Problem rotating point along curve?

Hi everyone!

I'm having trouble rotating a point as illustrated below:

I managed derive an angle based on two vectors, though unfortunately, once I plug it into my rotate component, it doesn't seem to rotate right.

I'm reasonably assured that my axis and centrepoint are right. So I'm not too sure what the problem is. Could it be the direction of the vectors affecting this?

Would be great if someone could have a look at my grasshopper file and rhino file! Any advice or suggestions would be appreciated :)

Thanks in advance!

Attachments:

help.ghx, 1.5 MB
help.3dm, 60 KB

Replies to This Discussion

Permalink Reply by Ángel Linares on May 23, 2010 at 5:10am

I think that this could be something about curve torsion. Curves perpendicular frame could rotate around tangent vector in some situations.

Indeed, tangency in two curves with this kind of rotation doesn't meet keepping same seeming tangent line.

Best Regards.

Permalink Reply by Ra on May 23, 2010 at 5:46am

Thanks for your input, Angel.

Sorry but I'm not quite sure what you are talking about. I understand that you are saying that the curve might be torqing. But I don't really understand the whole curves perpendicular frame thing. If it isn't too troublesome, could you add more detail about that?

Permalink Reply by Ángel Linares on May 23, 2010 at 7:46am

If curves are torquing then perp frames must be rotated.

But your mistakes is not tere; it is in the Rotation Axis that you use. It's not correct i think. If you move the point up and then use the line that connect new point with the old one, you obtain the same point. Your rotation axis is the tangent line to the main curve at first point position.

Hope this helps ;)

Permalink Reply by Ra on May 23, 2010 at 8:05am

I think I understand. So I tried plugging in PFrames into my function. Is there a way of viewing frames? Would I have to plug this back into my points? I don't want my points to be equally spaced though.

Actually I tried that but this time, the point stayed in it's same position! Very strange.

Thanks for your patience!

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