Wiki refresh (Hello Physics) (#162)

I am going through the beginner wiki pages and updating them so they are the same as the source code files in jme3test/helloworld. I will do the animation page once I master it and that will be more in depth because animation spans a couple of wiki pages so I will be consolidating tweaking multiple pages. 

In this we edit the Material lines, update the RigidBodyControl lines, update the initInputs, update the private ActionListener, update the initWall method, update the initCrosshairs method, and update some comments throughout. 

jme3test/helloworld source code:
https://github.com/jMonkeyEngine/jmonkeyengine/blob/master/jme3-examples/src/main/java/jme3test/helloworld/HelloPhysics.java

docs/modules/tutorials/pages/beginner/hello_physics.adoc

@@ -63,16 +63,13 @@ public class HelloPhysics extends SimpleApplication {
   private BulletAppState bulletAppState;
 
   /** Prepare Materials */
-  Material wall_mat;
-  Material stone_mat;
-  Material floor_mat;
+  private Material wall_mat;
+  private Material stone_mat;
+  private Material floor_mat;
 
-  /** Prepare geometries and physical nodes for bricks and cannon balls. */
-  private RigidBodyControl    brick_phy;
+  /** Prepare geometries for bricks and cannonballs. */
   private static final Box    box;
-  private RigidBodyControl    ball_phy;
   private static final Sphere sphere;
-  private RigidBodyControl    floor_phy;
   private static final Box    floor;
 
   /** dimensions used for bricks and wall */
@@ -97,27 +94,31 @@ public class HelloPhysics extends SimpleApplication {
     /** Set up Physics Game */
     bulletAppState = new BulletAppState();
     stateManager.attach(bulletAppState);
-    //bulletAppState.getPhysicsSpace().enableDebug(assetManager);
 
     /** Configure cam to look at scene */
     cam.setLocation(new Vector3f(0, 4f, 6f));
     cam.lookAt(new Vector3f(2, 2, 0), Vector3f.UNIT_Y);
-    /** Add InputManager action: Left click triggers shooting. */
-    inputManager.addMapping("shoot",
-            new MouseButtonTrigger(MouseInput.BUTTON_LEFT));
-    inputManager.addListener(actionListener, "shoot");
-    /** Initialize the scene, materials, and physics space */
+    /** Initialize the scene, materials, inputs, and physics space */
+    initInputs();
     initMaterials();
     initWall();
     initFloor();
     initCrossHairs();
   }
-
+  
+    /** Add InputManager action: Left click triggers shooting. */
+    private void initInputs() {
+     inputManager.addMapping("shoot", 
+              new MouseButtonTrigger(MouseInput.BUTTON_LEFT));
+     inputManager.addListener(actionListener, "shoot");
+  }
+  
   /**
    * Every time the shoot action is triggered, a new cannon ball is produced.
    * The ball is set up to fly from the camera position in the camera direction.
    */
-  private ActionListener actionListener = new ActionListener() {
+  final private ActionListener actionListener = new ActionListener() {
+  @Override
     public void onAction(String name, boolean keyPressed, float tpf) {
       if (name.equals("shoot") && !keyPressed) {
         makeCannonBall();
@@ -154,42 +155,42 @@ public class HelloPhysics extends SimpleApplication {
     floor_geo.setLocalTranslation(0, -0.1f, 0);
     this.rootNode.attachChild(floor_geo);
     /* Make the floor physical with mass 0.0f! */
-    floor_phy = new RigidBodyControl(0.0f);
+    RigidBodyControl floor_phy = new RigidBodyControl(0.0f);
     floor_geo.addControl(floor_phy);
     bulletAppState.getPhysicsSpace().add(floor_phy);
   }
 
   /** This loop builds a wall out of individual bricks. */
   public void initWall() {
-    float startpt = brickLength / 4;
+    float startX = brickLength / 4;
     float height = 0;
     for (int j = 0; j < 15; j++) {
       for (int i = 0; i < 6; i++) {
         Vector3f vt =
-         new Vector3f(i * brickLength * 2 + startpt, brickHeight + height, 0);
+         new Vector3f(i * brickLength * 2 + startX, brickHeight + height, 0);
         makeBrick(vt);
       }
-      startpt = -startpt;
+      startX = -startX;
       height += 2 * brickHeight;
     }
   }
 
-  /** This method creates one individual physical brick. */
-  public void makeBrick(Vector3f loc) {
+  /** Creates one physical brick. */
+  private void makeBrick(Vector3f loc) {
     /** Create a brick geometry and attach to scene graph. */
     Geometry brick_geo = new Geometry("brick", box);
     brick_geo.setMaterial(wall_mat);
     rootNode.attachChild(brick_geo);
     /** Position the brick geometry  */
     brick_geo.setLocalTranslation(loc);
-    /** Make brick physical with a mass > 0.0f. */
-    brick_phy = new RigidBodyControl(2f);
+    /* Make brick physical with a mass > 0. */
+    RigidBodyControl brick_phy = new RigidBodyControl(2f);
     /** Add physical brick to physics space. */
     brick_geo.addControl(brick_phy);
     bulletAppState.getPhysicsSpace().add(brick_phy);
   }
 
-  /** This method creates one individual physical cannon ball.
+  /** Creates one physical cannonball.
    * By default, the ball is accelerated and flies
    * from the camera position in the camera direction.*/
    public void makeCannonBall() {
@@ -199,25 +200,25 @@ public class HelloPhysics extends SimpleApplication {
     rootNode.attachChild(ball_geo);
     /** Position the cannon ball  */
     ball_geo.setLocalTranslation(cam.getLocation());
-    /** Make the ball physcial with a mass > 0.0f */
-    ball_phy = new RigidBodyControl(1f);
+    /* Make the ball physical with a mass > 0.0f */
+    RigidBodyControl ball_phy = new RigidBodyControl(1f);
     /** Add physical ball to physics space. */
     ball_geo.addControl(ball_phy);
     bulletAppState.getPhysicsSpace().add(ball_phy);
-    /** Accelerate the physcial ball to shoot it. */
+    /* Accelerate the physical ball to shoot it. */
     ball_phy.setLinearVelocity(cam.getDirection().mult(25));
   }
 
   /** A plus sign used as crosshairs to help the player with aiming.*/
   protected void initCrossHairs() {
-    guiNode.detachAllChildren();
-    guiFont = assetManager.loadFont("Interface/Fonts/Default.fnt");
-    BitmapText ch = new BitmapText(guiFont, false);
+    setDisplayStatView(false);
+    //guiFont = assetManager.loadFont("Interface/Fonts/Default.fnt");
+    BitmapText ch = new BitmapText(guiFont);
     ch.setSize(guiFont.getCharSet().getRenderedSize() * 2);
     ch.setText("+");        // fake crosshairs :)
     ch.setLocalTranslation( // center
-      settings.getWidth() / 2 - guiFont.getCharSet().getRenderedSize() / 3 * 2,
-      settings.getHeight() / 2 + ch.getLineHeight() / 2, 0);
+      settings.getWidth() / 2,
+      settings.getHeight() / 2, 0);
     guiNode.attachChild(ch);
   }
 }
@@ -261,7 +262,7 @@ In this "`shoot`" at the wall example, you use Geometries such as cannon balls a
 [source,java]
 ----
 
-  /** Prepare geometries and physical nodes for bricks and cannon balls. */
+  /** Prepare geometries for bricks and cannonballs. */
   private static final Box    box;
   private static final Sphere sphere;
   private static final Box    floor;
@@ -285,32 +286,23 @@ In this "`shoot`" at the wall example, you use Geometries such as cannon balls a
 
 === RigidBodyControl: Brick
 
-We want to create brick Geometries from those boxes. For each Geometry with physical properties, you create a RigidBodyControl.
-
-[source,java]
-----
-
-  private RigidBodyControl brick_phy;
-
-----
-
-The custom `makeBrick(loc)` methods creates individual bricks at the location `loc`. A brick has the following properties:
+We want to create brick Geometries from those boxes. The custom `makeBrick(loc)` methods creates individual bricks at the location `loc`. A brick has the following properties:
 
 *  It has a visible Geometry `brick_geo` (Box Shape Geometry).
-*  It has physical properties `brick_phy` (RigidBodyControl)
+*  It has physical properties `brick_phy` (RigidBodyControl). Since this is a Geometry with physical properties you create a RigidBodyControl.
 
 [source,java]
 ----
 
-  public void makeBrick(Vector3f loc) {
+  private void makeBrick(Vector3f loc) {
     /** Create a brick geometry and attach to scene graph. */
     Geometry brick_geo = new Geometry("brick", box);
     brick_geo.setMaterial(wall_mat);
     rootNode.attachChild(brick_geo);
     /** Position the brick geometry  */
     brick_geo.setLocalTranslation(loc);
-    /** Make brick physical with a mass > 0.0f. */
-    brick_phy = new RigidBodyControl(2f);
+    /* Make brick physical with a mass > 0. */
+    RigidBodyControl brick_phy = new RigidBodyControl(2f);
     /** Add physical brick to physics space. */
     brick_geo.addControl(brick_phy);
     bulletAppState.getPhysicsSpace().add(brick_phy);
@@ -348,12 +340,12 @@ You notice that the cannon ball is created in the same way, using the custom `ma
     rootNode.attachChild(ball_geo);
     /** Position the cannon ball  */
     ball_geo.setLocalTranslation(cam.getLocation());
-    /** Make the ball physcial with a mass > 0.0f */
-    ball_phy = new RigidBodyControl(1f);
+    /* Make the ball physical with a mass > 0.0f */
+    RigidBodyControl ball_phy = new RigidBodyControl(1f);
     /** Add physical ball to physics space. */
     ball_geo.addControl(ball_phy);
     bulletAppState.getPhysicsSpace().add(ball_phy);
-    /** Accelerate the physcial ball to shoot it. */
+    /* Accelerate the physical ball to shoot it. */
     ball_phy.setLinearVelocity(cam.getDirection().mult(25));
 
 ----
@@ -392,7 +384,7 @@ As before, you write a custom `initFloor()` method that creates a flat box with
     floor_geo.setLocalTranslation(0, -0.1f, 0);
     this.rootNode.attachChild(floor_geo);
     /* Make the floor physical with mass 0.0f! */
-    floor_phy = new RigidBodyControl(0.0f);
+    RigidBodyControl floor_phy = new RigidBodyControl(0.0f);
     floor_geo.addControl(floor_phy);
     bulletAppState.getPhysicsSpace().add(floor_phy);
   }
@@ -444,7 +436,8 @@ You define the actual action of shooting a new cannon ball as follows:
 [source,java]
 ----
 
-    private ActionListener actionListener = new ActionListener() {
+    final private ActionListener actionListener = new ActionListener() {
+    @Override
         public void onAction(String name, boolean keyPressed, float tpf) {
             if (name.equals("shoot") && !keyPressed) {
                 makeCannonBall();