Generate curves between 2 curves

Replies to This Discussion

Permalink Reply by Ethan Gross on September 28, 2017 at 12:26pm

Curves->Spline->Tween Curves, where the factor F (0 to 1) determines the degree of interpolation between A and B.

Permalink Reply by Igor Kozyrev on September 28, 2017 at 12:50pm

I've tried tween curve, but

1)I have some weird interpolating curve (see screengrab below)

2) what if i want to generate more than 1 curve? Let's say i want to regulate number of curves with slider..

Permalink Reply by Michael Pryor on September 28, 2017 at 12:56pm

I cant see the screenshot, GH forum images seem to be loading only partially (at least for me) however with tween just give it more factor values to get more tweens. 

Edit: now I can see it

Permalink Reply by Igor Kozyrev on September 28, 2017 at 1:02pm

ok, still having weird interpolation issues

Permalink Reply by Michael Pryor on September 28, 2017 at 1:10pm

Ok here are your issues, there are two. First issue is your seams. Tweens in rhino and GH work by matching points (in GH case it uses the iso of a ruled surface between curve A and B to handle many cases like when curves have discontinuities) 

So first problem, your seams most likely don't align, you can check where the seams are with the adjust seam component, to fix this either rotate your curves so that the existing seams line up, or change the seam location with the seam component. 

Permalink Reply by Michael Pryor on September 28, 2017 at 1:20pm

Second problem, large deviation in number of control points between two curves (specifically when tweening circles/arcs/ellipses to other drawn curves). The ruled surface or connection between the two curves is dependant on control points and the curve. The problem with circles/arcs/ellipses is that they are made differently than other nurbs, they have less control points but use varied weights to make the shape, this is to not have to use 2000xxx points to make a "perfect circle" (look at the control point polygon of a circle it has only 8 points, the corners are weighted differently.) So here you are trying to tween essentially 8 control points to however many are in the outer curve (this also destroys the structure of the weighted circle, hence the weird looking shape)

The fix, run your curves in this case each through a fit curve component. This fits a new curve through an existing curve via control point and curvature info of the input curve while maintaining the shape.  This will get you a better distributed tween. 

Permalink Reply by Igor Kozyrev on September 28, 2017 at 1:31pm

thank you!

it worked!