###### Descriptions and Examples for the POV-Ray Raytracerby Friedrich A. Lohmüller About Loops with POV-Ray
Italiano
Français
Deutsch

Home
- POV-Ray Tutorial

Loops in POV-Ray
1. For + While
Comparison
2. Linear
Transformations
3. Circular
Transformations
>4. Moebius etc.
5. Screws
& Spirals
6. Twisting
Spirals
7. Snails
& Ammonites
8. Spherical Spirals 1
9. Spherical Spirals 2
10. Fibonacci Spirals

## Loops and Moebius and Similar Things

If we use for double rotation a stick instead of a sphere as the basic element and reduce the number of inner rotations to 0.5 we get as so called Moebius strip - this kind of tape has only on side:

 ```//------------------------------------ #declare P_R =0.1; #declare P_H =0.75; #declare Profile = union{ sphere {<0, P_H,0>,P_R } cylinder{<0,-P_H,0>,<0,P_H,0>,P_R} sphere {<0,-P_H,0>,P_R } texture{ pigment{color rgb<0.65,0.35,0.85>} finish {phong 1}} } //---------------------------------- #declare Radius_major = 3.00; #declare N_major = 0.5; #declare N_minor = 2500; //------------------------------------ #declare Nr=0; // start #declare EndNr=N_major*N_minor;// end #while (Nr< EndNr) object{Profile rotate<0,0,Nr*360/N_minor> translate rotate<0,Nr*360/EndNr,0>} #declare Nr = Nr + 1; //next Nr_minor #end // --------------- end of loop --```
Scene file for POV-Ray: povloopm.pov
or: povloopm.txt

If we change the number
of the inner rotations to 2.5,
we will see the following:

 ```//---------------------------------- #declare N_major = 2.5; //----------------------------------```

In the case of integer numbers of inner rotations we are getting tapes with 2 surfaces, in the case of 0.5 , 1.5, 2.5 etc. inner rotations we will get a tape with only one side.

Scene file for POV-Ray: povloopn.pov
or: povloopn.txt

 ```//--------------------------------- #declare P_R = 0.2; #declare P_H = 0.65; #declare Profile = union{ sphere {<0, P_H,0>,P_R } cylinder{<0,-P_H,0>,<0,P_H,0>,P_R} cylinder{<0,-P_H,0>,<0,P_H,0>,P_R translate<0.01,0,0> texture{pigment{color rgb<1,.65,0>} finish {phong 1}}} sphere {<0,-P_H,0>,P_R } texture{pigment{color rgb<1,0.3,0.7>} finish {phong 1}}} //--------------------------------- #declare N_major = 4; //---------------------------------```
Scene file for POV-Ray: povloopo.pov
or: povloopo.txt

 Overview | For + While | Linear | Circular | Moebius | Screws+Spirals | Twisted Spirals | Snails | Spherical 1 | Spherical 2 | Fibonacci |
top

 © Friedrich A. Lohmüller, 2014 http://www.f-lohmueller.de