scripted/circleNode.py

#-
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#
# Autodesk Script File
# MODIFY THIS AT YOUR OWN RISK
#
# Creation Date:   27 September 2006
#
# Example Plugin: circleNode.py
#
# This plug-in is an example of a user-defined dependency graph node.
# It takes a number as input (such as time) and generates two output
# numbers one which describes a sine curve as the input varies and
# one that generates a cosine curve. If these two are hooked up to
# the x and z translation attributes of an object the object will describe
# move through a circle in the xz plane as time is changed.
#
# See circleNodeTest.py for an example of how to use the node. The script will
# create a new "Circle" menu with a single item. Selecting this will build
# a simple model (a sphere which follows a circular path) which can be played back,
# by clicking on the "play" icon on the time slider.  Note: the circleNode
# plugin needs to be loaded before the "Circle" menu item can be executed
# properly.
#
# The node has two additional attributes which can be changed to affect
# the animation, "scale" which defines the size of the circular path, and
# "frames" which defines the number of frames required for a complete circuit
# of the path. Either of these can be hooked up to other nodes, or can
# be simply set via the command "maya.cmds.setAttr" operating on the circle node
# "circleNode1" created by the Python script. For example:
#
#   import maya.cmds as cmds
#   cmds.setAttr("circleNode1.scale", #)
#
# will change the size of the circle and:
#
#   cmds.setAttr("circleNode1.frames", #)
#
# will cause objects to complete a circle in indicated number of frames.
#

import math, sys

import maya.OpenMaya as OpenMaya
import maya.OpenMayaMPx as OpenMayaMPx

kPluginNodeTypeName = "spCircle"
kPluginNodeId = OpenMaya.MTypeId(0x87005)


# Node definition
class circle(OpenMayaMPx.MPxNode):
    # class variables
    aInput = OpenMaya.MObject()
    aScale = OpenMaya.MObject()
    aFrames = OpenMaya.MObject()
    aSOutput = OpenMaya.MObject()
    aCOutput = OpenMaya.MObject()


    def __init__(self):
        OpenMayaMPx.MPxNode.__init__(self)


    def compute(self, plug, data):
        # Check that the requested recompute is one of the output values
        if (plug == circle.aSOutput or plug == circle.aCOutput):
            # Read the input values
            inputData = data.inputValue(circle.aInput)
            scaleData = data.inputValue(circle.aScale)
            framesData = data.inputValue(circle.aFrames)

            # Compute the output values
            currentFrame = inputData.asFloat()
            scaleFactor  = scaleData.asFloat()
            framesPerCircle = framesData.asFloat()
            angle = 6.2831853 * (currentFrame/framesPerCircle)
            sinResult = math.sin(angle) * scaleFactor
            cosResult = math.cos(angle) * scaleFactor

            # Store them on the output plugs
            sinHandle = data.outputValue(circle.aSOutput)
            cosHandle = data.outputValue(circle.aCOutput)
            sinHandle.setFloat(sinResult)
            cosHandle.setFloat(cosResult)
            data.setClean(plug)
        else:
            return OpenMaya.kUnknownParameter

        return None


# creator
def nodeCreator():
    return OpenMayaMPx.asMPxPtr( circle() )


# initializer
def nodeInitializer():
    nAttr = OpenMaya.MFnNumericAttribute()

    # Setup the input attributes
    circle.aInput = nAttr.create("input", "in", OpenMaya.MFnNumericData.kFloat, 0.0)
    nAttr.setStorable(True)

    circle.aScale = nAttr.create("scale", "sc", OpenMaya.MFnNumericData.kFloat, 10.0)
    nAttr.setStorable(True)

    circle.aFrames = nAttr.create("frames", "fr", OpenMaya.MFnNumericData.kFloat, 48.0)
    nAttr.setStorable(True)

    # Setup the output attributes
    circle.aSOutput = nAttr.create("sineOutput", "so", OpenMaya.MFnNumericData.kFloat, 0.0)
    nAttr.setWritable(False)
    nAttr.setStorable(False)

    circle.aCOutput = nAttr.create("cosineOutput", "co", OpenMaya.MFnNumericData.kFloat, 0.0,)
    nAttr.setWritable(False)
    nAttr.setStorable(False)

    # Add the attributes to the node
    circle.addAttribute(circle.aInput)
    circle.addAttribute(circle.aScale)
    circle.addAttribute(circle.aFrames)
    circle.addAttribute(circle.aSOutput)
    circle.addAttribute(circle.aCOutput)

    # Set the attribute dependencies
    circle.attributeAffects(circle.aInput, circle.aSOutput)
    circle.attributeAffects(circle.aInput, circle.aCOutput)
    circle.attributeAffects(circle.aScale, circle.aSOutput)
    circle.attributeAffects(circle.aScale, circle.aCOutput)
    circle.attributeAffects(circle.aFrames, circle.aSOutput)
    circle.attributeAffects(circle.aFrames, circle.aCOutput)


# initialize the script plug-in
def initializePlugin(mobject):
    mplugin = OpenMayaMPx.MFnPlugin(mobject, "Autodesk", "1.0", "Any")
    try:
        mplugin.registerNode( kPluginNodeTypeName, kPluginNodeId, nodeCreator, nodeInitializer )
    except:
        sys.stderr.write( "Failed to register node: %s" % kPluginNodeTypeName )
        raise


# uninitialize the script plug-in
def uninitializePlugin(mobject):
    mplugin = OpenMayaMPx.MFnPlugin(mobject)
    try:
        mplugin.deregisterNode( kPluginNodeId )
    except:
        sys.stderr.write( "Failed to deregister node: %s" % kPluginNodeTypeName )
        raise