Woking (sort of)

src/Body.java

@@ -39,6 +39,7 @@ public class Body {
     public Vector gravitationalForce(Body b) {
         Vector direction = b.massCenter.minus(massCenter);
         double distance = direction.length();
+        if (distance == 0) return new Vector();
         direction.normalize();
         double force = Simulation.G * mass * b.mass / (distance * distance);
         return direction.times(force);

src/Octree.java

@@ -1,3 +1,6 @@
+import codedraw.CodeDraw;
+
+import java.awt.*;
 
 /**
  * + -> >= 0
@@ -44,6 +47,11 @@ public class Octree {
             bodies[i].move(forces[i]);
         }
     }
+
+    public void draw(CodeDraw cd) {
+        if (root == null) return;
+        root.draw(cd);
+    }
 }
 
 abstract class OctreeItem {
@@ -62,13 +70,16 @@ abstract class OctreeItem {
     abstract protected void preCalc();
 
     abstract protected Vector getForcesOnBody(Body body, double t);
+
+    abstract protected void draw(CodeDraw cd);
 }
 
 class OctreeNode extends OctreeItem {
-    private final OctreeItem[] children = new OctreeItem[8];;
+    private final OctreeItem[] children;
 
     protected OctreeNode(Vector center, double size) {
         super(center, size);
+        children = new OctreeItem[8];
     }
 
     @Override
@@ -77,7 +88,7 @@ class OctreeNode extends OctreeItem {
         if (num < 0) return this;
         OctreeItem oct = children[num];
         if (oct == null) {
-            children[num] = new OctreeLeaf(getOctantCenter(num), size / 2.0, body);
+            children[num] = new OctreeLeaf(getOctantCenter(num), size / 2, body);
         } else {
             children[num] = oct.add(body);
         }
@@ -116,9 +127,21 @@ class OctreeNode extends OctreeItem {
         return force;
     }
 
+    @Override
+    protected void draw(CodeDraw cd) {
+        for (OctreeItem child : children) {
+            if (child == null) continue;
+            child.draw(cd);
+        }
+        Vector p1 = center.minus(new Vector(size / 2));
+        Vector p2 = new Vector(size).minus(new Vector(Simulation.SECTION_SIZE / 2));
+        cd.setColor(Color.CYAN);
+        cd.drawRectangle(p1.getScreenX(cd), p1.getScreenY(cd), p2.getScreenX(cd), p2.getScreenY(cd));
+    }
+
     private int getOctantNum(Vector bodyPos) {
-        Vector pos = bodyPos.minus(this.center);
         if (!isInOctant(bodyPos)) return -1;
+        Vector pos = bodyPos.minus(this.center);
         return ((pos.getX() < 0) ? 1 : 0) | ((pos.getY() < 0) ? 2 : 0) | ((pos.getZ() < 0) ? 4 : 0);
     }
 
@@ -131,10 +154,10 @@ class OctreeNode extends OctreeItem {
 
     private Vector getOctantCenter(int octNum) {
         return this.center.plus(new Vector(
-                ((octNum & 1) != 0) ? -0.5 : 0.5,
+                ((octNum & 1) != 0) ? -1 : 1,
-                ((octNum & 2) != 0) ? -0.5 : 0.5,
+                ((octNum & 2) != 0) ? -1 : 1,
-                ((octNum & 4) != 0) ? -0.5 : 0.5)
+                ((octNum & 4) != 0) ? -1 : 1)
-                .times(this.size));
+                .times(this.size / 4));
     }
 }
 
@@ -148,15 +171,11 @@ class OctreeLeaf extends OctreeItem {
 
     @Override
     protected OctreeNode add(Body body) {
-        OctreeNode replace = new OctreeNode(this.center, this.size);
+        return new OctreeNode(this.center, this.size).add(this.body).add(body);
-        replace.add(this.body);
-        replace.add(body);
-        return replace;
     }
 
     @Override
     protected void preCalc() {
-        System.out.println(this.body);
         this.pseudoBody = new Body(this.body);
     }
 
@@ -164,4 +183,12 @@ class OctreeLeaf extends OctreeItem {
     protected Vector getForcesOnBody(Body body, double t) {
         return body.gravitationalForce(pseudoBody);
     }
+
+    @Override
+    protected void draw(CodeDraw cd) {
+        Vector p1 = center.minus(new Vector(size / 2));
+        Vector p2 = new Vector(size).minus(new Vector(Simulation.SECTION_SIZE / 2));
+        cd.setColor(Color.GREEN);
+        cd.drawRectangle(p1.getScreenX(cd), p1.getScreenY(cd), p2.getScreenX(cd), p2.getScreenY(cd));
+    }
 }

src/Simulation.java

@@ -62,7 +62,7 @@ public class Simulation {
             }
             bodies = mergedBodies;
             */
-            Octree octree = new Octree(new Vector(AU), SECTION_SIZE);
+            Octree octree = new Octree(new Vector(0, 0, 0), SECTION_SIZE);
             for (Body body : bodies) {
                 octree.add(body);
             }
@@ -73,6 +73,7 @@ public class Simulation {
                 for (Body body : bodies) {
                     body.draw(cd);
                 }
+                octree.draw(cd);
                 cd.show();
             }
         }