unpredictable plane rotations along a curve

Hi guys,

I'm trying to move a plane along a curve using a 2 pt vector, and the orientation of the plane keeps shifting/rotating about the axis unpredictably.

I used evaluate curve, and input a fader into the t input so that the two points were constantly shifting up the line. Is there a way of creating a normal or tangent that keeps the plane oriented in one direction?

The file is included, bright blue panel is where the plane function is. The rest of the code is rotating 7 points in a helix about the line, while projecting to the moving plane. The unexpected rotations are giving my helix tight turning points that are messing with the aesthetic!

Any help you can give is much appreciated.

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Permalink Reply by Hannes Löschke on February 13, 2013 at 2:00am

A normal and point are not sufficient to define a plane in 3D space. Rhino/GH needs to do some guessing for the second vector.

You should use PerpFrames. This creates planes along a curve oriented by tangent and maximum curvature.

Permalink Reply by Liam Dewhurst on February 13, 2013 at 5:35am

Genius! Thanks for the help, I couldn't think of the right way to approach anchoring the plane to the line.

If you have any ideas about how to make logging information less intensive I would love to know as well. At the moment my machine struggles when I make the code live. Saving the information to a location has helped the process but I get the feeling there is more that can be done??

This is for a project using kinect, skeletal motion tracking a line from the right hand that will (hopefully) be transformed into a weaved form of clothing and will be projected onto a scanned human form and then relayed back in real time. Any processing delay in the coding is going to alter the experience to a degree.

Permalink Reply by Hannes Löschke on February 13, 2013 at 12:30pm

Weeell... there really isn't too much you can do about speed except keeping your definition as light as possible, turn off all preview geometry and stick to pure math as long as you can. Problem is GH running on a single thread only. Depending on your CPU and power saving settings this will kick you back about ten years in CPU development.

GH might have all those nice interfaces and be easy to code but it was never meant to do anything close to realtime.

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