Interpolating a curve

I created a gh file with an ellipse with an axis line and tangent line at the end. I set up a recorder for the starting point of the tangent line. I then take an interpolated curve and polyline component to trace the point collection. (I internalized the points to the interpolated curve and the polyline.)

For some reason the interpolated curve doesn't draw, but the polyline does. Can someone give me a clue as to why the interpolated curve doesn't work?

Attachments:

Interpolating a curve.gh, 8 KB

Replies to This Discussion

Permalink Reply by Chris Tietjen on November 11, 2012 at 10:56am

I didn't have any problem with the interpolated curve but the polyline wouldn't draw. It looks like duplicate points needed to be removed.

Permalink Reply by Norm Sash on November 11, 2012 at 12:11pm

Thanks Chris... that seemed to solve the problem of not displaying the interpolated curve... I'll have to remember that one... did you just "know that"?

Second quick question I hope... the curve isn't drawn correctly for me and I think it is because the points aren't in the right order (?). But when I sort the list it is converted into something else than vertices. What would you used to make sure the list is in correct order?

Permalink Reply by Chris Tietjen on November 11, 2012 at 3:46pm

The polyline component was remaining orange so I looked at it's 'error' message which indicated that there were zero length line segments. In general though if a component that takes a list of points isn't working then there's something wrong regarding the list. Then it's either something regarding the branching (tree structure) or something regarding the items themselves.

I'm not understanding why your points aren't in the correct order? Are you sweeping the ellipse in one continuous 360 degree motion when you record the list? If not this could make the difference.

Permalink Reply by Norm Sash on November 12, 2012 at 10:39am

Yes, I was sweeping the ellipse from 0-360 and then 360-0... I figured that would give me more points to create a curve through and would increase the accuracy of the curve. So then my problem is how to sort the points so that they would be sequential (e.g. arranged closest point going clockwise.) Is there a way to force the curve to be interpolated through the next closest point?

Permalink Reply by Norm Sash on November 12, 2012 at 10:44am

I've enhanced the gh file and now am generating the line and tangent line a little differently. Now I'm running into a problem interpolating the curve through the set of generated points if the number of divisions of the ellipse goes to 40 (dividing a 360 degree curve into 40 sampling divisions. Ten divisions works fine, 20 divisions works fine, buy 40 divisions causes a "loopback" in the interpolated curve. Any ideas why? I've attached video and a new gh file.

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