int numVecX = 40;
int numVecY = 40;
Thing[] things;
color[] colors;
int frame;

void setup() {
  size(400,400, P3D);
  PImage img = loadImage("col.png");
  img.loadPixels();
  colors = img.pixels;
  frame = 0;
  background(255,255,255);
  things = new Thing[numVecX*numVecY];
  for (int y=0; y<numVecY; y++) {
    for (int x=0; x<numVecX; x++) {
      things[y*numVecX+x] = new Thing((width*x)/numVecX, (height*y)/numVecY);
    }
  }
  for (int y=1; y<numVecY-1; y++) {
    for (int x=1; x<numVecX-1; x++) {
      things[y*numVecX+x].neighbors[0] = things[(y-1)*numVecX+x-1];
      things[y*numVecX+x].neighbors[1] = things[(y-1)*numVecX+x];
      things[y*numVecX+x].neighbors[2] = things[(y-1)*numVecX+x+1];
      things[y*numVecX+x].neighbors[3] = things[(y)*numVecX+x-1];
      things[y*numVecX+x].neighbors[4] = things[(y)*numVecX+x+1];
      things[y*numVecX+x].neighbors[5] = things[(y+1)*numVecX+x-1];
      things[y*numVecX+x].neighbors[6] = things[(y+1)*numVecX+x];
      things[y*numVecX+x].neighbors[7] = things[(y+1)*numVecX+x+1];
    }
  }
    
}

void draw() {
  frame++;
  
  if (frame%20 == 0) {
    fill(255,255,255,1);
    rect(0,0,width,height);
  }
//  framerate(12);
  int numThings = numVecX*numVecY;
  for (int i=0; i<numThings; i++) {
    things[i].process();
  }
//  background(255,255,255);
  for (int i=0; i<numThings; i++) {
    things[i].update();
  }
  
}


class Thing {
  int posX, posY;
  vec v, newV;
  Thing[] neighbors;
  float rot = 0;
    float lim = 40;
  float energy;

  public Thing(int x, int y) {
    posX = x;
    posY = y;
    neighbors = new Thing[8];
    init();
  }
  
  public void init() {
    energy = 0;
    v = new vec(random(-1,1),random(-1,1));
    rot = random(-20, 20);
    v.div(v.mag());
    newV = new vec(v.x,v.y);
  }
  
  void process() {
    float avg = 0;
    if (neighbors[0] != null) {
      for (int i=0; i<8; i++) {
        avg+=neighbors[i].rot;
      }
      avg /= 8;
      rot = rot+avg/3;
    }
    rot *= 0.735;

    vec mVec = new vec((float) (mouseX-pmouseX), (float) (mouseY-pmouseY));
    float m = mVec.mag();
    if (m != 0 && pmouseX>=0 && pmouseX<width && pmouseY>=0 && pmouseY<height) {
      mVec.div(m);
      float midX = (float)(pmouseX+mVec.x/2);
      float midY = (float)(pmouseY+mVec.y/2);
      vec tmVec = new vec((float)(midX-posX), (float)(midY-posY));
      float d = tmVec.mag();
      if (d<m/2+5) { // influence
        float ang = -newV.ang()+mVec.ang();
        rot = ang*0.9+rot*0.1;
        energy += (int) ((abs(rot)/lim)*(colors.length-1));
      }
    }
    float deg = rot / 360f * TWO_PI;
    newV.x = v.x*cos(deg)-v.y*sin(deg);
    newV.y = v.x*sin(deg)+v.y*cos(deg);
      if (rot>lim) rot = lim;
      if (rot<-lim) rot = -lim;
  }
  
  void update() {
    v.x = newV.x;
    v.y = newV.y;
    float s = abs(rot);
    if (s>lim) s=lim;
    int c = (int) (255-(s/lim)*255);
    fill(255,c,c,10);
    s = (s/lim)*40+3;
    
    if (mousePressed) {
    ellipseMode(CENTER);
    noStroke();
    ellipse(posX,posY,s, s);
    }
    c = 64+(int) ((abs(rot)/lim)*191);
//    stroke(c,c,c,(int) ((abs(rot)/lim)*40)+40);
    if (energy >= colors.length) energy = colors.length-1;
    energy *= 0.995;

    int col = colors[(int) (energy)];
    stroke( red(col), green(col), blue(col), ((int) ((abs(rot)/lim)*40)+40) );
    
    s = ((abs(rot)/lim)*65+5);
    line(posX, posY, posX+(int) (v.x*s), posY+(int) (v.y*s));
  }
  

}

void keyReleased() {
  if (key==' ') {
    background(255,255,255);
    for (int i=0; i<numVecX*numVecY; i++) {
      things[i].init();
    }
  }
}