Simply Maya User Community - View Single Post - NURBS reversing direction when transformed

I've made some progress on this. I've written an expression that gets the positions of the two cvs and controls the rotation of the nurbs circle.

Code:

//get world space positions of the CVs
vector $pos1 = `xform -q -t -ws curve1.cv[0]`;
vector $pos2 = `xform -q -t -ws curve1.cv[1]`;
vector $newVec = $pos2 - $pos1;

//calculate rotation
$rotation = `angleBetween -euler -v1 0.0 1.0 0.0 -v2 ($newVec.x) ($newVec.y) ($newVec.z)`;

//set rotation of nurbs circle
nurbsCircle1.rotateX = $rotation[0];
nurbsCircle1.rotateY = $rotation[1];
nurbsCircle1.rotateZ = $rotation[2];

It seems to work okay, aside from a weird error

Code:

Error: line 1: No object matches name: curve1.cv[0]

It's weird because the expression works. If I put a cluster deformer on the CV and animate its position, the nurbs circle will rotate. So far this only works with the circle lying flat (facing the y axis). I'm sure it could be made more robust. Now to see if it keeps the normals facing the right way!