// Flux 00 (2005. 1. 8.)
// by SeungJoon Choi
// erucipe@hanmail.net
// 
// http://processing.org

VCell[] vcells;
Particle[] ptcls;
int nw, nh, n_ptcls;
float csize;
//float[] clearZ;

int kR, kG, kB;

void setup()
{
  size(400, 300);
  background(255);
  rectMode(CENTER_DIAMETER);
  //clearZ = new float[width*height];
  //System.arraycopy(clearZ, 0, g.zbuffer, 0, g.zbuffer.length);
  g.depthTest = false;
  noStroke();
  
  nw = 8;
  nh = 6;
  csize = width / nw;
  vcells = new VCell[nw * nh];
  for(int y = 0; y < nh; y++)
  for(int x = 0; x < nw; x++)
  {
    int i = y * nw + x;
    vcells[i] = new VCell(x * csize - (nw - 1) * csize * 0.5,
                          y * csize - (nh - 1) * csize * 0.5,
                          csize);    
  }
  
  kR = (int)random(255);
  kG = (int)random(255);
  kB = (int)random(255);
  color pcolor = color(kR, kG, kB);
  
  n_ptcls = 100;
  ptcls = new Particle[n_ptcls];
  for(int i = 0; i < n_ptcls; i++)
  {
    ptcls[i] = new Particle((1-random(2))*200, (1-random(2))*150, 0, pcolor);
  }  
}

void loop()
{
  if(random(1) > 0.8)
  {
    fill(255, 255, 255, 1);
    rect(width*0.5, height*0.5, width, height);
  }
  push();
  beginCamera();
  perspective(60, (float)width / (float)height, 1, 1000);
  //lookat(0, 0, 261, 0, 0, 0, 0, 1, 0);
  lookat(0, 0, 261 - 10*(1+sin(millis()*0.001)), 0, 0, 0, 0, 1, 0);
  endCamera();
  pop();
  
  if(mousePressed)
  {
    background(255);
    stroke(kR, kG, kB);
    drawVCells(); 
  }
  
   drawPtcls();
   push();
   //translate(0, 0, 1);
   rotateY(PI*0.01 * cos(millis()*0.01));
   drawPtcls();
   pop();
}

void mouseReleased() 
{
  //System.arraycopy(clearZ, 0, g.zbuffer, 0, g.zbuffer.length);
  background(255);
  kR = (int)random(255); 
  kG = (int)random(255);
  kB = (int)random(255);
  for(int i = 0; i < n_ptcls; i++)
  {
    ptcls[i].kr = kR + (int)((1-random(2))*64);
    ptcls[i].kg = kG + (int)((1-random(2))*64);
    ptcls[i].kb = kB + (int)((1-random(2))*64);
  }  
} 

void drawVCells()
{
  for(int y = 0; y < nh; y++)
  for(int x = 0; x < nw; x++)
  {
    int i = y * nw + x;
    vcells[i].Draw();
  }
}

void drawPtcls()
{
  for(int i = 0; i < n_ptcls; i++)
  {
    ptcls[i].Move();
    ptcls[i].Draw();
  }
}

class VCell
{
  public VCell(float _x, float _y, float _size)
  {
    x = _x;
    y = _y;
    size = _size;
    arrow = new Arrow(x, y, size, (1-random(2))*PI);
  }
  
  public void Draw()
  {
    push();
    translate(x, y, 0);
    rect(0, 0, size, size);
    if(mousePressed) takeAngle();
    arrow.Draw();
    pop();
  }
  
  private void takeAngle()
  {  
    if(mouseY > screenY(0, -size*0.5, 0) && mouseY < screenY(0, size*0.5, 0))
    if(mouseX > screenX(-size*0.5, 0, 0) && mouseX < screenX(size*0.5, 0, 0))
    {
      arrow.angle = atan2(mouseY - pmouseY, mouseX - pmouseX);
      //arrow.angle = atan2(mouseY - screenY(0, 0, 0), mouseX - screenX(0, 0, 0)) + PI*0.5;
    }
  }
  
  public float x, y, size;
  Arrow arrow;
}

class Arrow
{
  public Arrow(float _ox, float _oy, float _size, float _angle)
  {
    ox = _ox;
    oy = _oy;
    radius = _size * 0.5 * 0.75;
    angle = _angle;
  }
  
  public void Draw()
  {
    push();
    rotateZ(angle + PI*0.5);
    beginShape(POLYGON);
    vertex(0, -radius, 0);
    vertex(-radius*0.3, -radius + radius*0.4, 0);
    vertex(-radius*0.1, -radius + radius*0.4, 0);
    vertex(-radius*0.1, radius, 0);
    vertex(radius*0.1, radius, 0);
    vertex(radius*0.1, -radius + radius*0.4, 0);
    vertex(radius*0.3, -radius + radius*0.4, 0);
    vertex(0, -radius, 0);
    endShape();
    //line(0, -radius, 0, radius);
    pop();
  }  
  
  public float ox, oy, radius, angle;
}

class Particle
{
  public Particle(float _x, float _y, float _z, color pcolor)
  {
    oldx = _x;
    oldy = _y;
    oldz = _z;
    x = _x;
    y = _y;
    z = _z;
    
    rw = nw * csize * 0.5;
    rh = nh * csize * 0.5;
    
    ax = 100;
    ay = 100;
    vx = 0;
    vy = 0;
    dt = 0.012;
    
    kr = (int)red(pcolor);
    kg = (int)green(pcolor);
    kb = (int)blue(pcolor);
    
    kr += (int)((1-random(2))*64);
    kg += (int)((1-random(2))*64);
    kb += (int)((1-random(2))*64);
  }
  
  public void Move()
  {
    oldx = x;
    oldy = y;
    oldz = z;
    int ix = (int)((x + rw) / csize);
    int iy = (int)((y + rh) / csize);
    if(ix > nw-1) ix = 0;
    if(iy > nh-1) iy = 0;
    if(ix < 0) ix = nw - 1;
    if(iy < 0) iy = nh - 1;
    
    VCell vcell = vcells[iy * nw + ix];
    vx += ax*cos(vcell.arrow.angle)*dt;
    vy += ay*sin(vcell.arrow.angle)*dt;
    x += vx*dt;    
    y += vy*dt;
    vx *= 0.99;
    vy *= 0.99;
    
    if(x < -rw) {x = rw; oldx = rw;}
    if(x > rw) {x = -rw; oldx = -rw;}
    if(y < -rh) {y = rh; oldy = rh;}
    if(y > rh) {y = -rh; oldy = -rh;}
  }
  
  public void Draw()
  {
    //stroke(kr, kg, kb, 127);
    //line(oldx, oldy, oldz, x, y, z);
    push();
    translate(x, y, 0);
    noStroke();
    fill(kr, kg, kb, 32);
    rect(0, 0, 2, 2);
    pop();
    if(mousePressed)
    {
      push();      
      translate(x, y, 0);
      noFill();
      stroke(kR, kG, kB, 255);
      rect(0, 0, 2, 2);
      pop();  
    }
  }
  
  float oldx, oldy, oldz;
  float x, y, z, rw, rh;
  float vx, vy, ax, ay, dt;
  int kr, kg, kb;
}