Re-adding Topics to SVN

java/examples/Topics/Simulate/SmokeParticleSystem/ParticleSystem.pde

@@ -0,0 +1,57 @@
+// A class to describe a group of Particles
+// An ArrayList is used to manage the list of Particles 
+
+class ParticleSystem {
+
+  ArrayList particles;    // An arraylist for all the particles
+  PVector origin;        // An origin point for where particles are birthed
+  PImage img;
+  
+  ParticleSystem(int num, PVector v, PImage img_) {
+    particles = new ArrayList();              // Initialize the arraylist
+    origin = v.get();                        // Store the origin point
+    img = img_;
+    for (int i = 0; i < num; i++) {
+      particles.add(new Particle(origin, img));    // Add "num" amount of particles to the arraylist
+    }
+  }
+
+  void run() {
+    // Cycle through the ArrayList backwards b/c we are deleting
+    for (int i = particles.size()-1; i >= 0; i--) {
+      Particle p = (Particle) particles.get(i);
+      p.run();
+      if (p.dead()) {
+        particles.remove(i);
+      }
+    }
+  }
+  
+  // Method to add a force vector to all particles currently in the system
+  void add_force(PVector dir) {
+    for (int i = particles.size()-1; i >= 0; i--) {
+      Particle p = (Particle) particles.get(i);
+      p.add_force(dir);
+    }
+  
+  }  
+
+  void addParticle() {
+    particles.add(new Particle(origin,img));
+  }
+
+  void addParticle(Particle p) {
+    particles.add(p);
+  }
+
+  // A method to test if the particle system still has particles
+  boolean dead() {
+    if (particles.isEmpty()) {
+      return true;
+    } else {
+      return false;
+    }
+  }
+
+}
+