Small Update

core/src/com/isharryh/arkpets/ArkPets.java

@@ -72,8 +72,9 @@ public void create() {
 		// Plane setup
 		plane = new Plane(SCR_W, config.display_margin_bottom-SCR_H, SCR_H * 0.75f);
 		plane.setFrict(SCR_W * 0.05f, SCR_W * 0.25f);
+		plane.setBounce(0);
 		plane.setObjSize(WD_W, -WD_H);
-		plane.setSpeedLimit(SCR_W * 0.25f, SCR_H * 0.75f);
+		plane.setSpeedLimit(SCR_W * 0.5f, SCR_H * 1f);
 		plane.changePosition(0, WD_postar.x, -WD_postar.y);
 		Gdx.graphics.setForegroundFPS(APP_FPS);
 		Gdx.input.setInputProcessor(this);
@@ -242,16 +243,40 @@ private boolean setWindowPos(int x, int y, boolean override) {
 	private HWND refreshWindowIdx() {
 		ArrayList<HWndCtrl> windowList = HWndCtrl.getWindowList(true);
 		HWND minWindow = null;
+		HWndCtrl[] line = new HWndCtrl[SCR_H];
+		int myPos = (int)(WD_poscur.x + WD_W / 2);
 		int minNum = 2048;
 		int myNum = getArkPetsWindowNum(APP_TITLE);
 		for (HWndCtrl hWndCtrl : windowList) {
+			// Find windows as ground
+			if ((getArkPetsWindowNum(hWndCtrl.windowText) == -1) && hWndCtrl.posLeft <= myPos && myPos <= hWndCtrl.posRight) {
+				// This window IS in the vertical line that the app lies.
+				if (hWndCtrl.posBottom > 0 && hWndCtrl.posTop < SCR_H) {
+					for (int h = hWndCtrl.posTop<0?0:hWndCtrl.posTop; h < (hWndCtrl.posBottom>SCR_H?SCR_H:hWndCtrl.posBottom); h++) {
+						if (line[h] == null)
+							line[h] = (h == hWndCtrl.posTop) ? hWndCtrl : new HWndCtrl();
+					}
+				}
+			}
+			// Find the last peer window.
 			if (getArkPetsWindowNum(hWndCtrl.windowText) > myNum && getArkPetsWindowNum(hWndCtrl.windowText) < minNum) {
 				minNum = getArkPetsWindowNum(hWndCtrl.windowText);
 				minWindow = hWndCtrl.hWnd;
 			}
 		}
-		minWindow = (minWindow == null) ? new HWND(Pointer.createConstant(-1)) : minWindow;
-		return minWindow;
+		minWindow = (minWindow == null) ? new HWND(Pointer.createConstant(-1)) : minWindow; // Set as the top window if there is no peer.
+		if (plane != null) {
+			// Reset barriers
+			plane.barriers.clear();
+			for (int h = 0; h < SCR_H; h++) {
+				HWndCtrl temp = line[h];
+				if (temp != null && temp.hWnd != null) {
+					plane.setBarrier(-temp.posTop, 0, SCR_W, false);
+					//System.out.println("Barrier at "+(-temp.posTop)+" is "+temp.windowText+" pos "+temp.posLeft+","+temp.posRight);
+				}
+			}
+		}
+		return minWindow; // Return the last peer window.
 	}
 
 	private int getArkPetsWindowNum(String title) {

core/src/com/isharryh/arkpets/utils/Plane.java

@@ -7,7 +7,6 @@
 
 import com.badlogic.gdx.math.Vector2;
 import com.badlogic.gdx.math.Vector3;
-import com.sun.jna.platform.win32.User32;
 
 
 public class Plane {
@@ -17,6 +16,7 @@ public class Plane {
     public ArrayList<Vector3> barriers;
     private Vector2 world;
     private Vector2 obj;
+    private float bounce = 0;
     private float gravity = 0;
     private float airFrict = 0;
     private float staticFrict = 0;
@@ -36,6 +36,7 @@ public Plane(int $worldWidth, int $worldHeight, float $gravity) {
         barriers = new ArrayList<Vector3>();
         world = new Vector2($worldWidth, $worldHeight);
         obj = new Vector2(0, 0);
+        bounce = 0;
         gravity = $gravity;
         airFrict = 0;
         staticFrict = 0;
@@ -51,6 +52,13 @@ public Plane(int $worldWidth, int $worldHeight) {
         this($worldWidth, $worldHeight, 0);
     }
 
+    /** Set the bounce coefficient.
+     * @param $bounce The ratio of Ek to be reserved after the bounce.
+     */
+    public void setBounce(float $bounce) {
+        bounce = $bounce > 1 ? 1 : ($bounce < 0 ? 0 : $bounce);
+    }
+
     /** Set the frictions.
      * @param $airFrict The acceleration of air friction (px/s^2).
      * @param $staticFrict The acceleration of static friction provided by the groud (px/s^2).
@@ -104,6 +112,12 @@ public void updatePosition(float $deltaTime) {
         position.set(limitX(deltaX + position.x), limitY(deltaY + position.y));
     }
 
+    /** Set a line barrier that can support the object.
+     * @param $posTop The y-position of the barrier.
+     * @param $posLeft The x-position of the barrier's left edge.
+     * @param $posRight The x-position of the barrier's right edge.
+     * @param $overCover Whether to set the highest priority to this barrier.
+     */
     public void setBarrier(float $posTop, float $posLeft, float $width, boolean $overCover) {
         if ($overCover)
             barriers.add(0, new Vector3($posLeft, $posTop, $width));
@@ -169,6 +183,10 @@ else if (position.y == TOP && speed.y > 0)
             speed.x = Math.signum(speed.x) * speedLimit.x;
         if (speedLimit.y != 0 && Math.abs(speed.y) > speedLimit.y)
             speed.y = Math.signum(speed.y) * speedLimit.y;
+        // Bounce
+        if (bounce != 0 && (position.x == borderLeft() || position.x == borderRight())) {
+            speed.x = (float)(Math.sqrt(speed.x * speed.x * bounce) * Math.signum(-speed.x));
+        }
     }
 
     /** Apply a friction to a velocity.