moving the OpenGL examples to the core

java/examples/OpenGL/Advanced/Particles/Particle.pde

@@ -0,0 +1,58 @@
+class Particle {
+
+  PVector velocity;
+  float lifespan = 255;
+  
+  PShape part;
+  float partSize;
+  
+  PVector gravity = new PVector(0,0.1);
+
+
+  Particle() {
+    partSize = random(10,60);
+    part = createShape(QUAD);
+    part.noStroke();
+    part.texture(sprite);
+    part.normal(0, 0, 1);
+    part.vertex(-partSize/2, -partSize/2, 0, 0);
+    part.vertex(+partSize/2, -partSize/2, sprite.width, 0);
+    part.vertex(+partSize/2, +partSize/2, sprite.width, sprite.height);
+    part.vertex(-partSize/2, +partSize/2, 0, sprite.height);
+    part.end();
+    
+    rebirth(width/2,height/2);
+    lifespan = random(255);
+  }
+
+  PShape getShape() {
+    return part;
+  }
+  
+  void rebirth(float x, float y) {
+    float a = random(TWO_PI);
+    float speed = random(0.5,4);
+    velocity = new PVector(cos(a), sin(a));
+    velocity.mult(speed);
+    lifespan = 255;   
+    part.resetMatrix();
+    part.translate(x, y); 
+  }
+  
+  boolean isDead() {
+    if (lifespan < 0) {
+     return true;
+    } else {
+     return false;
+    } 
+  }
+  
+
+  public void update() {
+    lifespan = lifespan - 1;
+    velocity.add(gravity);
+    
+    part.tint(255,lifespan);
+    part.translate(velocity.x, velocity.y);
+  }
+}

java/examples/OpenGL/Advanced/Particles/ParticleSystem.pde

@@ -0,0 +1,36 @@
+class ParticleSystem {
+  ArrayList<Particle> particles;
+
+  PShape particleShape;
+
+  ParticleSystem(int n) {
+    particles = new ArrayList<Particle>();
+    particleShape = createShape(PShape.GROUP);
+
+    for (int i = 0; i < n; i++) {
+      Particle p = new Particle();
+      particles.add(p);
+      particleShape.addChild(p.getShape());
+    }
+  }
+
+  void update() {
+    for (Particle p : particles) {
+      p.update();
+    }
+  }
+
+  void setEmitter(float x, float y) {
+    for (Particle p : particles) {
+      if (p.isDead()) {
+        p.rebirth(x, y);
+      }
+    }
+  }
+
+  void display() {
+
+    shape(particleShape);
+  }
+}
+

java/examples/OpenGL/Advanced/Particles/Particles.pde

@@ -0,0 +1,31 @@
+// Particles, by Daniel Shiffman
+
+ParticleSystem ps;
+PImage sprite;  
+
+void setup() {
+  size(640, 400, P3D);
+  orientation(LANDSCAPE);
+  sprite = loadImage("sprite.png");
+  ps = new ParticleSystem(10000);
+
+  // Writing to the depth buffer is disabled to avoid rendering
+  // artifacts due to the fact that the particles are semi-transparent
+  // but not z-sorted.
+  hint(DISABLE_DEPTH_MASK);
+} 
+
+void draw () {
+  background(0);
+  ps.update();
+  ps.display();
+  
+  ps.setEmitter(mouseX,mouseY);
+  
+  fill(255);
+  textSize(16);
+  text("Frame rate: " + int(frameRate),10,20);
+  
+}
+
+