tangent manipulator behavior

Evan_Reese

I'm trying to work out a way to make a point on a curve with a linear manipulator (inspired by the new Loft connections). My thought process has been:

1. measure the curve.
2. divide 1 by the curve length to make the manipulator offset distance correspond to the new parameter value needed to move along the curve.
3. use a clamp() function to limit the values from 0 to 1 for the parameter

I still seem to be getting values jumping around a lot. I put together an example of what I'm trying to do. Any input is appreciated. Am I close?
https://cad.onshape.com/documents/8f9ced588efde6aeb961179b/w/82fc597da85b474ebe34145b/e/0e2af702f669ec1a43004265

ilya_baran

This is a simplified example of how the loft one works: https://cad.onshape.com/documents/f82d32555cb582eb811edaa4/v/817dfeb6795b514c82f56edd/e/1c59b56b02f636d764721c18

ilya_baran

This is a simplified example of how the loft one works: https://cad.onshape.com/documents/f82d32555cb582eb811edaa4/v/817dfeb6795b514c82f56edd/e/1c59b56b02f636d764721c18

Evan_Reese

Thanks @ilya_baran
I like this approach much more than mine (surprise surprise ). You're just figuring out where the new manipulator would be, then snapping it to the closest spot on the curve, right? I haven't messed with DistanceResult at all, and I'll have to play with it to understand how to use the parameters there.

This is actually a great step toward solving another issue further down on my list. You may have guessed I'm working to add curves as a reference option for Freeform Spline since it would make it so much more useful for surface modeling. I'd like to make a change function that snaps the point to the closest point on the reference curve when it is selected (rather than defaulting to a parameter of 0.5, which would feel jumpy most times). This seems like it might work for that too.

Thanks!

Evan_Reese

@ilya_baran
I'm getting some weird behavior from your example, my Freeform Spline feature, and the Loft connections when using certain edges as references. Any idea why the edge type would matter? See below. The first example is a loft between two solid body edges, and the connections have trouble. But if I use Fit Spline on the edges, and loft between the splines, it seems ok, even though the resulting geometry is nearly identical.

Evan_Reese

here's the one lofted between fit splines instead. it works much better

ilya_baran

@Evan_Reese can you post a link to a public document version with the bad behavior so I (or someone else) can take a look?

Evan_Reese

ilya_baran said:

@Evan_Reese can you post a link to a public document version with the bad behavior so I (or someone else) can take a look?

I hindsight I should have lead with that

https://cad.onshape.com/documents/627921b62c5d8c4a56037b12/w/a9c16309dec5ac1100147873/e/fb5201dd1135a895113e01ea

I put a few examples of features with edges for references that don't do so well, and features where the same edges have been produces with Fit Spline that work as expected.

ilya_baran

Looks like a bug -- thanks for reporting.  We'll investigate when we get a chance.

Evan_Reese

ilya_baran said:

Looks like a bug -- thanks for reporting.  We'll investigate when we get a chance.

Thanks, Ilya.

Henk_de_Vlaam

ilya_baran said:

Looks like a bug -- thanks for reporting.  We'll investigate when we get a chance.

  

Evan_Reese

Henk_de_Vlaam said:

ilya_baran said:

Looks like a bug -- thanks for reporting.  We'll investigate when we get a chance.

  

Thanks to @Henk_de_Vlaam for pointing it out to me in Freeform Spline which made me dig a bit and find it.