how to use mirrorAcross

papawo

Jake_Rosenfeld

You can mirror across any planar face, so if the part you're mirroring has a good face for that, you can just use that face.

Otherwise, if you have the mathematical description for the plane you want to mirror across, but no actual geometry for it, you can do something like:

var mPlane = plane(vector(1, 2, 3) * inch, vector(1, 0, 0)); // <-- just an example, use any plane you want
opPlane(context, id + "plane", { "plane" : mPlane }); // <-- creates the construction plane<br>mirror(...); // <-- do the mirror using qCreatedBy(id + "plane", EntityType.FACE) as the `mirrorPlane`

opDeleteBodies(context, id + "delete", { "entities" : qCreatedBy(id + "plane", EntityType.BODY) }); // <-- delete the plane so it is not left behind in the Part Studio

https://cad.onshape.com/FsDoc/library.html#plane-Vector-Vector
https://cad.onshape.com/FsDoc/library.html#opPlane-Context-Id-map
https://cad.onshape.com/FsDoc/library.html#opDeleteBodies-Context-Id-map

Jake_Rosenfeld

What are you hoping to accomplish?

Calling mirrorAcross returns a 'Transform' which can be used in a variety of ways. A few examples: a transform could be used in applyPattern() to mirror a part or it can be multiplied by a  world space 'Vector' to mirror that vector across the plane in question.
https://cad.onshape.com/FsDoc/library.html#module-transform.fs

The concept is similar to a transformation matrix in linear algebra:
https://en.wikipedia.org/wiki/Transformation_matrix

papawo

i just want to do this. 

Jake_Rosenfeld

You can use the 'mirror' feature:

mirror(context, id + "mirror", {
        "patternType" : MirrorType.PART,
        "entities" : a query for the part you want to mirror,
        "mirrorPlane" : a query for a face you want to mirror across.  In this case you could use qCreatedBy(makeId("Front"), EntityType.FACE) to get the front plane,
        "operationType" : NewBodyOperationType.ADD,  <-- same as "Add" in the feature dialog
        "defaultScope" : false, <-- same as turning off "Merge with all" in the feauture dialog
        "booleanScope" a query for what you want the result to boolean onto <-- same as "Merge scope" in the feature dialog
    })

If you don't want to boolean the result onto the seed, you can just leave out the last 3 parameters.

papawo

What if the “front plane” doesnt exist?
how to create or get that plane without user selecting the face?

Jake_Rosenfeld

You can mirror across any planar face, so if the part you're mirroring has a good face for that, you can just use that face.

Otherwise, if you have the mathematical description for the plane you want to mirror across, but no actual geometry for it, you can do something like:

var mPlane = plane(vector(1, 2, 3) * inch, vector(1, 0, 0)); // <-- just an example, use any plane you want
opPlane(context, id + "plane", { "plane" : mPlane }); // <-- creates the construction plane<br>mirror(...); // <-- do the mirror using qCreatedBy(id + "plane", EntityType.FACE) as the `mirrorPlane`

opDeleteBodies(context, id + "delete", { "entities" : qCreatedBy(id + "plane", EntityType.BODY) }); // <-- delete the plane so it is not left behind in the Part Studio

https://cad.onshape.com/FsDoc/library.html#plane-Vector-Vector
https://cad.onshape.com/FsDoc/library.html#opPlane-Context-Id-map
https://cad.onshape.com/FsDoc/library.html#opDeleteBodies-Context-Id-map

papawo

thanks, I think I can work on that.