/**
a sphere that dissolves into a spiral by <a href="http://www.local-guru.net/blog">guru</a>
*/

float R = 100;
float num = 4;
float f = 0.5;

void setup() {
  size(300,300,P3D);
  frameRate(25);
}

float rot = 0;

void draw() {
  
  float f = map( mouseX, 0, width, 0.9, 0.1);
  
  background(0);
  noStroke();
  fill(0,255,0);
  lights();
  translate( width/2, height/2);
  rot += 0.1;
  rotateY( rot );

  beginShape( QUAD_STRIP);

  for( float a = -360 * num; a<360 * num; a++) {
    
    float h = R * a / ( 360 * num ); 
    float r = sqrt( R*R - h*h);
      
     float x = cos( radians(a))*r;
     float y = sin( radians(a))*r;


    float a2 = a + 360;
    float h2 = R * (a2) / ( 360 * num ) - f * 100 / num; 
    float r2 = sqrt( R*R - h2*h2);
      
     float x2 = cos( radians(a2))*r2;
     float y2 = sin( radians(a2))*r2;

     
     vertex( x,  h,  y  );
     vertex( x2, h2, y2 );
     
  }
  endShape();

}