Smoothing s=new Smoothing();
PFont f;

void setup(){
  size(400,400);
  smooth(); 
  f=loadFont("font.vlw");
  textFont(f,32);
  textAlign(RIGHT);
}

int type=11;

void draw(){
  background(255);

  drawFunction(type);
  fill(0);
  text(s.nameForFn(type),width-20,height-20);
}

void mousePressed(){
  type++;
  if(type>=s.count) type=0;
}

void drawFunction(int which){
  //draw background
  noStroke();
  fill(255-which*5);
  rect(0,0,height,height);
  
  //flip axes
  pushMatrix();
  scale(1,-1);
  translate(0,-height);
  
  //draw curve
  stroke(0);
  for(float i=1;i<width;i++){
    line(i-1,s.fn(which,i-1,height),i,s.fn(which,i,height)); 
  }
  
  //revert axes
  popMatrix();
}