Vertex Position In World Space

[matthew-austin]

I am struggling to have Maya tell me where a vertex is in world space.

I've tried getAttr $object.vtx[$i].translateX;
getAttr $object.vrtx[$i]
getAttr $object.vtx[$i].x

sorry if the syntax is off...just giving you an idea of the commands. The 2nd command reads and it gives you values but they cannot be the world values as in my function I need it for I am using a distance arguement and getting division by zero. Further still I have rotated the object (thus theoretically moving the vertecies and their values from the 2nd command, yet the values stay the same.

Is there a simple command issue or does this problem have to be solved by hard coding? If so, has anyone got a script that does it?

Cheers.

[joojaa]

pointPosition -w ($object+".vtx["+$i+"]")

getattr works on stored data and ALL DATA is in local space at all times, thats kind of the point of local space. Theres no attribute named objectname.vtx[index] as that is a alias so if you WANT the attribute you must ask the shape.

[efecto]

hi joojaa, xform -q -w works too right?

[joojaa]

Yes but you should use PointPosition

[m-macklin]

Is there any way to query a vertex position (worldspace) at a different time?

pointPosition and xform don't have time flags, and getAttr returns localspace.

[dsehgal]

Hi m macklin, I guess for that you can call this command at different time frames (using loops) and store the values in an array... give it a try !

[joojaa]

Cache the value.

Seriously tough yes its technically possible to do youd have the calculate the matrix multiplicatuion your self. However let me be clear here, you really want to avoid needing to do this like a plague. Beacuse its solw, it defeats the entire purpose of mayas dg in one swift move. This your sidestepping the entire reason your using maya in the firstplace, especially since you ask for a shape.

And offcourse if you were to do this offline heres really no point you can just change time. So id say you really ought to skip over to maya api RIGHT NOW.

[highend3djojan-]

umm.. wat u r tellin is 2 get attr val @ a dffrnt time using API? hwz it possibl? can u just writ it dwn here (if code is simple)? or shall i post dis specific Qn in API forum? i'm a beginner in API.

[highend3djojan-]

ok, got it:

# tim = 10, attr = 'tx'

tim = om.MTime(tim)
ctx = om.MDGContext(tim)

fnThisNode = om.MFnDependencyNode ( thisNode )   # thisNode is MObject
plug = fnThisNode.findPlug( attr )
print plug.asFloat(ctx)

[joojaa]

see the point is by the time youve bothred to do this in the api and you notice its slow you get that thres NOTHING you can do to speed it up.

seriously its a bad idea. you are firing the dg 2 times eacg time you ask for something at different time. Worse yet since the shape has to compute all points to deliver you one point your actually doing 1000 times the computation you actually need to get the result. So all of this si pretty fine IF you can ask for some very isolated part of the dg but if you ask one vertex then you are eating much more than is probably needed. That is UNLESS you need ALL the points at that different time.