Create a variance on a face with opExtrude?

daniel_cravens

What is the best way to create a variance on face? My thought is simply to reduce the part with opExtrude by the variance amount (i.e. 1 mm) + opBoolean (subtract) to cut the 1 mm variance from the part.  However, my problem is that I cannot figure out how to determine the correct direction for the opExtrude from the face once I calculate the normal. I can calculate the normal from the face (see below), but that doesn't tell me whether the cut should be in the normal direction or the anti-normal direction in order to reduce the part. What am I misunderstanding?

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export function evFaceNormal(context, qface is Query) returns Vector

{

      

    var plane = evPlane(context, {

            "face" : qface

    });

    return plane.normal;

}

NeilCooke

If you are removing material you want to extrude in the opposite direction. You may also want to check opMoveFace.

daniel_cravens

Thank you! OpOffsetFace with a negative offset did the trick. I'm still getting the hang of feature script and really appreciate the support!

        var cutFaces = qCreatedBy(id + "cutFemale", EntityType.FACE);

        opOffsetFace(context, id + "offsetFace1", {

                "moveFaces" : cutFaces,

                "offsetDistance" : -.1 * millimeter

        });

daniel_cravens

As a follow up, although opoffsetface solved my problem for this feature. I'm still curious about how to arrive at the general solution. If I have a face, how can I determine programmatically which blind extrude direction will remove material and which will add material? Is it as simple as a negative number will always remove material?

NeilCooke

Face normal always points outwards so make it bigger is positive and make it smaller is negative. 

daniel_cravens

Awesome. That is easy enough.