int amplitude=10, frequency=TWO_PI/60, phase=0, k=1, leng=120;
int v[]=new int [leng];
int r[]=new int [leng];
final int LOOPED=0, FIXED=1, FREE=2, MIXED=3;
int ends=LOOPED;    
boolean circular=true;
color colour;
color colours[]=new color[leng];
//int sinArray[]=new int[721];

int xPos, yPos, oldxPos, oldyPos, c, i, t;
int tinc = TWO_PI/150;
int finc = TWO_PI/1000;
int drawStyle=1, mode=2;
int dp=leng*3/4; // driver position

void simulateStep(){
    // Forces between neighbours:
    for (i=1;i<leng-1;i++){
        v[i]+=k*(r[i-1]+r[i+1]-2*r[i])/10;
    }
    
    if (ends==LOOPED){
        v[0]+=k*(r[leng-1]+r[1]-2*r[0])/10;
        v[leng-1]+=k*(r[leng-2]+r[0]-2*r[leng-1])/10;       
    }
    else if (ends==FIXED){
        v[0]+=k*(0-r[0])/10;
        v[leng-1]+=k*(0-r[leng-1])/10;
    }
    else if (ends==FREE){
        v[0]+=k*(r[1]-r[0])/10;
        v[leng-1]+=k*(r[leng-2]-r[leng-1])/10; 
    }
    else if (ends==MIXED){
        v[0]+=k*(0-r[0])/10;
        v[leng-1]+=k*(r[leng-2]-r[leng-1])/10; 
    }                

   for (i=0;i<leng;i++){
    	r[i]+=v[i];
    }

    r[dp]+=amplitude*sin(phase);
    phase+=frequency;

 }

public void reset(){
        for (i=0; i<leng; i++){
           r[i]=0;
           v[i]=0;          
        }
        phase=0;
}

void draw(){

  //if(t<-10.0 && t>-10.2) println ("fps: " t*10000/millis());
  t=0;
  background(0);
  simulateStep();
  if (circular) {
    oldxPos= width/2+ fptoi(fptoi((itofp(height)/4+r[(leng-1)])*cos((leng-1)*TWO_PI/leng)));
    oldyPos=height/2+ fptoi(fptoi((itofp(height)/4+r[(leng-1)])*sin((leng-1)*TWO_PI/leng)));
  } 
  else {
    oldxPos=0;
    oldyPos=height/2;
  }
  if (drawStyle==2) {
    beginShape(POLYGON);
    if (!circular) {
      vertex(width, height);
      vertex(0,height);
    }
  }
  for (int i=0; i<leng; i++) {
    if (circular) {
      xPos= width/2+ fptoi(fptoi((itofp(height)/4+r[i])*cos(i*TWO_PI/leng)));
      yPos=height/2+ fptoi(fptoi((itofp(height)/4+r[i])*sin(i*TWO_PI/leng)));

    }
    else {
      xPos=(i*width)/leng;
      yPos=fptoi(r[i])+height/2;
    }
    stroke (colours[i&255]);
    if (drawStyle==1) line(xPos, yPos, oldxPos, oldyPos);
    else if (drawStyle==0) point(xPos, yPos);
    else if (drawStyle==2) vertex(xPos, yPos);
    oldxPos=xPos;
    oldyPos=yPos;
    i++;
    }
    if (drawStyle==2) endShape();

  if (keyPressed){
    if (keyCode==UP) amplitude++;
    if (keyCode==RIGHT) frequency++;    
    if (keyCode==DOWN) amplitude--;
    if (keyCode==LEFT) frequency--;    
  }
}

void dot (int xPos, int yPos) {
    point(xPos,yPos);
}

void setup() { 
  framerate(60); 
  i=0;
  /*while (i<720){
    sinArray[i]=sin(PI/360)*100;
    i++;
  }*/
  setColours(mode);
  fill(0,leng,leng);
  reset();
  draw();
} 

void setColours(int mode){

  if (mode==0){
    colorMode(HSB,leng);
    i=0;
    while (i<leng){
      colours[i]=color(i,0,leng);
      i++;
    }   
  }
  if (mode==1){
    colorMode(HSB,leng);
    i=0;
    while (i<leng){
      colours[i]=color(i,leng/2,leng);
      i++;
    }   
  }
  if (mode==2){
    colorMode(HSB,leng);
    i=0;
    while (i<leng){
      colours[i]=color(i,leng,leng);
      i++;
    }   
  }    
}

void keyPressed(){
    if (key=='0') drawStyle=(drawStyle+1)%2;
    if (key=='1') circular=!circular;
    if (key=='2') ends=(ends+1)%3;
    if (key=='9') setColours((mode++)%3);   
    if (keyCode==FIRE) reset();
}