Code: straight_line_torus by mtchl

// a straight line (on a toroidal surface) 
// mitchell whitelaw - http://teemingvoid.blogspot.com
// for instructionset.org
// 20 may 2008

int offset = 0;
int line_length = 0;
int line_length_max = 5000;

int inner_radius = 120;
int outer_radius = 40;

float inner_rotation_min = 0.001;
float inner_rotation_max = 0.02;
float outer_rotation_min = 0.001;
float outer_rotation_max = 0.05;

float inner_rotation = random(inner_rotation_min,inner_rotation_max);
float outer_rotation = random(outer_rotation_min,outer_rotation_max);

void setup(){
  size(600,400,P3D);
}

void draw(){ 
  background(0);
  translate(width/2,height/2);
  rotateX(mouseY*-0.01);
  rotateZ(mouseX*0.01);
  stroke(255,150);
  for (int v=0; v<line_length; v++){
    pushMatrix();
    rotateY((v+offset)*inner_rotation);
    translate(inner_radius,0);
    rotateZ((v+offset)*outer_rotation);
    translate(0,outer_radius);
    point(0,0);
    popMatrix();
  }
  if (line_length > line_length_max) {
    offset+=10;
  } else {
    line_length+=10;
  }
}

void mousePressed(){
 inner_rotation = random(inner_rotation_min,inner_rotation_max);
 outer_rotation = random(outer_rotation_min,outer_rotation_max);
 offset = 0;
 line_length = 0;
}