Removed implementation classes

Leaves only the framework in the compiled clause.
Find the removed files in ../examples/misc/

examples/misc/PhysicsSystem.java

@@ -0,0 +1,37 @@
+package nz.ac.massey.javaecs;
+
+public class PhysicsSystem extends ECSSystem{
+    ECS gameEngine;
+    public PhysicsSystem(ECS gameEngine){
+        this.gameEngine = gameEngine;
+    }
+
+    @Override
+    void init() {}
+
+    @Override
+    void update() {}
+
+    void update(Double dt){
+        for (Integer entity : entities) {
+            Vec2D pos = (Vec2D)gameEngine.getComponentData(entity, Vec2D.class);
+            RidgidBody ridgidBody = (RidgidBody)gameEngine.getComponentData(entity, RidgidBody.class);
+            Gravity gravity = (Gravity)gameEngine.getComponentData(entity, Gravity.class);
+            // Firstly, add the result of the accelerative forces to the ridgidbody
+            ridgidBody.xdot += ridgidBody.xAcc * dt;
+            ridgidBody.ydot += ridgidBody.yAcc * dt;
+            
+            // Special case of gravity
+            if (gravity.terminalX < 0 || Math.abs(ridgidBody.xdot) < gravity.terminalX){
+                ridgidBody.xdot += gravity.x * dt;
+            }
+            if (gravity.terminalY < 0 || Math.abs(ridgidBody.ydot) < gravity.terminalY){
+                ridgidBody.ydot += gravity.y * dt;
+            }
+            
+            // Finally, move the vec2d by the new velocity
+            pos.x += ridgidBody.xdot * dt;
+            pos.y += ridgidBody.ydot * dt;
+        }
+    }
+}