Perp frames does not work with points on curve


why can I not use “points on curve” together with “perpendicular frames” to establish perpendicular frames at points on a circle which are defined with “points on curve”?

As you can see, other frames accept the points on curve slider.

why not perp frames?

what must I do or what is my mistake?

Reparametrize the Curve input or use closest point to curve component to find correct T parameter of the curve.

What @Petras_Vestartas said.

Point On Curve outputs a point, not a ‘t’ parameter. Construct Plane ‘O’ (Origin) accepts a point but Perp Frame ‘t’ (Parameter) does not. It accepts a numeric value corresponding to the position on the curve, which may be a number between 0 and 1 if the curve is reparametrized.

so how can i get a plane on the points generatet with points on curve that are perpendicular?

It is important for me in this case that I can adjust or fix the planes at the top, bottom and all other points on the circle and that the points stay at these position when I change the diameter of the circle.

Ok,… found it


The code I posted does exactly that. You can add Deconstruct Plane (DePlane) to see the points for each frame.

Or if you insist on using Point On Curve, you can do as @Petras_Vestartas described and use Crv CP to get the ‘t’ parameter values, with or without reparameterizing the curve. (7.4 KB) (7.4 KB)

If you had posted a GH file I would have posted my GH files in reply…

Many thx,… I will try it out.

Do you know if there’s any kind of manual or handbook that explains every function/item of grasshopper how it works and which kind of data it needs to work properly? The explanations in the „help“ sections are much to short for me to understand it for me.

There may be, I don’t know. Every component input reveals its expected data type when you hover the mouse over it.

I just noticed that I posted GH files despite my intention not to… habit. (7.0 KB)

I suggest you get in the habit of posting a GH file when you start a thread. And reading other people’s code in threads you don’t create is an excellent way to learn. The forum search feature (or Google) will lead you to examples for specific components.

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me again,

Parametrischer Ring mit (14.8 KB)

I did like you told :wink:

but now,… i don’t understand, why the last line shows such a strange behaviour. It should just stay at the same plane and direction as the other line, but it doesn’t.

but why?

I see nothing wrong with the pFrames in your model so don’t know what you mean by “strange behaviour”?

the perpframes are fine now.

I am talking about the last line at the end of the one perp frame. It has changed in the z-axis and I don’t know why. it should stay at the same frame like the other line that starts at the circle.

Maybe because you have wired a Unit X vector to the ‘Geometry’ input of Move?

Computers do what they are told. Be more careful with your instructions!