/** a 3D rotating moebius-Strip my 
<a href="http://www.local-guru.net/blog">guru</a>
*/

void setup() {
  size(300,300,P3D);
}

float a = 0;


void draw() {
  background(0);
  lights();
  noStroke();
  fill(128,255,0);
  float r = 100;
  translate( width/2, height/2 );
  a += 0.01;
  rotateY( a );
  rotateX( a );
  beginShape( QUAD_STRIP );
  for ( int i =0; i < 37; i++) {
    float x = cos( radians( i * 5.0)) * 30;   
    float z = sin( radians( i * 5.0)) * 30;

    float xa = ( r + x ) * cos( radians( i * 10.0 ));
    float ya = ( r + x ) * sin( radians( i * 10.0 ));

    float xb = ( r - x ) * cos( radians( i * 10.0 ));
    float yb = ( r - x ) * sin( radians( i * 10.0 ));

    vertex( xa, ya, z );
    vertex( xb, yb,-z );
  }
  endShape(CLOSE);
}