generative modeling for Rhino
How to move a point along a curve with a certain distance
Hi,
I created a closed planar curve and have a set of t paramets, that define points on that curve. I would like to move the points all about 15 units along the curve to the right.
I tried the shift component, but it didn't work because the points are not equally distributed.
Q: How can I move a point, that lies on a curve a certain distance along the curve. (Also, if the curve is closed, how can I manage, that the point also moves from the end back to the beginning e.g. moving the t value from 0.9 to 0.1)
Thanks in advance for your Help.
Martin
I created a closed planar curve and have a set of t paramets, that define points on that curve. I would like to move the points all about 15 units along the curve to the right.
I tried the shift component, but it didn't work because the points are not equally distributed.
Q: How can I move a point, that lies on a curve a certain distance along the curve. (Also, if the curve is closed, how can I manage, that the point also moves from the end back to the beginning e.g. moving the t value from 0.9 to 0.1)
Thanks in advance for your Help.
Martin
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example1.jpg, 481 KB
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Replies to This Discussion
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Permalink Reply by °[u on -
Hi Martin,
i'm not sure if i understood you problem...
you should try this: right cklick on the CRV container -> Reparameterize
or do you really want to move from 0.9 to 0.1 (=1.1 > 1) ?
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Permalink Reply by Martin Manegold on -
Hi,
here are the files, I'm working with right now.
Maybe it is easier to illustrate the problem.
I want to move the points on the top line x units to the right, so that the lines are tilted.
How do I move the points?
- About this 0.9 to 0.1
If a curve's parameters go from 0 to 1 and the curve is closed, then the point with the parameter 0 and the point with the parameter 1 are identical.
So
If I move the Point with the t-value of 0.1 up by the 0.2 the new value is 0.3.
If I move the Point with the t-value of 0.9 up by the 0.2 the new value is supposed to be 0.1 - because it goes in a circle. But it returns 1.1, which is not a parameter on the curve anymore. - Attachments:
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090618_example1.3dm, 74 KB -
090618_example1.ghx, 317 KB
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Permalink Reply by °[u on
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- Attachments:
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090619_move_points_on_curve.ghx, 394 KB
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Permalink Reply by Martin Manegold on
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Hi,
That is great. I never really knew what this dispatch and merge really were for. Thanks.
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But I still have a little problem with the distance between the points. If I add the same number to each parameter, the distance between the points is not exactly the same.
So I need to somehow calculate the t value, that is exactly x units to the left of the point. (which is probably different for each t- parameter).
I was wondering if there is an easy way to calculate that. (I haven't found one, yet)
What I need is basically the opposite of the "evaluatelength" component. You input a curve, a starting point and a lenght and get out a new t-parameter.
I could think of a workaround for my Problem by dividing the curve in x-times as many pointsthan I need and the filter out the shifted points, but I'd rather not do that :-)
Martin
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