From 2e05895a921de45fb869cb252ba85df6f9252d4d Mon Sep 17 00:00:00 2001
From: Timo Hocker <timo@scode.ovh>
Date: Sat, 27 Jun 2020 16:19:15 +0200
Subject: [PATCH] optimization

---
 Boid.java          | 31 +++++++++++++++++++++++--------
 Display.java       |  3 +++
 Main.java          |  6 +++---
 PhysicsObject.java |  2 +-
 4 files changed, 30 insertions(+), 12 deletions(-)

diff --git a/Boid.java b/Boid.java
index b0a4925..040e6f2 100644
--- a/Boid.java
+++ b/Boid.java
@@ -3,12 +3,15 @@ import java.util.ArrayList;
 import java.util.Random;
 
 public class Boid extends PhysicsObject implements Drawable {
-  public Boid(int width, int height) {
+  private int group;
+
+  public Boid(int width, int height, int group) {
     super(0, 0, 0, 0);
     Random r = new Random();
     this.x = r.nextInt(width);
     this.y = r.nextInt(height);
     this.apply_force(r.nextFloat() * 2 - 1, r.nextFloat() * 2 - 1, 1);
+    this.group = group;
   }
 
   @Override
@@ -16,22 +19,34 @@ public class Boid extends PhysicsObject implements Drawable {
     g.fillOval((int) x, (int) y, 2, 2);
   }
 
-  @Override
-  public void simulate() {
+  public void simulate(int group) {
     super.simulate();
-    ArrayList<PhysicsObject> others = ChunkManager.get_objects((int) x, (int) y);
 
-    if (others.size() == 0)
+    // Gruppen werden zeitversetzt aktualisiert um die Performance zu verbessern
+    if (this.group != group)
       return;
 
-    for (PhysicsObject o : others) {
+    ArrayList<PhysicsObject> others = ChunkManager.get_objects((int) x, (int) y);
+
+    int other_count = others.size();
+
+    if (other_count == 0)
+      return;
+
+    for (int i = 0; i < other_count; i++) {
+      // Überprüfung teilweise überspringen, wenn es zu viele objekte in der Nähe gibt
+      if ((i + group) % Math.max(1, other_count / 16) != 1)
+        continue;
+
+      PhysicsObject o = others.get(i);
       double dist = this.get_sqr_distance(o);
       if (dist < 500 && dist > 20) {
-        // Rule 1: collect in groups
+        // Regel 1: Zu anderen hin bewegen
         this.apply_force(o.x - x, o.y - y, (float) Math.min(0.005 / dist, 1));
+        // Regel 3: In die Richtung der anderen fliegen
         this.apply_force(o.v_x, o.v_y, 0.005f);
       } else if (dist < 20) {
-        // Rule 2: keep distance
+        // Regel 2: Abstand halten
         this.apply_force(x - o.x, y - o.y, (float) Math.min(0.005 / dist, 1));
       }
     }
diff --git a/Display.java b/Display.java
index fd403c4..23aef23 100644
--- a/Display.java
+++ b/Display.java
@@ -20,14 +20,17 @@ public class Display extends JFrame {
 
   @Override
   public void paint(Graphics g) {
+    // Doppelpuffer um Flackern zu verhindern
     BufferedImage b = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
     Graphics bg = b.getGraphics();
+
     bg.setColor(Color.BLACK);
     bg.fillRect(0, 0, width, height);
     bg.setColor(Color.WHITE);
     for (Drawable d : dc.get_drawables()) {
       d.draw(bg);
     }
+
     g.drawImage(b,0, 0, width, height, Color.BLACK, this);
   }
 }
diff --git a/Main.java b/Main.java
index 21794da..17a3314 100644
--- a/Main.java
+++ b/Main.java
@@ -24,7 +24,7 @@ public class Main implements DrawableCollection {
   public Main() {
     boids = new Boid[BOID_COUNT];
     for (int i = 0; i < BOID_COUNT; i++) {
-      boids[i] = new Boid(WIDTH, HEIGHT);
+      boids[i] = new Boid(WIDTH, HEIGHT, i % 16);
     }
 
     d = new Display(WIDTH, HEIGHT, this);
@@ -34,8 +34,8 @@ public class Main implements DrawableCollection {
     new Timer().scheduleAtFixedRate(new TimerTask() {
       @Override
       public void run() {
-        for (Boid b : boids) {
-          b.simulate();
+        for (int i = 0; i < BOID_COUNT; i++) {
+          boids[i].simulate(i % 16);
         }
         ChunkManager.clear();
         for (Boid b : boids) {
diff --git a/PhysicsObject.java b/PhysicsObject.java
index f912df1..a92eff6 100644
--- a/PhysicsObject.java
+++ b/PhysicsObject.java
@@ -29,7 +29,7 @@ public class PhysicsObject {
   }
 
   public void apply_force(float x, float y, float factor) {
-    if (x == 0 && y == 0)
+    if ((x == 0 && y == 0) || factor == 0)
       return;
     double len = Math.sqrt(Math.pow(x, 2) + Math.pow(y, 2));
     v_x += (x / len) * factor;