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POAndroid AndEngine: handling Collission Detection properly
 

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  1. POAndroid AndEngine: handling Collission Detection properly
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    <p>I am working on a simple AndEngine game that involves the ff. sprites </p> <p>a.) tanks b.) soldiers c.) bombs</p> <p>I have a similar question located here: <a href="https://stackoverflow.com/questions/12532918/android-andengine-simple-sprite-collision">Android AndEngine: Simple sprite collision</a></p> <p>What the game looks like:</p> <p><img src="https://i.stack.imgur.com/7TayY.jpg" alt="enter image description here"></p> <p>However upon fixing the initial problem, another problem arose:</p> <p>When the bomb (spawns where the plane is currently at and goes down vertically until it reaches a target or floor, by means of mouse click) hits a target, say a soldier, the soldier sprite must detach and leave behind it a blood splatter sprite for 1 second, as well as an explosion sprite from the bomb. However, the game force closes giving an indexOutOfBoundError. I understand that this might probably be a discrepancy of sprite count between the bomb and its target causing an out of bound array error, but logCat isn't helping at all. </p> <pre><code>09-22 11:13:37.585: E/AndroidRuntime(735): FATAL EXCEPTION: UpdateThread 09-22 11:13:37.585: E/AndroidRuntime(735): java.lang.IndexOutOfBoundsException: Invalid index 5, size is 5 09-22 11:13:37.585: E/AndroidRuntime(735): at java.util.ArrayList.throwIndexOutOfBoundsException(ArrayList.java:251) 09-22 11:13:37.585: E/AndroidRuntime(735): at java.util.ArrayList.get(ArrayList.java:304) 09-22 11:13:37.585: E/AndroidRuntime(735): at org.andengine.entity.Entity.onManagedUpdate(Entity.java:1402) 09-22 11:13:37.585: E/AndroidRuntime(735): at org.andengine.entity.Entity.onUpdate(Entity.java:1167) 09-22 11:13:37.585: E/AndroidRuntime(735): at org.andengine.entity.Entity.onManagedUpdate(Entity.java:1402) 09-22 11:13:37.585: E/AndroidRuntime(735): at org.andengine.entity.scene.Scene.onManagedUpdate(Scene.java:284) 09-22 11:13:37.585: E/AndroidRuntime(735): at org.andengine.entity.Entity.onUpdate(Entity.java:1167) 09-22 11:13:37.585: E/AndroidRuntime(735): at org.andengine.engine.Engine.onUpdateScene(Engine.java:591) 09-22 11:13:37.585: E/AndroidRuntime(735): at org.andengine.engine.Engine.onUpdate(Engine.java:586) 09-22 11:13:37.585: E/AndroidRuntime(735): at org.andengine.engine.Engine.onTickUpdate(Engine.java:548) 09-22 11:13:37.585: E/AndroidRuntime(735): at org.andengine.engine.Engine$UpdateThread.run(Engine.java:820) </code></pre> <p>As seen here, logCat isn't giving an error on my code, but on the AndEngine itself, and that's most probably not the case.</p> <p>My new code that runs in the onCreateScene Update Handler (as per help with the linked previous problem above):</p> <pre><code>protected void checkSoldierCollision() { // TODO Auto-generated method stub int numBombs = bombGroup.getChildCount(); int numTroops = troopsGroup.getChildCount(); final ArrayList&lt;Sprite&gt; toBeDetached = new ArrayList&lt;Sprite&gt;(); for (int i = 0; i &lt; numBombs; i++) { Sprite s = (Sprite) bombGroup.getChildByIndex(i); for (int j = 0; j &lt; numTroops; j++) { Sprite s2 = (Sprite) troopsGroup.getChildByIndex(j); if (s.collidesWith(s2)) { /*Sprite splat = createSplat(); splat.setPosition(s.getX(), s.getY()); getEngine().getScene().attachChild(splat);*/ Sprite splode = createExplosion(); splode.setPosition(s.getX(), s.getY()); getEngine().getScene().attachChild(splode); // WARNING: cannot detach from the list //while looping through the list toBeDetached.add(s); toBeDetached.add(s2); } } } runOnUpdateThread(new Runnable() { @Override public void run() { for (Sprite s : toBeDetached) { s.detachSelf(); Sprite splode = createExplosion(); splode.setPosition(s.getX(), s.getY()); getEngine().getScene().attachChild(splode); } toBeDetached.clear(); } }); } </code></pre> <p>What I noticed that it can only be either a splat or an explosion for it not to have an error. If both splat and explosion were to populate the scene upon collision, an error occurs.</p> <p>Also, even if the bombs dont hit the soldiers (but still detaching and replaced with an explosion cloud when hitting the floor) it also gives a similar error:</p> <p>My createBomb function:</p> <pre><code> public Sprite createBomb(float x, float y) { Sprite bombSprite = new Sprite(x, y, this.mBombTextureRegion, getVertexBufferObjectManager()); MoveYModifier downModBomb = new MoveYModifier(1, 60, FLOOR); downModBomb.addModifierListener(new IModifierListener&lt;IEntity&gt;() { @Override public void onModifierStarted(IModifier&lt;IEntity&gt; pModifier, IEntity pItem) { } @Override public void onModifierFinished(IModifier&lt;IEntity&gt; pModifier, final IEntity pItem) { pItem.detachSelf(); AnimatedSprite explodeSprite = createExplosion(); explodeSprite.setPosition(pItem.getX(), FLOOR); getEngine().getScene().attachChild(explodeSprite); } }); bombSprite.registerEntityModifier(downModBomb); // register action return bombSprite; } </code></pre> <p>My onCreateScene bomb function and collision updateHandler:</p> <pre><code> scene.setOnSceneTouchListener(new IOnSceneTouchListener() { @Override public boolean onSceneTouchEvent(Scene pScene, TouchEvent pSceneTouchEvent) { if (pSceneTouchEvent.getAction() == TouchEvent.ACTION_UP) { runOnUiThread(new Runnable() { @Override public void run() { Sprite bomb = createBomb(f16Sprite.getX(), f16Sprite.getY()); bombGroup.attachChild(bomb); } }); return true; } return false; } }); // periodic checks scene.registerUpdateHandler(new IUpdateHandler() { @Override public void onUpdate(float pSecondsElapsed) { // checkTankCollision(); // checkSoldierBackCollision(); checkSoldierCollision(); } @Override public void reset() { } }); </code></pre> <p>My createExplosion method:</p> <pre><code> public AnimatedSprite createExplosion() { AnimatedSprite boomSprite = new AnimatedSprite(0, 0, this.mExplodeTextureRegion, getVertexBufferObjectManager()); DelayModifier delay = new DelayModifier(.3f); // delay in seconds, can // take float numbers .5 // seconds delay.addModifierListener(new IModifierListener&lt;IEntity&gt;() { @Override public void onModifierStarted(IModifier&lt;IEntity&gt; pModifier, IEntity pItem) { ((AnimatedSprite) pItem).animate(new long[] { 100, 100, 100 }, // durations/frame new int[] { 1, 2, 3 }, // which frames true); // loop } @Override public void onModifierFinished(IModifier&lt;IEntity&gt; pModifier, final IEntity pItem) { ((AnimatedSprite) pItem).detachSelf(); } }); boomSprite.registerEntityModifier(delay); // register action return boomSprite; } </code></pre> <p>How do I remedy this? Looping logic isn't entirely my strong point. I am also open on how to implement this alternatively.</p> <p>UPDATE: Just realized that even if the result of the collision is either splat or explosion, it doesn't matter, if the player keeps spamming bombs (like say 4-5 times) the entire game force closes.</p> <p>-It seems that there is an allowable number of bombing whenever an instance of a solder/tank is created. I have turned off the create explosion first whenever a bomb hits a soldier (so a bloodsplat would just remain in its place instead of both). It works ok, but exceed 4-6 bombs and the game closes. When a new soldier instance spawns (meaning when the old ones go off screen and detaches) the player is then given 4-6 bombs before the game force closes.</p>
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