Circle node

From DreamsteepWiki

# 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.

# 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.MStatus.kUnknownParameter



		return OpenMaya.MStatus.kSuccess





# 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