Welcome to the Onshape forum! Ask questions and join in the discussions about everything Onshape.
First time visiting? Here are some places to start: Looking for a certain topic? Check out the categories filter or use Search (upper right).
 Need support? Ask a question to our Community Support category.
 Please submit support tickets for bugs but you can request improvements in the Product Feedback category.
 Be respectful, on topic and if you see a problem, Flag it.
If you would like to contact our Community Manager personally, feel free to send a private message or an email.
Distance constraint parameters
I notice that distance constraints seem to either have "halfSpace0/1" parameters or alternatively an "alignment" parameter. What is the difference in use cases between these?
I realize that sketch constraints are considered internal, but any clarification would be appreciated.
I realize that sketch constraints are considered internal, but any clarification would be appreciated.
Tagged:
0
Best Answer

paul_chastell Posts: 117Simple explanation is that it is all about distinguishing between two different cases. Take a line. Constrain one end to the origin. Add an angle dimension to a horizontal construction line. Add a point with a distance dimension to the line. See example pic below.
Change the angle dimension by a large amount so that if the point didn't have a dimension it would be on the other side of the line. It stays on the "correct" side instead, or at least on the side that most people using Onshape would expect it to be on.
It is the halfspace parameter in that case that helps the sketch do the right thing. A point on the other side of the line with the same dimension would have a different halfspace value. Note that this is not the same thing as negative values, instead it tells the sketcher which direction is positive. Alignment is different but does a similar job.
Paul Chastell / VP of R&D / Onshape Inc.6
Answers
Change the angle dimension by a large amount so that if the point didn't have a dimension it would be on the other side of the line. It stays on the "correct" side instead, or at least on the side that most people using Onshape would expect it to be on.
It is the halfspace parameter in that case that helps the sketch do the right thing. A point on the other side of the line with the same dimension would have a different halfspace value. Note that this is not the same thing as negative values, instead it tells the sketcher which direction is positive. Alignment is different but does a similar job.