if(x < 0) x = width - 1;
if(x > width - 1) x = 0;
if(y < 0) y = height- 1;
if(y > height- 1) y = 0;
 

import processing.opengl.*;

int anzahl=10000;
float[][] P = new float[anzahl][2];

float pns=0.005; //Perlin noise size
float ps=10; //Patternsize Vectorfield
float w;//Winkel
float vx,vy;
float x=100,y=100,z;
float v0=1; //Geschwindigkeit


void setup(){
  size(800,800,OPENGL);
  background(0);
  pointrand();
}

void draw(){

  fill(0,100);
  rect(0,0,width,height);
  z+=5;
  if (mousePressed && (mouseButton == RIGHT)) {
    pointrand();
  }
  if (mousePressed && (mouseButton == LEFT)) {
    feld();
  }
  for (int i=0;i<anzahl;i++){
    x=P[i][0];
    y=P[i][1];
    w=noise(x*pns,y*pns,z*pns)*TWO_PI;
    vx=sin(w);
    vy=cos(w);
    x+=vx*v0;
    y+=vy*v0;

    if(x < 0) x = width - 1;
    if(x > width - 1) x = 0;
    if(y < 0) y = height- 1;
    if(y > height- 1) y = 0;  

    P[i][0]=x;
    P[i][1]=y;
    stroke(w/TWO_PI*255,255-w/TWO_PI*255,0,100);
    line(x,y,x+vx*5,y+vy*5);
  }
}

void feld(){
  for(int x1=0;x1<width;x1+=ps){
    for(int y1=0;y1<width;y1+=ps){
	w=noise(x1*pns,y1*pns,z*pns)*TWO_PI;
	stroke(w/TWO_PI*255,150);
	line(x1,y1,x1+ps*sin(w),y1+ps*cos(w));
    }
  }
}

void pointrand(){
  for (int i=0;i<anzahl;i++){
    P[i][0]=random(0,width);
    P[i][1]=random(0,height);
  }
}