Hello everyone, i'm a newbee to maya python API.
Recently, I'm struggle in the single ray tracer.
I build a custom MPxNode to compute the hitPoint when the ray hit the
sphere.
The ray is build by 2 locators in space.
If the sphere is at the origin point of the world space, everything seems
OK.
But here is the* problem*:
When I transform the sphere object, e.x translate a little distance. The
hitPoint should translate on the sphere but now it doesn't .
I know that when I transform the sphere, the input values of the custom
node have't change and compute function doesn't be called.
I have tried that to add a transform attribute to call the compute function
but it doesn't work. I think the hitPoint should be calculate by multiply a
matrix.
So how can I achieve that when I transform the sphere, the hit point on the
sphere also change by the direction of the ray.
Thank you very much.
Here is the *code*:
import maya.OpenMaya as om
import maya.OpenMayaMPx as ompx
nodeName = 'RayTracer'
nodeID = om.MTypeId(0X100fff)
class MeshIntersectionNode(ompx.MPxNode):
# Class Attrs
# INPUT
Loc_1_Pos = om.MObject()
Loc_2_Pos = om.MObject()
inMesh = om.MObject()
# OUTPUT
Loc_3_Pos = om.MObject()
def __init__(self):
ompx.MPxNode.__init__(self)
def compute(self, plug, dataBlock):
if plug != MeshIntersectionNode.Loc_3_Pos:
return om.kUnknownParameter
locator1Vector =
om.MVector(dataBlock.inputValue(MeshIntersectionNode.Loc_1_Pos).asFloatVector())
locator2Vector =
om.MVector(dataBlock.inputValue(MeshIntersectionNode.Loc_2_Pos).asFloatVector())
inputMeshObj =
dataBlock.inputValue(MeshIntersectionNode.inMesh).asMesh()
direction = om.MFloatVector(locator2Vector - locator1Vector)
sourcePoint =
om.MFloatPoint(dataBlock.inputValue(MeshIntersectionNode.Loc_1_Pos).asFloatVector())
inputMeshMFn = om.MFnMesh(inputMeshObj)
hitPoints = om.MFloatPoint()
tolerance = float(0.0)
inputMeshMFn.closestIntersection(sourcePoint, direction, None, None,
False, om.MSpace.kWorld,
10000.0, False, None, hitPoints,
None, None, None, None, None, tolerance)
outputPoint = dataBlock.outputValue(MeshIntersectionNode.Loc_3_Pos)
if hitPoints[0]:
outputVector = om.MFloatVector(hitPoints.x, hitPoints.y,
hitPoints.z)
else:
outputVector = om.MFloatVector(0.0, 0.0, 0.0)
outputPoint.setMFloatVector(outputVector)
dataBlock.setClean(plug)
def nodeCreator():
return ompx.asMPxPtr(MeshIntersectionNode())
def nodeInitializer():
MFnNumericAttr = om.MFnNumericAttribute()
MFnMeshAttribute = om.MFnTypedAttribute()
# create attribute
# input
MeshIntersectionNode.Loc_1_Pos =
MFnNumericAttr.createPoint('Locator1Position', 'Loc1Pos')
MFnNumericAttr.setWritable(1)
MFnNumericAttr.setKeyable(1)
MeshIntersectionNode.addAttribute(MeshIntersectionNode.Loc_1_Pos)
MeshIntersectionNode.Loc_2_Pos =
MFnNumericAttr.createPoint('Locator2Position', 'Loc2Pos')
MFnNumericAttr.setWritable(1)
MFnNumericAttr.setKeyable(1)
MeshIntersectionNode.addAttribute(MeshIntersectionNode.Loc_2_Pos)
MeshIntersectionNode.inMesh = MFnMeshAttribute.create('inMesh', 'im',
om.MFnData.kMesh)
MFnMeshAttribute.setWritable(1)
MFnMeshAttribute.setKeyable(1)
MeshIntersectionNode.addAttribute(MeshIntersectionNode.inMesh)
# output
MeshIntersectionNode.Loc_3_Pos =
MFnNumericAttr.createPoint('Locator3Position', 'Loc3Pos')
MFnNumericAttr.setWritable(0)
MFnNumericAttr.setReadable(1)
MeshIntersectionNode.addAttribute(MeshIntersectionNode.Loc_3_Pos)
# make influence
MeshIntersectionNode.attributeAffects(MeshIntersectionNode.Loc_1_Pos,
MeshIntersectionNode.Loc_3_Pos)
MeshIntersectionNode.attributeAffects(MeshIntersectionNode.Loc_2_Pos,
MeshIntersectionNode.Loc_3_Pos)
MeshIntersectionNode.attributeAffects(MeshIntersectionNode.inMesh,
MeshIntersectionNode.Loc_3_Pos)
def initializePlugin(mObj):
mPlugin = ompx.MFnPlugin(mObj, 'Yixiong Xu', '1.0')
try:
mPlugin.registerNode(nodeName, nodeID, nodeCreator, nodeInitializer)
except:
raise RuntimeError
print 'Failed to register node.'
def uninitializePlugin(mObj):
mPlugin = ompx.MFnPlugin(mObj)
try:
mPlugin.deregisterNode(nodeID)
except:
raise RuntimeError
print 'Failed to deregister node.'
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