Solved! Go to Solution.
I would not recommend that working method.
Much better to work with splines outside of the sketcher. Use the Studio Spline constraint functions.
Yes, splines outside of the sketcher are very robust choice. But I must say that, the temptation of the flexibility, of constraining poles to control the spline shape in sketcher, is really difficult to resist.
One thing that might help is this:
The spline can create a G2 constraint, but there is an additional part in the dialog to this that constraints the spline even further. You can set the tangent magnitude and lock it. This constraints two DOF's (degree of freedom) on the first pole completely and one DOF on the second pole.
See movie below.
This might not solve your problem, but maybe this tip gives you new ideas on how to constrain the splines in sketcher.
The other value overwrites the radius size that was inferred from the arc with a fixed value. You probably do not want to toggle that on.
There is a fairly simple formula for the curvature of a Bezier curve at an end-point. For example, see formula (2.13) in http://cagd.cs.byu.edu/~557/text/ch2.pdf.
Geometrically, this formula is a statement about certain lengths and distances, so conceivably you could use it to concoct suitable constraints on the curve poles.
However, this doesn't seem like a very good approach, to me.
Hi @DickBaardse Thanks a lot for your tips and information!
The formula (2.13) for calculating the curvature at a point on a spline is exactly what I'm looking for.
As you said, it is not a very good approach. However, when you have a big model and need to add a G2 constraint to a spline in sketch, to constrain the poles seems to be the only choice. In my experience, to click open and edit an exising spline would destroy some consraints and lead to disaster for the whole model.
Following the reference you cited, the curvature radius at a spline point can be calculated as shown below. Very good!