1- First we have to write in command grasshopper, then we have that we will have to go to file and select new document. Then in rhino click in perspective to see it better.
2- We will have to put in one middle of the screen rhino and the other part grasshopper.
3- The next step is to draw a circle, we will have to go to curve, then in primitive we need to select the command circle and then drop it were you want. Then we go to change the plane and then to vector, click on the command YZ plane, then drop it wherever you want..
4- Then you have to connect the small semicircle of YZ to the P that is on cir.
5- then you have to go to params go to input and select the command number slider and again you can drop it wherever you want. Go over slider with the right bottom and then click edit, suddenly it will appear a page that you will have to change the digits from 3 to 0. Then you will have to click on max and write 20. Finally you will have to click OK.
6- Then we will have to connect radius with cir (R)
7- next press curve, then you have to click on division and press the command perpendicular frames and drop it.
8- First we have to select radius, then we have to press control and v and repeat this but with finally you have to connect count with PFrames (N) and we have to put it in 16.
10-The next thing you have to do is go to vector point and select construct a point. Then you have to copy the radius by pressing first control c and then control v. Then you have to connect x coordinates with the x of pt.
11- Go to maths then click on operators and chose negative and then you have to put it between value and first pt. When you have finished that you have to click on curve, spiline and then press on curve on surface.
12- Then you have to connect Pframes with CrvSrf. Then you have to connect pt with CrvSrf and press shift and then connect the other y of pt to CrvSrf uv and then pt with c of CrvSrf and finally the other pt with c of CrvSrf.
13- Connect neg with Y of pt and value with Y of pt and then disconnect X of pt to value.
14- Then go to params , select primitive and click on the command integer . Click on it with the right bottom of your mouse then select setinteger then click on 180 and then to Copy on slider.
15- To multiply 180 you have to go to maths and click over operators and select multiplication . Then you have to connect 180 with A of A B and the A to A B. Then you have to put Bin in 1.
16- For creating a range you have to go to sets select sequence and click on range also you have to connect A B to Range. The next thing is to connect Count with Range.
17- Go to transform then to euclidean and click on the firs rotate that appears. Y ou have to connect C of CrvSrf with G of Rotate, the R of Range with A of Rotate, press control and connect F of PFrames with P of Rotate.
18- Then go to Maths select trig and click on Radians. Drop it between Rages and Rotate. Then press control and go back words with the connection of R of Range and A of Rotate and connect R of Range to D of Rad and R of Rad to A of Rotate.
19- Go to surface select Freeform and click on top of Loft . Then connect G of Rotate with C of loft. Then go to the blue bottom and press on it, then select high cuality.
20-To put it in Rhino you have to go to solutions and click on Bake Selected.
FINALY YOU WOULD HAVE SOMETHING LIKE THIS