yet_another_danmaku_in_processing.pde

/**
 * Yet another DANMAKU #1 rev2
 * ===========================
 * Bullets now reflect @ walls!
 * 
 * This sample assigns bullet objects every time when new bullets are
 * needed. Creating a new bullet costs much, we'd better find an another
 * way to manage bullets.
 */

ArrayList bullets;

float launchDegree = 90;
float launchDegreeDelta = 3.6;

float OUT_OF_BOUND_MERGIN = 50.0;

///////////////////////////////////////////////////////////

void setup() {
  size(400, 400);
  smooth();
  frameRate(30);

  bullets = new ArrayList(1024);
}

void draw() {
  background(238);
  {
    Bullet bullet = null;
    {
      bullet = new Bullet(width/2, 20);
      bullet.setSpeed(4.0, launchDegree);
      bullets.add(bullet);
    }
    {
      bullet = new Bullet(width/2, 20);
      bullet.setSpeed(3.6, launchDegree+3);
      bullets.add(bullet);
    }
    {
      bullet = new Bullet(width/2, 20);
      bullet.setSpeed(3.6, launchDegree-3);
      bullets.add(bullet);
    }
    if (launchDegree > 175 || launchDegree < 5) {
      launchDegreeDelta *= -1;
    }
    launchDegree += launchDegreeDelta;
  }

  for(Iterator it = bullets.iterator(); it.hasNext();) {
    Bullet bullet = (Bullet) it.next();
    bullet.move();
    if (bullet.isOutOfBound()) {
      it.remove();
    } 
    else {
      bullet.draw();
    }
  }
} 

/**
 * Bullet Class
 */
class Bullet {
  float x;
  float y;
  float vx;
  float vy;
  float size = 5;
  int reflectionCount = 1;

  public Bullet(float x, float y) {
    this.x = x;
    this.y = y;
  }
  void setSpeed(float v, float degree) {
    vx = v * cos(radians(degree));
    vy = v * sin(radians(degree));
  }
  void setSpeedWithRadian(float v, float radian) {
    vx = v * cos(radian);
    vy = v * sin(radian);
  }
  void draw() {
    if (this.reflectionCount > 0) {
      stroke(0);
    } else {
      stroke(0xFFb00000);
    }
    ellipseMode(CENTER);
    ellipse(x, y, size, size);
  }
  void move() {
    this.x += vx;
    this.y += vy;

    // Reflection at top, right, and left walls
    if (this.x < size ||
      this.x > width - size ||
      this.y < size) {
      if (this.reflectionCount > 0) {
        float targetRadian = atan2(mouseY - this.y, mouseX - this.x);
        this.setSpeedWithRadian(3.6, targetRadian);
        this.reflectionCount--;
      }
    }
  }
  boolean isOutOfBound() {
    return (this.x < - OUT_OF_BOUND_MERGIN ||
      this.x > width + OUT_OF_BOUND_MERGIN ||
      this.y < - OUT_OF_BOUND_MERGIN ||
      this.y > height + OUT_OF_BOUND_MERGIN
      );
  }
}