Vertex attributes

[dannyst]

Is there any way to get access to the x,y,z attributes of a vertex? I can use listAttr on a vert and I get somethign like:

// Result: pnts[50] pnts[50].pntx pnts[50].pnty pnts[50].pntz //

However I cannot find any way to get to the attribute.

Also, I know I have seen it around before, but I can't find it and can't remember how to do it. Using connect attr, I need to know how to connect an attribute to another, but have the influence be say 50%. So if I move object A in x, object b moves half as far in x.

[macaronikazoo]

the getAttr on a point should work just fine... the only problem is, is that those x,y,z values stored in the pnts[50].pntx attrib are relative values. to get world space values, i think you have to use the xform command.

as for the connectAttr only having a 50% influence, you'll have to run it through a multiply/divide node. i'm not aware of any way to make a connection divide itself in half...

[dannyst]

Thanks for the response. I don't need the coordinates really. What I need is access to manipulate the attributes of a vertex via connectAttr.

I have tried the following ideas to get to the x y and z attributes of a vertex

getAttr pnts[3].x
getAttr pSphere1.vtx[3].pnts[3].x
getAttr PSphere1.pnts[3].x

I figure that if I can get the getAttr command to work, then I can use the same idea to connect the attribute. I just can't figure out how Maya wants the attribute given to it to give me access to it.

[joojaa]

ok youre missing on fundamental maya thing. The shape isnt stored in the transform its justa container for the transform, its under this in a separate node called the shape. The points themselves are stored in the shape. Now going back to your listAttr wich shows the correct names, but you assume the wrong parent. So...

getAttr pSphereShape1.pnts[50].pnty

Would be correct, unless you have changed the deafult naming convention. Remeber on polys this is a relative value from the poisition of the point whare it was created on! So your answer in a un modified sphere would be 0.

[strarup]

Hi danny,

eh... if you just want the value of the x,y,z from the vertex, you can use the pointPosition command

e.g. if it is for Vertex number 50 of the sphere it could be like this... -->
pointPosition pSphere1.vtx[50];
or
pointPosition pSphere1.pnts[50];

unfortunately I don't know how to separete the pointPosition command yet...

however you can also use the xform command with a worldspace flag...
xform -ws -q -t pSphere1.pnts[50];
(gives you the same result as above)....

see more about it here... -->
http://www.ewertb.com/maya/mel/mel\_a06.html

if you e.g. want the x,y and z "apart" from eachother, you can make a float array (see bottom of the site)...

I played a bit with it...
float $coords[] = xform -ws -q -t pSphere1.pnts[50];
print("// x= "+$coords[0]+" // n");
print("// y= "+$coords[1]+" // n");
print("// z= "+$coords[2]+" // n");

I don't know if this can help you further... but I hope it can...

regards

Strarup

[user_deleted]

I was lookin for an answer to this one for a while. It's in the docs under "polygon limitations"

"cp attribute limitation
On polygonal objects, the cp attribute is supposed to represent the actual position in local space of a vertex, while the pnts attribute represents the tweak value (its offset relative to the rest position).
The cp attribute is a compound attribute with child attributes named xv/yv/zv. When you get the value of the parent attribute, Maya incorrectly returns the same value as for the pnts attribute."

Use the xv/yv/zv child attributes individually instead of the entire cp compound attribute.
For example:
polyCube; select -r pCube1.vtx[0] ; move -r .1 .1 .1;
getAttr pCube1.cp[0];
// Result: 0.1 0.1 0.1 //
getAttr pCube1.cp[0].xv;
// Result: -0.4 // Real X position (-.5 + .1)

[joojaa]

wat kind of limiatation is it that ou have bothe value and tweak on top of that. its actualy a super usefull boon when you need to collapse history on top of yoru old history.