Find minimum radius of curve with FeatureScript?

EvanReese

I looked through the documentation for a function that would return the minimum radius of a curve and didn't see anything that would. I'm looking for the same minimum radius value that's given by the show curvature dialogue. Am I missing an existing function for this, or do I need to do some kind of iterative sampling to check the curve at a bunch of places and return the min radius I find?

Jacob_Corder

@Evan_Reese
Nope. no built in function.
Solidworks has one, which likely means parasolid does also and onshape is holding out on us (joking guys) 

I am just guessing here, but this might give you a start.

extract the b spline curve using evApproximateBSplineCurve  then read this crazyness and see if section 2.1 Smoothness measure section will help.
I have been meaning to do this myself but just haven't gotten to it.
https://www.diva-portal.org/smash/get/diva2:996026/FULLTEXT01

The reason you would want to use the b spline curve is because then you are not guessing at how much to approximate the curve which could take a huge amount of time and also you would never find that minimum curvature point when guessing. you could get very very close but never totally get it. 

NeilCooke

Sample the curve using evEdgeCurvatures and radius at each point is 1 / curvature

EvanReese

@NeilCooke and @Jacob_Corder

Thanks. That's what I was afraid of. I hoped that since the Show Curvature tool does it well there might already be a function for it. If I go the sample route, I may even do it in two phases: one coarse pass on the whole curve to find the area that's likely to have the most curvature, then a second set of samples right around that area to refine the result, but it's definitely less simple that just typing evMinimumRadius().

Jacob_Corder

@Evan_Reese
I tried to see if it was a hidden call somewhere in the @darkSide of onshape, but i couldn't get a match with many tries.(@evMinimumRadius, @evMinimumCurvature .....).
 evMinimumRadius would be great. 

Also, Evan, if you are going to be calling evEdgeCurvatures, it is significantly faster to call @evEdgeCurvatures because building the frames and data and storing them into maps of types is actually a lot more time consuming that you would imagine. using the raw numbers is faster to get, faster to evaluate because ValueWithUnits is removed and vector removed. I have seen it cut the time by half in a thickness analysis feature I wrote, and at least cut in half for an edge tangency checking feature that I wrote. I couldn't believe how long it took to convert from normal numbers to the structures we use (vector, line,plane,....).