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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.
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paul_chastell
Onshape Employees Posts: 124 
Simple 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
TVP, Onshape R&D6
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.
TVP, Onshape R&D