// Dartmouth CS 2, Winter 2009, Chris Bailey-Kellogg
// Notes 13 | Sketch 5
// Based on Processing example Topics | Simulate | SmokeParticleSystem

int num = 100;  // total number of particles
int curr = 1;   // how many are active
Particle[] particles = new Particle[num];
Random generator = new Random();

float wind = 0; // additional x increment

void setup()
{
  size(200,200);
  smooth();
  background(0);
  frameRate(30);
 
  // From the referenced Processing example
  // Create an alpha masked image to be applied as the particle's texture
  PImage msk = loadImage("texture.gif");
  PImage img = new PImage(msk.width,msk.height);
  for (int i = 0; i < img.pixels.length; i++) img.pixels[i] = color(255);
  img.mask(msk);
  
  // Create the particles
  for (int i=0; i<num; i++)
    particles[i] = new Particle(width/2, height, img); 
}

void draw()
{
  background(0);

  // Compute the amount of wind, between -1 and 1
  wind = 2.0*mouseX/width - 1.0;
  // Draw an arrow in the direction of the wind,
  // with length between -50 and 50
  stroke(255);
  pushMatrix();
  translate(width/2,10);
  if (wind<0) rotate(PI);
  float len = 50*abs(wind);
  line(0,0,len,0);
  line(len,0,len-4,2);
  line(len,0,len-4,-2);
  popMatrix();

  // Draw and update however many have been allowed to enter
  // (one per frame, till all have entered)
  for (int i=0; i<curr; i++) particles[i].draw();
  for (int i=0; i<curr; i++) particles[i].update(wind);
  if (curr<num) curr++;  // bring in the next
}