# Sine function on a closed brep

There are plenty of tutorials on how to create a 3d sine wave using sine cos functions on a flat surface…

I’ve been struggling to do the same on a cylinder and a sphere similar to the image below… I tried playing w polar coordinates in different ways… the results are so useless not even worth posting … I only managed to make it in z direction on a cylinder … But not on the other rounded direction…

Any tips is appreciated

dear @Gin_Ko
just a starting-point:
i belief that most of this stuff is done by lofting horizontal or (this) example radial curves.
The sin function might help to offset the control points.
(sin Function is based on Rad 360 Degree = 2 Pi)

crvs_for_vase.3dm (303.4 KB)

did you search for grasshopper parametric vase tutorials ?

hope this helps - kind regards -tom

Dear @Tom_P

Thx 4 the reply… I understand making this w loft would be quite easy… In fact this is not what I’m trying to make… Its a starting point, i plan to mess w the sine function after making that and incorporate different noises in it…

I’m more curious about the math problem behind my question… I just grabbed the first picture i could to show the kind of effect im after…

This is a 2 Dimensional Sine Equation (or something like that)

z= Sin(x) * Sin(y)

In the image you shared, it is more like a grid mapped into a cylinder
2D Sine.gh (10.3 KB)

for the cylindrical option, you can divide the surface and apply the sine function to Z coordinates and the Other one to the Polar Coordinates, In this case I used the location of the point within the data tree instead of the polar coordinates just for simplicity.

2D Sine.gh (24.3 KB)

Dear @tay.alrawi

I had tried using both index number and xy rotation from polar coordinates as the input to the sine function… and both worked…

turns out my issue was thinking about a sphere and a cylinder at the same time and using the origin instead of each branch’s average point as the starting point of my vectors…

I added the sphere version too… for that just needed to replace the average point with (0,0,0) and few more tweaks… it looks a bit distorted though but can make it look better by having less number of waves in the z direction…

2D Sine-ed1.gh (31.8 KB)

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Looks good, what I like about NURBS generally it is just a UV surface whether it is a plane, sphere or cylinder.