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Rotating a sketch rectangle
graham_lock
Member Posts: 227 PRO
Hi,
I'm drawing a rectangle which I want to rotate:
I have a rotation transform matrix where the angle is user driven:
var rotationMatrixStart = [[cos(definition.freeXYStartRotation), -sin(definition.freeXYStartRotation)], [sin(definition.freeXYStartRotation), cos(definition.freeXYStartRotation)]] as Matrix;
And a sketch:
skPolyline(sketchStartFormer, "profileStartFormer", {
"points" : [
startProfileCorner1,
startProfileCorner2,
startProfileCorner3,
startProfileCorner4,
startProfileCorner1
]
});
How should I go about rotating the rectangle about its centre point to achieve the equivalent of:
If I apply the rotation to the points before sketching them then the rectangle rotates about the centre of the sketch plane.
Any help appreciated.
Thank you.
Answers
removed
Thank you but I need to do this in Feature Script.
Does this help?
https://cad.onshape.com/documents/164c09de99073544524150c2/w/95e2fe023391a43f159891ac/e/af7550ab2e2d704f6e3c7c38
Thank you.
So if I'm understanding this correctly, when using Sketcher it's possible to transform around the centre of a sketched area, but in Feature Script there is no such transform available so the sketch plane centre needs to be at the centre of rotation of the area to rotate?
There isn't anything like a skTransform function (at least not one that's publically documented). When making sketches in FS, it's more important that you get your initial coordinate system correct, instead of creating a sketch somewhere and then moving it. That's part of the reason that the sketch documentation says constraints are mostly unnecessary when sketching in FS, you can usually pinpoint exactly where you want it with some good vector math. Another approach could be to sketch and extrude, then do the opTransform function (this depends on the use case of course).
If you want my advice though, I would recommend staying away from sketching in FS. What I do almost every time I need sketches generated by a custom feature is I make a part studio with that sketch in it, set it up with configuration parameters, then I just derive the sketch in using the custom feature and from there it's much easier to place/rotate the sketch entity. It's also way easier to edit that sketch since you can just edit it in a part studio instead of redoing your logic for constraints in FS.
chadstoltzfus@premiercb.com
Thank you.
How do you derive the sketch into a custom feature and then set the configuration parameters?
in my use case the final part is a loft between two sketch profiles. The user selects the profiles shapes / sizes, x/y offsets and rotation in the feature UI.
Would that be possible with your recommendation?
Thanks again.
It's been a while since I've taken linear algebra, but I think you can rotate about an arbitrary point. Translate → Rotate → Translate back.
Interesting thank you.
Here's a really simple example. It was made for a different post on this forum but I commented the code you'd be using to import sketches. You're pretty much just using the instantiate function, there's plenty of documentation on that here.
https://cad.onshape.com/documents/cec79d6de564717d83526a2b/w/6552169cf2769c6c4135d9f1/e/3a971c226d00e7eb7c24e3bd
This is a pretty widely applicable technique. Pretty much any time you need a sketch you can do this instead. This also works just fine with imported parts as well, so there are times where I don't want to make complex geometry in a custom feature so I'll do the same thing and just configure a part and import that in using the same technique.
chadstoltzfus@premiercb.com
Thank you.
I've tried to recreate this document since it is read only but I get:
IMPORT_DERIVED_NO_PARTS
My test document is here:
https://cad.onshape.com/documents/4dea6a14a5bba4a6744c3fe9/w/5d36b22c3c19762fd239743b/e/ba32108e071585a347d97118
Your "partQuery" is for solid parts (qBodyType with BodyType.SOLID), which you won't have in your part studio. qEverything(EntityType.BODY) should be sufficient for deriving a sketch.
FRC Design Mentor - Team 1306 BadgerBots
Thank you, this gets past the derived parts error but then the boolean fails with:
BOOLEAN_INPUTS_NOT_SOLID
I don't think you can boolean a sketch and a solid.
Thank you. Yes, I'm confused as the document which @chadstoltzfus linked to above appears to work.
Sorry, forgot that I extruded something in the Sketch Config part studio, so pretty much the instantiator is bringing in the extrude part and booleaning it. But you can more or less use the same technique to import a sketch. If you comment out the opBoolean() in your document you should see that the sketch has been brought over successfully.
chadstoltzfus@premiercb.com
Ok thank you- I’ll have a play.