


doIt()

It does the real work of the command.

It is called when the command is executed


Print out

& String

in Maya


MGlobal::displayInfo()

#include "testCmd.h"#include <maya/MGlobal.h>#include <maya/MString.h>

MStatus testCmd::doIt( const MArgList& args ){

MStatus stat;

char buffer[256];sprintf( buffer, "%s", "Hi~" );MGlobal::displayInfo( buffer );MGlobal::displayInfo( "friends.\n" );MGlobal::displayInfo( MString("Goodbye") + "\n" );MGlobal::displayInfo( "..." );

return MS::kSuccess;}


Methods for Printing Out

printf( “…”);

#include <stdio.h>

Print out in “Output Window”

Caution : It will not be printed immediately.

MGlobal::displayInfo( MString( “…” ) );

#include <maya/MGlobal.h>

Print out in “Script Editor” & “Command Feedback Line”


Printing Out for Error Messages

displayError


MGlobal::displayError( “Error!” );

Print out in “Command Feedback” & “Script Editor”

perror

#include <maya/MStatus.h> or none

MStatus stat = MS::kFailure;

stat.perror( “Error!” );

Print out in “Output Window”


MString

#include <maya/MString.h>

String class to be used in Maya

Examples

MString txt( “Position : ” );

float pos = 10.f;

MGlobal::displayInfo( txt + pos );

unsigned int num = 10;

MGlobal::displayInfo( Mstring(“num:”) + num );

MString str( “3.14159” );

float pi = str.asFloat();


MObject & Function Sets

MObject

Maya owns the actual data and never gives you direct access to it.

It is the generic class for accessing all Maya internal objects.

curve, surface, mesh, node, plug, light, shader, texture, etc.

It is just a handle to an object inside the core.

It can be thought of as a pointer to some internal data.

Function set

It is C++ classes which operate on objects.

MFn prefix indicates this.


Dependency

Node

plug-in


DG Node Plug-in

You can define your own type of node in Maya.

User-defined nodes are derived from the MPxNode class.

It is the base class for user defined DG node.

When an input changes, the compute() method is called.

User-defined nodes must have both input & output attributes.

If there are neither input or output connection to other nodes,

this node will do nothing.

All input & output attributes must be the type of MObject.

All variables for input & output attributes must be type of static.

They must be initialized at the outside of the class.


An Example of Simple DG Node (1/6)

testNode.h#ifndef _TESTNODE_H_#define _TESTNODE_H_

#include <maya/MPxNode.h>

class testNode : public MPxNode{

public: // member variablesstatic MTypeId typeID; // node IDstatic MString typeName; // node namestatic MObject input; // input attributestatic MObject output; // output attribute

public: // member functionsstatic void* creator() { return new testNode(); };virtual MStatus compute( const MPlug& plug, MDataBlock& data );static MStatus initialize();

};

#endif



testNode.cpp#include "testNode.h"#include <maya/MFnNumericAttribute.h>

// unique dependency node ID & NameMTypeId testNode::typeID( 0x00001 );MString testNode::typeName( "testNode" );

// initialization for 'static' member variables as NULLMObject testNode::input;MObject testNode::output;

MStatus testNode::initialize(){

…}

MStatus testNode::compute( const MPlug& plug, MDataBlock& data ){

…}

Don’t use the existing ID & name in Maya.




MStatus stat;

MFnNumericAttribute nAttr;

// 1/3) create & set attributesinput = nAttr.create( "input", "in", MFnNumericData::kDouble, 1.0, &stat );nAttr.setConnectable( true );output = nAttr.create( "output", "out", MFnNumericData::kDouble, 1.0, &stat );nAttr.setConnectable( true );

// 2/3) add attributesaddAttribute( input );addAttribute( output );

// 3/3) set causalityattributeAffects( input, output );

return stat;}

Don’t use the existing long name or short name in Maya.




MStatus stat;

if( plug == output ) { // which output attribute is requested to be recomputed

MDataHandle inputHnd = data.inputValue( input, &stat );double inputValue = inputHnd.asDouble();

MDataHandle outputHnd = data.outputValue( output );outputHnd.set( 2*inputValue );

data.setClean( plug ); // inform the DG that the given plug has been updated} else {

return MS::kUnknownParameter; // other attributes to be treated in parent node}

return stat;}



#include "testNode.h"



{

MStatus stat;

MFnPlugin plugin( obj, “My Company", "1.0", "Any" );

// Register testNode

stat = plugin.registerNode( testNode::typeName, testNode::typeID,

testNode::creator, testNode::initialize );

if( !stat ) { stat.perror( "registerNode" ); return stat; }

return stat;

}

MStatus uninitializePlugin( MObject obj)

{

MStatus stat;


// Deregister testNode

stat = plugin.deregisterNode( testNode::typeID );

if( !stat ) { stat.perror( "deregisterNode" ); return stat; }

return stat;

}

pluginMain.cpp


DG Node ID

Identifier in the binary file format

32bit value (0x00000000 ~ 0x0007ffff)

It must be unique in your work of Maya.

For any node for permanent purposes, you should get a universally unique ID from Alias|Wavefront Assist.


Member Functions

creator()

It is called every time a new instance of the node is requested by either the

createNode MEL command or MFnDependencyNode::create() method.

It allows Maya to instantiate instances of this node.

initialize()

It is called by the registration mechanism for DG nodes.

It is used to define the inputs and ouputs of the node.

compute(…)

It is called whenever outputs should be newly calculated.

It does the actual work of the node.

It uses the inputs in the node to generate its outputs.


Plugs

Which output attribute the recompute is being requested for?

if( plug == output1 ) {…}

else if( plug == output2 ) {…}

else if( plug == output3 ) {…}

else return MS::kUnknownParameter;

It lets Maya know that the recomputing is done and it holds the now

correct value.

data.setClean( plug );


Data Blocks

It contains all the data for this instance of the node.

For efficiency this data is kept as a single block.

You need to specify which of the attributes you want to retrieve.

The data is retrieved from the data handle thru. as*().

It must matches the declared type of the attribute.


Attribute Properties

Readable

PropertyCan be the source of connections

Descriptiontrue

Default

Writable Can be the destination of connections true

Connectable Can be connected (superior to ‘readable’ & ‘writable’) true

Storable Is stored to scene files true

Keyable Can be animated false

Hidden Is hidden false

UsedAsColor Treat values as colors false

Cached Value is cached true

Array Is an array false

IndexMatter Index shouldn’t change true

ArrayDataBuilder Uses array data builder to set value false

Indeterminant Determines if it can be used in an evaluation false

DisconnectBehavior Behavior after disconnection kNothing

Internal Is internal to the node false

RenderSource Overrides rendering sampling information false


Compound Attribute

A compound attribute is used to group other attributes.

Children : the grouped attributes

Parent : itself

Representative of compound attribute : boundingBox


Deformer

Node

plug-in


Deformer

It takes a series of points and moves them to new location.

It cannot create or remove points.

It can modify the location of

Lattice points

Control vertices

Polygonal vertices

It is created by deriving from the MPxDeformerNode class.

The major difference from other node

deform() instead of compute()


Deformer Node Example (1/3)

#include <maya/MPxDeformerNode.h>

#ifndef __TESTDEFORMER_H_

#define __TESTDEFORMER_H_

class testDeformer : public MPxDeformerNode

{

public:

static void *creator() {return new testDeformer(); };

static MStatus initialize() { return MS::kSuccess; };

virtual MStatus deform( MDataBlock &block,

MItGeometry &iter,

const MMatrix &mat,

unsigned int multiIndex );

};

#endif

testDeformer.h



#include <maya/MFnMatrixAttribute.h>#include <maya/MMatrix.h>#include <maya/MItGeometry.h>#include <maya/MDagModifier.h>#include <maya/MPoint.h>#include "testDeformer.h"

MTypeId testDeformer::typeId( 0x00111 );MString testDeformer::typeName( "testDeformer" );

MStatus testDeformer::deform( MDataBlock& block, MItGeometry &iter,const MMatrix &localToWorld, unsigned int geomIndex )

{MStatus stat;MDataHandle envData = block.inputValue( envelope );float env = envData.asFloat();if( env == 0.0 ) // Deformer has no effect

return MS::kSuccess;MPoint pt;for( iter.reset(); !iter.isDone(); iter.next() ) { // per each point to be deformed

pt = iter.position(); pt = pt * 1.5;iter.setPosition( pt );

}return stat;

}

testDeformer.cpp




#include "testDeformer.h"



#pragma comment( lib, "OpenMayaAnim.lib" )


{

MStatus status;

MFnPlugin plugin( obj, “My Company", “1.0", "Any");

plugin.registerNode( testDeformer::typeName,

testDeformer::typeId,

testDeformer::creator,

testDeformer::initialize,

MPxNode::kDeformerNode );

return status;

}

MStatus uninitializePlugin( MObject obj )

{

MStatus status;


stat = plugin.deregisterNode( testDeformer::typeId );

return status;

}

pluginMain.cpp


deform()

The major function to implement in a deformer node

1) MDataBlock &block

It holds the datablock for the deformer node.

It is the same datablock as one passed into compute().

2) MItGeometry &iter

An iterator for traversing all the points int the geometric object.

Control vertices, lattice points, mesh vertices, etc.

3) MMatrix &mat

Local to world transformation

When points are given to the deformer, their positions are in the local space.

If you want to deform in world space, transform the points using this matrix.

However, return them to local space by using the inverse of this matrix.

4) unsigned int geomIndex

It is possible for a deformer to deform

multiple geometry nodes

multiple components of a single geometry node.


Changes in Hypergraph

polySphere;



deformer -type testDeformer



“pSphereShape1Org” node

Exact duplication of the input mesh shape

( “pSphereShape1” before the deformer was applied )

“testDeformer1” node

An instance of the “testDeformer” deformer node

“pSphereSpahe1” node

The final geometry shape node


Locator

Node

plug-in


Locator

It provides users with a 3D visual handle.

Manipulation

Control

It won‟t appear in the final rendered image.

It is similar to general DG node. (OpenGL drawable DG node.)

It is derived from “MPxNode” class.

Main difference : draw()

compute() is also available

Other additional member functions

raw(), isBounded(), boundingBox(), color(), colorRGB()


draw()

You are free to draw the locator in any way you like.

Almost all OpenGL functions are available for drawing.

1) M3dView &view

Current Maya viewport in which the locator will be drawn.

2) const MDagPath &path

Complete DAG path to this locator node

3) M3dView::DisplayStyle style

Drawing mode definitions

4) M3dView::DisplayStatus status

The current state of the node in the viewport


isBounded(), boundingBox()

isBounded()

It is called when Maya needs to determine if the node knows its own

bounding extents.

If it returns „false‟, you don‟t need to implement boundingBox().

boundingBox()

It is called to retrieve the actual extents of the locator shape.

It is highly recommended to implement these function.

Without them, Maya has difficulty determining the exact size of the locator,

so the Frame All and Frame Selection operations will result in incorrect

zooming.


Locator Node Example (1/3)

#include <maya/MPxLocatorNode.h>#include <maya/M3dView.h>#include <maya/MString.h>#include <maya/MTypeId.h>

#ifndef __TESTLOCATOR_H_#define __TESTLOCATOR_H_

class testLocator : public MPxLocatorNode{

public:virtual void draw( M3dView &view, const MDagPath &path,

M3dView::DisplayStyle style,M3dView::DisplayStatus status );

virtual bool isBounded() const { return false; };virtual MBoundingBox boundingBox() const;static void *creator() {return new testDeformer(); };static MStatus initialize() { return MS::kSuccess; };

public:static MTypeId typeId;static MString typeName;

};#endif

testLocator.h



#include "testLocator.h"

MTypeId testLocator::typeId( 0x00111 );MString testLocator::typeName( "testLocator" );

void BasicLocator::draw( M3dView & view, const MDagPath & path,

M3dView::DisplayStyle style, M3dView::DisplayStatus status )

{

view.beginGL();

glPushAttrib( GL_CURRENT_BIT );

glBegin(GL_LINES);

glVertex3f( -0.5f, 0.0f, 0.0f );

glVertex3f( 0.5f, 0.0f, 0.0f );

glVertex3f( 0.0f, 0.0f, -0.5f );

glVertex3f( 0.0f, 0.0f, 0.5f );

glEnd();

glPopAttrib();

view.endGL();

}

testLocator.cpp



#include <maya/MFnPlugin.h>#include "testLocator.h"

#pragma comment( lib, "Foundation.lib" )#pragma comment( lib, "OpenMaya.lib" )#pragma comment( lib, “OpenMayaUI.lib” ) #pragma comment( lib, “opengl32.lib” )

MStatus initializePlugin( MObject obj ){

MStatus status;MFnPlugin plugin( obj, “My Company", “1.0", "Any");

plugin.registerNode( testLocator::typeName, testLocator::typeId, testLocator::creator, testLocator::initialize, MPxNode::kLocatorNode );

return status;}

MStatus uninitializePlugin( MObject obj ){

MStatus status;MFnPlugin plugin( obj );plugin.deregisterNode( testDeformer::typeId );return status;

}

pluginMain.cpp


Maya

Stand-alone

Application


Stand-alone Application

It contains the main routine for the application and makes API calls to

access Maya in batch mode.


An Example

#include <maya/MLibrary.h>

#include <maya/MIOStream.h>


int main(int argc, char **argv)

{

MStatus status;

status = MLibrary::initialize (true, argv[0], true);

if ( !status ) {

status.perror("MLibrary::initialize");

return (1);

}

// Write the text out in 3 different ways.

cout << "Hello World! (cout)\n";

MGlobal::displayInfo("Hello world! (script output)" );

MGlobal::executeCommand( "print \"Hello world! (command script output)\\n\"", true );

MLibrary::cleanup();

return (0);

}


User

Defined

Attributes


User Defined Attribute (1/4)

#include <maya/MPxData.h>

class definedType : public MPxData{

public:static const MString typeName;static const MTypeId id;…

public:static void *creator() {return new definedType; };…

};

definedType.h

All user defined connectable attribute of node

that is to be passed between nodes in the dependency graph

must be derived from MPxData.

#include “definedType.h”

const MTypeId definedType::id( 0xF1000 );

const MString definedType::typeName( “definedType” );

…

definedType.cpp



#include <maya/MPxNode.h>

#include <maya/MTypeId.h>

#include <maya/MString.h>

class testNode : public MPxNode

{

public:

static MTypeId id;

static MString typeName;

MObject input;

MObject output;

public:

virtual MStatus compute( const MPlug& plug, MDataBlock& data );

static void* creator() { return new testNode; };

static MStatus initialize();

void Modifier( definedType *in, definedType *out );

};

testNode.h



#include “testNode.h”#include <maya/MFnTypedAttribute.h>#include <maya/MFnPluginData.h>

const MTypeId testNode::id( 0xF1100 );const MString testNode::typeName( “testNode” );

MObject testNode::input;MObject testNode::output;


MFnTypedAttribute tAttr;

input = tAttr.create( "input", "in", definedType::id, MObject::kNullObj );output = tAttr.create( "output", "out", definedType::id, MObject::kNullObj );

addAttribute( input );addAttribute( output );

attributeAffects( input, output );}

testNode.cpp




if( plug == output ) {MDataHandle inputDataHnd = data.inputValue( input );definedType *dType = (defineType*)inputDataHnd.asPluginData();

MDataHandle outputDataHnd = data.outputValue( output );MFnPluginData dataCreator;MObject newDataObject = dataCreator.create( definedType::id );definedType *newData = (definedType*)dataCreator.data();Modifier( dType, newData );outputDataHnd.set( newData );

}}

void testNode::Modifier( definedType *in, definedType *out ){

…}

testNode.cpp


Maya

plug-in

Tips


How to execute MEL command

MGlobal::executeCommand( “sphere –p 0 0 0 –r 1” );

MStringArray Locator;

MGlobal::executeCommand( MString( "spaceLocator -p " ) + p0.x + " " + p0.y + " " + p0.z, Locator );

MGlobal::displayInfo( MString( “Locator Name : ” + Locator[0] );


How to get selected meshes

#include <maya/MSelectinList.h>

#include <maya/MItSelectinList.h>

#include <maya/MDagPath.h>

#include <maya/MFnMesh.h>

MSelectionList selection;

MGlobal::getActiveSelectionList( selection );

MDagPath dagPath;

MFnMesh meshFn;

MItSelectionList iter( selection, MFn::kMesh );

for( ; !iter.isDone(); iter.next() )

{

iter.getDagPath( dagPath );

meshFn.setObject( dagPath );

…

}


How to get time attribute


{ …

static MObject inTime;

…

};

#include <maya/MTime.h>

#include <maya/MFnUnitAttribute.h>

MObject testNode::inTime;

MStatus testNode::initialize()

{

MFnUnitAttribute uAttr;

inTime = uAttr.create( "inTime", "it", MFnUnitAttribute::kTime );

…

}

MStatus testNode::compute( const MPlug& plug, MDataBlock& data )

{

MDataHandle inTimeHnd = data.inputValue( inTime );

MTime time = inTimeHnd.asTime();

…

}


How to get bool attribute


{ …

static MObject inValue;

…

};

#include <maya/MFnNumericAttribute.h>

MObject testNode::inValue;


{


inValue = nAttr.create( "inVal", "iv", MFnNumericData::kBoolean, true );

…

}


{

MDataHandle inValueHnd = data.inputValue( inValue );

bool inVal = inValueHnd.asBool();

…

}


How to get int attribute


{ …


…

};




{


inValue = nAttr.create( "inVal", "iv", MFnNumericData::kInt, 1 );

…

}


{


int inVal = inValueHnd.asInt();

…

}


How to get double attribute


{ …


…

};




{


inValue = nAttr.create( "inVal", "iv", MFnNumericData::kDouble, 1.0 );

…

}


{


double inVal = inValueHnd.asDouble();

…

}


How to get NURBS curve


{ …

static MObject inCurve;

…

};

#include <maya/MFnNurbsCurve.h>

#include <maya/MFnTypedAttribute.h>

MObject testNode::inCurve;


{

MFnTypedAttribut tAttr;

inCurve = tAttr.create( "inCurve", "ic", MFnData::kNurbsCurve );

…

}


{

MDataHandle inCurveHnd = data.inputValue( inCurve );

MObject inCurveObj = inCurveHnd.asNurbsCurve();

MFnNurbsCurve inCurveFn( inCurveObj );

…

}


How to get NURBS surface


{ …

static MObject inSurface;

…

};

#include <maya/MFnNurbsSurface.h>


MObject testNode::inSurface;


{


inSurface = tAttr.create( "inSurface", "ic", MFnData::kNurbsSurface );

…

}


{

MDataHandle inSurfaceHnd = data.inputValue( inSurface );

MObject inSurfaceObj = inCurveHnd.asNurbsSurface();

MFnNurbsSurface inSurfaceFn( inSurfaceObj );

…

}


How to get Mesh


{ …

static MObject inMesh;

…

};

#include <maya/MFnMeshData.h>


MObject testNode::inMesh;


{


inMesh = tAttr.create( "inMesh", "im", MFnMeshData::kMesh );

…

}


{

MDataHandle inMeshHnd = data.inputValue( inMesh );

MObject inMeshObj = inMeshHnd.asMesh();

MFnMesh inMeshFn( inMeshObj );

…

}

“inMesh” & “im” is reserved keyword

tAttr.create( "inputMesh", "inM", MFnMeshData::kMesh );


How to output Mesh


{ …

static MObject outMesh;

…

};




MObject testNode::outMesh;


{ MFnTypedAttribut tAttr;

outMesh = tAttr.create( “outputMesh", “outM", MFnMeshData::kMesh );

…

}


{ …

MFnMeshData dataCreator;

MObject newData = dataCreator.create();

MFnMesh mesh;

mesh.create( nVerts, nPolys, vertsArray, … , newData );

MDataHandle outMeshHnd = data.outputValue( outMesh );

outMeshHnd.set( newData );


}


How to output NURBS surface


{ …

static MObject outSurface;

…

};

#include <maya/MFnNurbsSurface.h>

#include <maya/MFnNurbsSurfaceData.h>


MObject testNode::outSurface;

MStatus testNode::initialize() {


outSurface = tAttr.create( “outSurface", “os", MFnData::kNurbsSurface );

…

}


…

MFnNurbsSurfaceData dataCreator;

MObject newOutSurface = dataCreator.create();

MFnNurbsSurface nurbsFS;

MObject newNurbs = nurbsFS.create( ctrlVerts, …, newOutSurface );

MDataHandle outSurfaceHnd = data.outputValue( outSurface );

outMeshHnd.set( newOutSurface );


}


How to copy NURBS surface

class testNode : public MPxNode {

static MObject inSurface;

static MObject outSurface;

};

#include <maya/MFnNurbsSurfaceData.h>


MObject testNode::inSurface;

MObject testNode::outSurface


MFnTypedAttribute tAttr;

inSurface = tAttr.create( “inSurface", “is", MFnData::kNurbsSurface );

outSurface = tAttr.creat( “outSurface”, “os”, MFnData::kNurbsSurface );

addAttribute( inSurface);

addAttribute( outSurface );

attributeAffects( inSuface, outSurface );

}

MStatus testNode::compute( const MPlug& plug, MDataBlock& data ) {

if( plug == outSurface ) {

MDataHandle inSurfaceHnd = data.inValue( inSurface );

MObject inSurfaceObj = inSurfaceHnd.asNurbsSurface();

MFnNurbsSurfaceData surfaceData( inSurfaceObj );

MObject outSurfaceObj = surfaceData.object();

MDataHandle outSurfaceHnd = data.inValue( outSurface );

outSurfaceHnd.set( outSurfaceObj );


}

}


How to limit numeric attribute value


{


inValue1 = nAttr.create( "inVal1", "iv1", MFnNumericData::kDouble, 1.0 );


nAttr.setMin(0.0);

nAttr.setMax(10.0);


nAttr.setMin(0.0);

nAttr.setSoftMax(10.0);


nAttr.setSoftMin(0.0);

nAttr.setSoftMax(10.0);

…

}


How to limit numeric attribute value

createNode testNode;

Attribute Editor : testNode1


How to get compound attribute

class testNode : public MPxNode {…static MObject output;static MObject iboundingBox;static MObject iboundingBoxMin;static MObject iboundingBoxMax;static MObject iboundingBoxSize;…

};

#include <maya/MFnCompoundAttribute.h>#include <maya/MFnNumericAttribute.h>

MObject testNode::input;MObject testNode::iboundingBox;MObject testNode::iboundingBoxMin;MObject testNode::iboundingBoxMax;MObject testNode::iboundingBoxSize;


MFnCompoundAttribute cAttr;MFnNumericAttribute nAttr;

output = nAttr.create( “output”, “out” );

iboundingBox = cAttr.create( “iboundingBox", “ibbox" );iboundingBoxMin = nAttr.create( “iboundingBoxMin”, “ibbmin”, MFnNumericData::k3Double );iboundingBoxMax = nAttr.create( “iboundingBoxMax”, “ibbmax”, MFnNumericData::k3Double );iboundingBoxSize = nAttr.create( “iboundingBoxSize”, “ibbsize”, MFnNumericData::k3Double );

testNode.h

testNode.cpp


How to get compound attribute

cAttr.addChild( iboundingBoxMin );

cAttr.addChild( iboundingBoxMax );

cAttr.addChild( iboundingBoxSize );

addAttribute( iboundingBox );

addAttribute( output );

attributeAffects( iboundingBoxMin, output );

attributeAffects( iboundingBoxMax, output );

attributeAffects( iboundingBoxSize, output );

…

}


…

MDataHandle iboundingBoxMinHnd = data.inputValue( iboundingBoxMin );

MVector minPosition = iboundingBoxMinHnd.asDouble3();

MDataHandle iboundingBoxMaxHnd = data.inputValue( iboundingBoxMax );

MVector maxPosition = iboundingBoxMaxHnd.asDouble3();

MDataHandle iboundingBoxSizeHnd = data.inputValue( iboundingBoxSize );

MVector bBoxSize = iboundingBoxSizeHnd.asDouble3();

…

}


How to get node itself

MPxNode::thisMObject()

It returns the MObject associated with this user defined node.

#include <maya/MFnDependencyNode.h>


…

if( plug == output ) {

…

MFnDependencyNode dependNodeFn( thisMObject() );

…

}

…

}


How to get MObject by node’s name


#include <maya/MDagPath.h>

#include <maya/MStringArray.h>

#include <maya/MSelectionList.h>

#include <maya/MFnDependencyNode.h>

MStringArray testNodes;

MGlobal::executeCommand( MString( "ls -type testNode" ), testNodes );

for( int i=0; i<testNodes.length(); i++ ) {

MSelectionList sel;

MGlobal::getSelectionListByName( testNodes[0], sel );

MObject testNodeObj;

sel.getDependNode( i, testNodeObj );

MFnDependencyNode depFn( testNodeObj );

MString nodeName = depFn.name();

MGlobal::displayInfo( nodeName );

}


How to get array attribute


static MObject inValues;

};

#include <maya/MPlug.h>

#include <maya/MIntArray.h>


MObject testNode::inValues;



inValues = nAttr.create( “inValues", "iv", MFnNumericData::kDouble );

nAttr.setArray( true );

}


MFnDependencyNode depFn( thisMObject() );

MPlug inValuesPlg = depFn.findPlug( inValues );

int nElems = inValuesPlg.numElements();

MIntArray logicalIndex;

inValuesPlg.getExistingArrayAttributeIndices( logicalIndex );

for( int i=0; i<logicalIndex.length(); i++) {

double temp;

MPlug inValue = inValuesPlg.elementByLogicalIndex( logicalIndex[i] );

inValue.getValue( temp );

}

}


How to output array attribute


static MObject outputs;

};


#include <maya/MIntArray.h>


MObject testNode::outputs;



outputs = nAttr.create( “outputs", “outs", MFnNumericData::kDouble );

nAttr.setArray( true );

}


MFnDependencyNode depFn( thisMObject() );

MPlug outputsPlg = depFn.findPlug( outputs );

int nElems = outputsPlg.numElements();

MIntArray logicalIndex;

outputsPlg.getExistingArrayAttributeIndices( logicalIndex );

for( int i=0; i<logicalIndex.length(); i++) {

MPlug output = outputsPlg.elementByLogicalIndex( logicalIndex[i] );

output.getValue( 10.0 );

}

}


How to input / output array attribute


MStatus stat;

if( plug == outSurfaces ) {

MArrayDataHandle inSurfacesHnd = data.inputArrayValue( inSurfaces );

inSurfacesHnd.jumpToElement( plug.logicalIndex() );

MDataHandle inSurfaceHnd = inSurfacesHnd.inputValue();

MObject inSurfaceObj = inSurfaceHnd.asNurbsSurface();


MObject outSurfaceObj;

GenerateSurface( inSurfaceObj, outSurfaceObj );

MArrayDataHandle outSurfacesHnd = data.outputArrayValue( outSurfaces );

outSurfacesHnd.jumpToElement( plug.logicalIndex() );

MDataHandle outSurfaceHnd = outSurfacesHnd.inputValue();



} else {

return MS::kUnknownParameter;

}

return stat;

}


How to input / output array attribute

MStatus tetsNode::compute( const MPlug& plug, MDataBlock& data ) { MStatus stat;

if( plug == outSurfaces ) {

MObject thisNodeObj = thisMObject();

MFnDependencyNode thisNodeFn( thisNodeObj );

MPlug inSurfacesPlug = thisNodeFn.findPlug( inSurfaces );

MIntArray inSurfacesIndex;

inSurfacesPlug.getExistingArrayAttributeIndices( inSurfacesIndex );

for( unsigned int i=0; i<inSurfacesPlug.numConnecteElements(); i++ ) {

MPlug inSurfacePlug = inSurfacesPlug.elementByLogicalIndex( inSurfacesIndex[i] );

MObject inSurfaceObj;

inSurfacePlug.getValue( inSurfaceObj );


MObject outSurfaceObj;

GenerateSurface( inSurfaceObj, outSurfaceObj );

MArrayDataHandle outSurfacesHnd = data.outputArrayValue( outSurfaces );

outSurfacesHnd.jumpToElement( plug.logicalIndex() );

MDataHandle outSurfaceHnd = outSurfacesHnd.inputValue();


}


} else { return MS::kUnknownParameter; }

return stat;

}


How to get matrix attribute


…

static MObject inMatrix;

…

};

#include <maya/MFnMatrixAttribute.h>



MFnMatrixAttribute mAttr;

inMatrix1 = mAttr.create( "inMatrix", "im", MFnMatrixAttribute::kDouble );

…

}


MDataHandle inMatrixHnd = data.inputValue( inMatrix );

MMatrix inMat = inMatrixHnd.asMatrix();

…

}


Plug Connection Test

MFnDependencyNode thisDGNode( MPxNode::thisMObject() );

MPlug inputType1 = thisDGNode.findPlug( inValue1 , &stat );

MPlug inputType2 = thisDGNode.findPlug( inValue2, &stat );

if( inputType1.isConnected( &stat ) ) {...}


Traveling Dependency Graph

MStatus testCmd::doIt( const MArgList& ) {

MStatus stat;

MSelectionList selectedList;

MGlobal::getActiveSelectionList( selectedList );

MItSelectionList iter( selectedList );

for(; !iter.isDone(); iter.next() ) {

MObject thisNodeObj; MFnDependencyNode thisNodeFn;

MObject prevNodeObj; MFnDependencyNode prevNodeFn;

MObject nextNodeObj; MFnDependencyNode nextNodeFn;

selectedList.getDepenNode( 0, thisNodeObj );

thisNodeFn.setObject( thisNodeObj );

MPlug inputPlug = thisNodeFn.findPlug( "input" );

MPlugArray plugs;

inputPlug.connectedTo( plugs, true, false );

prevNodeObj = plug[0].node();

prevNodeFn.setObject( prevNodeObj );

plugs.clear();

MPlug outputPlug = thisNodeFn.findPlug( "output" );

outputPlug.connectedTo( plugs, false, true );

nextNodeObj = plug[0].node();

nexeNodeFn.setObject( nextNodeObj );

}

MGlobal::executeCommand( MString( "select -cl" ) );

return MS::kSuccess;

}


How to get “dag path” by “node name”

MString nodeName( "aaa" );

MString nodeName( "bbb" );

MSelectionList sList;

sList.add( node1Name );

sList.add( node2Name );

MDagPath dagPath1, dagPath2;

sList.getDagPath( 0, dagPath1 );

sList.getDagPath( 1, dagPath2 );


How to get & set “MPlug“ for MDoubleArray

MString nodeName = …;

MObject nodeObj = …;

MFnDependencyNode nodeFn( nodeObj );

Mplug plg = nodeFn.findPlug( nodeName );

MObject daData;

plg.getValue( daData );

MFnDoubleArrayData daFn( daData );

MDoubleArray dArray = daFn.array();

MString nodeName = …;

MObject nodeObj = …;

MDoubleArray dArray = …;

MFnDependencyNode nodeFn( nodeObj );

Mplug plg = nodeFn.findPlug( nodeName );

MFnDoubleArrayData daFn;

plg.setMObject( daFn.create( dArray ) );


How to copy from input Mesh to output Mesh


#include <maya/MObject.h>


#include <maya/MDataBlock.h>


void copyMesh( const MPlug& plug, MDataBlock& data )

{

MFnMesh newMeshFn;


MObject newMeshData = dataCreator.create();

newMeshFn.copy( data.inputValue( inMeshObj ).asMeshTransformed(), newMeshData );

data.outputValue( outMeshObj ).set( newMeshData );

}


How to get the shape node of a mesh

MDagPath dagPath; // transform node name

dagPath.extendToShape();

MFnMesh meshFn( dagPath );


How to get the “worldMatrix” of a shape node

Mobject thisNodeObj = thisMObject();

MFnDependencyNode fnThisNode( thisNodeObj );

MObject worldMatrixObj = fnThisNode.attribute( "worldMatrix", &stat );

MPlug worldMatrixPlg( thisNodeObj, worldMatrixObj );

worldMatrixPlg = worldMatrixPlg.elementByLogicalIndex( 0 );

MObject matrixObject;

stat = worldMatrixPlg.getValue( matrixObject );

if( !stat ) { stat.perror( "Failed to get worldMatrix object." ); }

MFnMatrixData worldMatrixData( matrixObject, &stat );

if( !stat ) { stat.perror( "Failed to get worldMatrix data." ); }

worldMatrix = worldMatrixData.matrix( &stat );

if( !stat ) { stat.perror( "Failed to get worldMatrix." ); }


How to get Fields in the current scene

#include <maya/MItDag.h>

#include <maya/MFnField.h>

for( MItDag it(MItDag::kDepthFirst, MFn::kField); !it.isDone(); it.next() )

{

MFnField fieldFn( it.item() );

…

}


How to copy from input mesh to output mesh


#include <maya/MObject.h>


#include <maya/MDataBlock.h>


void copyMesh( const MPlug& plug, MDataBlock& data )

{

MFnMesh newMeshFn;


MObject newMeshData = dataCreator.create();

newMeshFn.copy( data.inputValue( inMeshObj ).asMeshTransformed(), newMeshData );

data.outputValue( outMeshObj ).set( newMeshData );

}


How to get current view & camera

#include <maya/M3dView.h>

#include <maya/MFnCamera.h>

M3dView view = M3dView::active3dView();

MDagPath camDagPath;

View.getCamera( camDagPath );

MFnCamera cam( camDagPath );


Referneces

David A. D. Gould. 2003. Complete Maya Programming I. Morgan Kaufmann

David A. D. Gould. 2005. Complete Maya Programming II. Morgan Kaufmann

Alias|Wavefront. 2001. Maya Developer’s Tool Kit. Version 4. Alias|Wavefront

Hiroyuki Haga. 2003. Maya API Quick Start. Alias Entertainment

Alias Systems Corp. 2005. Maya API White Paper. Alias|Wavefront

조상범. 2002. programming with MAYA MEL & Expression. @rtisan(www.3DArtisan.com)

Mark R. Wilkins & Chris Kazmier. MEL Scripting for Maya Animators. Morgan Kaufmann

Shuen-Huei Guan, 2003, Introduction to Maya Programming (ppt),

http://graphics.csie.ntu.edu.tw/~drake/data/articles/IntroductionToMayaProgramming.ppt

Min Gyu Choi, Playing with Maya thru MEL/API. KCGS 2005 Tutorial

Rafael Baptista. How to Write a Simple Maya Model Exporter. http://www.gamedev.net/

Bryan Ewert. Maya API How-to. http://www.ewertb.com/maya

http://www.robthebloke.org/

maya programming for 3d graphics

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