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# How to do a simple rotation of cylinder around center point after a move?

Member Posts: 3
Hello!

I am pretty new to featurescript (though I am a software engineer in my day job). I have been able to do some of the basics like making a drawing plane, extruding the plane and moving bodies around but I can't seem to figure out how to do a basic rotation of a cylindrical body I have created. This seems like it should be a pretty simple thing to do so I am guessing I must be missing something!

The only example I can find seems to rotate the body around an axis relative to the world, not relative to itself. I basically just want to "spin" the object without having the object change position. Is there an example of this someone could point me towards?

Thank you!

• Moderator, Onshape Employees Posts: 3,273
Take a look at rotationAround which takes a line (the cylinder axis), then use opTransform
• Member Posts: 3
Thanks for the response! I did take a look at that, particularly this forum post:
https://forum.onshape.com/discussion/3590/transform-rotate-around-axis
So I guess my question is, how do I get the center line of the object? I tried creating a plan on the top face of the cylinder using evPlane and using the origin/normal to create the line to pass into rotationAround but that does not seem to be doing what I want.
In the forum post I linked to they show creating the line to rotate around like this:
`const zAxis = line(vector(0, 0, 0) * meter, vector(0, 0, 1));`
Is the line created by this set to 0,0,0 of the world or 0,0,0 of the plane? Using rotationAround I am able to rotate the object it just doesn't seem to be around the center line as the object moves as well as rotates.
Thanks again!
• Moderator, Onshape Employees Posts: 3,273
```    precondition
{
annotation { "Name" : "Cylinder", "Filter" : EntityType.FACE && GeometryType.CYLINDER, "MaxNumberOfPicks" : 1 }
definition.cyl is Query;

annotation { "Name" : "Angle" }
isAngle(definition.angle, ANGLE_360_BOUNDS);
}
{
var axis = evAxis(context, { "axis" : definition.cyl });

var angle = rotationAround(axis, definition.angle);

opTransform(context, id + "rotate", {
"bodies" : qOwnerBody(definition.cyl),
"transform" : angle });
});```

• Member Posts: 28 ✭✭
I leave here a complete test of:
NeilCooke said:
```    precondition
{
annotation { "Name" : "Cylinder", "Filter" : EntityType.FACE && GeometryType.CYLINDER, "MaxNumberOfPicks" : 1 }
definition.cyl is Query;

annotation { "Name" : "Angle" }
isAngle(definition.angle, ANGLE_360_BOUNDS);
}
{
var axis = evAxis(context, { "axis" : definition.cyl });

var angle = rotationAround(axis, definition.angle);

opTransform(context, id + "rotate", {
"bodies" : qOwnerBody(definition.cyl),
"transform" : angle });
});```