I am new to grasshopper and I am looking for some help to build a curve similar to the photos I have attached. These photos I have easily made using Rhino. With grasshopper I was able to parametrize the points on the circumference by dividing into angles and finding connecting intersections. Now my question is how to move up and down with positive and negative values( z axis) the points in a specific dimension size and find the same points that I had found with rhino. I want to interpolate the points and have the same curve as if doing it by hand. I tried to find the mathematical function but I donāt know if this is the right way to go about this. Do you have any other strategies for me? thanks so much for your help.
This is the right way. Then use Series or Range components along with Expression component where you type in your equation (math function)
sinusoid.gh (12.8 KB)
Thanks for your reply, I tried to go ahead with the algorithm but its always similar but not exactly the same. Can you help me? thanks sinusoid.gh (11.8 KB)
By helping do you mean solve it instead of you?
It doesnāt work like this, sorry.
I gave you a start develop on top of it. Work on it. Do something yourself.
One more hint: your curve looks more like a irregular trochoid wave than a sinusoid wave.
Your curve seems to be best achieved by joining arcs, but if you want to use formulasā¦
You can improve the curvature by applying a X offset function coherent with the sine wave shape (replacing the top GraphMapper with something smarter).
wave.gh (15.1 KB)
2 Likes
Thereās really too little information provided. What are we supposed to do, start fourier analysis? 
Im sorry I thought a forum is for people asking for advice and help on how to solve a problemā¦ if you think you are too intelligent and better than everyone else then donāt reply at all. Get off your high horse.
This is your answer again.
You have to provide more information about the curve. You have to show interest solving the issue not just asking for the solution. This is not McNeel technical support. I am willing to help but I will not do the job for you!
Youāre not asking for advice, youāre asking for the solution. Btw advices have been given!
Update:
- What is this curveās purpose?
- What is this curve derived from?
- How sensitive the final solution should be regarding deviations from this curve?
- Is it a MUST that the curve is created from arcs (similar to @Dani_Abaldeās suggestion)?
- What do you know about this curve? Do you have a set of points this curve must go through?
Now that these questions are layed down. Would you be able to answer your question if you were on my place? (āon the high horseā)
Iāll also stay on the high horse, thanks.
Hereās some reading material.
https://discourse.mcneel.com/t/how-to-ask-effective-questions/50034/2
Curves in Rhino/Grasshopper require more than an equation. You can use an equation like t+\frac{\sqrt{1-x^{2}}}{g} to generate specific points on this ideal curve, but to actually create a curve object requires you sample the equation at various parameters and then connect these sampled dots. Either with a polyline, or a smooth curve, or an interpolated curve.
Either way your resulting curve will be an approximation of your ideal curve. To create an analytically exact shape you will have to generate the elliptical or circular arcs yourself.
thank you, your way of thinking is right but what I want to do to get the curve is to find a strategy to position the exact points in that space. Before I had found these points with rhino, studying the geometry of the spline. Now I am looking to divide the problem into small parts. One of these problems is obtaining three maximum points of the curve, how it is shown in the image (the red part).
t+ā1āx^2/g
I thought of checking these three points with
where t parameter regulates the height of the z axis and the g parameter reduces the radius of the curve. Do you think this is the right strategy? I tried to do this with grasshopper but nothing happens because surely I made a mistake.
2 posts were split to a new topic: Per-object rotation
Hi, what if I want to apply this long sine wave to a circle? Does anyone know how to do it? Thanks you very much
sine_around_circle_2024Apr28a.gh (10.4 KB)
P.S. Laterā¦ version ābā:
sine_around_circle_2024Apr28b.gh (11.1 KB)
Does the generated curvature have to absolutely match that of sine curves?
Iāve made a bunch of very similar looking Interpolated curves based solely on points at the peaks and valleys of the sine curves. These points are simple to make from divided circles.
There appear to be āharmonicsā(?) between āCyclesā and āCountā (resolution) values.
Perhaps off-by-one errors?
sine_around_circle_2024Apr28d.gh (17.3 KB)
Good case for creating a cluster for duplicate componentsā¦
Hello everyone, I apologize, Iāve been trying to solve this problem, but I havenāt been able to. As you can see in the image, I have a surface with a flat, irregular, closed curve with three holes at different heights. If you look closely, thereās a lower, external curve, which is also irregular, but the only difference is that itās spatial (the points of this curve are not contained in a plane, they only respect the same points in their (x,y) coordinates). The question is: how can I make the mesh adapt to this lower, irregular, spatial curve while maintaining everything else? I look forward to your help. Best regards.
Hi @Eberthson I find the formatting of your post makes it hard to read. Personally I would paste plain text unless you have a good reason for something else.
And the picture isnāt thereā¦