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“signal 11 (SIGSEGV), code 1” – (Cocos2dx, C++ with Android & Eclipse)

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The biggest drawback I’ve been having with Eclipse and cocos2dx (not sure if this also applies to Xcode …) I can think of is the annoying “Signal 11” error. But then I ran into this thread on StackOverFlow:

http://stackoverflow.com/questions/18436383/how-to-check-crash-log-using-android-ndk-in-cocos2d-x

I find the perfect answer in http://www.cocos2d-x.org/boards/6/topics/20437.

The solution is:

When you get errors like this on the LogCat, they are saved on $PROJECT_PATH/obj/local/armeabi where $PROJECT_PATH is the path to your cocos2d-x android project. To symbolicate the messages to something understandable, you can use the ndk-stack tool.

Open up the Terminal (or Cygwin, not sure though) and type in

cd $ANDROID_NDK
adb logcat | ./ndk-stack -sym $PROJECT_PATH/obj/local/armeabi

where:

$ANDROID_NDK is the path to your android NDK

$PROJECT_PATH is the path to your cocos2d-x android project

Wow! I just hit the jackpot! okay well time to switch over to my terminal and try this out. I then get the following crash dump:

********** Crash dump: **********
Build fingerprint: 'samsung/SC-04E/SC-04E:4.4.2/KOT49H/SC04EOMUFOB2:user/release-keys'
pid: 18875, tid: 18897, name: Thread-18051  >>> com.benji.etcetc <<<
signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr 00000000
Stack frame #00  pc 00000000  <unknown>
Stack frame #01  pc 000de0b9  /data/app-lib/com.benji.etcetc/libcocos2dcpp.so (GameScene::onTouchBegan(cocos2d::Touch*, cocos2d::Event*)+232): Routine GameScene::onTouchBegan(cocos2d::Touch*, cocos2d::Event*) at /Users/benji0110/Downloads/cocos2d-x-3.3/etcetc/proj.android/jni/../../Classes/GameScene.cpp:355
Crash dump is completed

Awesome! Finally according to my crash dump I was able to locate where my app crashes at line 355 .. it turns out I had deleted a game object at runtime and read that objects size, but because it was now destroyed the object no longer existed causing the program to terminate.

What a treat to end an awesome Friday^^

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Generate array of sprites (Cocos2dx, C++, Android)

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alright before i forget i better write this down (being an idiot that i am i’ll forget this later)

i have this image:

which when fired at, a single block explodes gracefully like a new born baby taking its first breath outside of a womans-anyway having 1 massive image like the one above to hold several dozen block images isn’t a good idea.

A better way to do this is to have each block:
block

stored in an array or vector, loop over then before the loop is finished, add each element into our layer.

In code this would look something like this:

Block header file .h

#ifndef __BLOCK_H__
#define __BLOCK_H__
 
#include "cocos2d.h"
 
class Block : public cocos2d::Sprite
{
 
// ....
 
protected:
    Sprite*                 block;
 
public:
    Block();                                                    //  constructor
    Sprite*                 generateBlock(int pos);             //  generate a block
};
 
 
#endif // __BLOCK_H__

Block Implementation file.cpp

// ... 
Sprite* Block::generateBlock(int pos) {
    Block        _block_obj;            // instantiate our block class
// ...
    block      = Sprite::create("block.png");
    block     -> setPosition(Vec2(visibleSize.width/2 + pos, visibleSize.height));
    return block;
}
 
// ...

Now in our game scene we can do something like this:

Game scene header file.h

// ...
std::array<cocos2d::Sprite*, 10> _blockArray;
void    generateBlocksThenAddToArray();                              // generate a block then add into our array
// ...

implementation file .cpp

/**
 *  generate a block then add into our array
 */
void Hoge::generateBlocksThenAddToArray() {
 
    for (int i = 0; i < 10; i++) {
        Sprite* _generatedBlock  = _block_obj.generateBlock((i * 100) / 2);
        _blockArray[i]        = _generatedBlock;
        this                 -> addChild(_generatedBlock);
    }
}

The magic happens in the for loop in Hoge::generateBlocksThenAddToArray() method.
We loop to a suitable range (10 in this case),generate a block from the block class, set its x position by multiplying it by 100 per iteration using i, then add the instantiated block object into our _blockArray with the loop count as its address, then finally add the generated block into our game scene.

There’s probably another (better) way to do this, and I’d love some input from other talented programmers out there so, please give me a shout in the comment section below!

Collision between enemy characters and bullets shot – (Cocos2dx, C++, Android)

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Last weekend I got really stuck with something for a game I am building that had to do with collisions. The link is here on Stackoverflow:

http://stackoverflow.com/questions/31352254/collision-between-enemy-characters-and-bullets-shot-cocos2dx-c-android

Would greatly appreciate it if anybody has a few ideas on how I can work around this idea ..

————————-

My problem is the collision detection that i wrote for my enemy character objects and bullet objects.

The symtoms:
When 1 enemy character spawns and i shoot it with my bullets, the enemy character is destroyed as normal. But, if 2 or more enemy characters spawn and i shoot the first enemy that was spawned it does nothing. The last character that was spawned and shot is destroyed without issue.

How i tried to fix it:
I decided to give each enemy character a unique ID by creating an int variable and randomize it each time an enemy is spawned. This ensures me that each enemy character object will definately have a unique identifier so that if i shoot them, I can somehow match that unique ID with my bullet.

However, I dont know how to work around that. The code below just deletes every enemy character associated with any randomized tags

My question:
How can I set my bullet objects to hold every unique ID of my enemy characters, so that when the bullet hits one (doesn’t matter which specific order) it will search then compare the unique IDs it has to the enemy character ID it has shot?

Apologies if my question is unclear or if my coding style is horrible.

GameScene.cpp

/**
 * @param ENEMY_SPAWN_FREQUENCY value is 0.002, set to make them spawn automatically every few seconds
 */
void GameScene::updateScheduler() {
    this -> scheduleUpdate();
    this -> schedule(schedule_selector(GameScene::spawnEnemyCharacter),      ENEMY_SPAWN_FREQUENCY * visibleSize.width);
}

// ...

bool GameScene::onTouchBegan(cocos2d::Touch* touch, cocos2d::Event* event) {

    // fire button
    auto target = (Sprite*)this -> getChildByTag(FIRE_BUTTON_TAG);
    Rect rect   = target        -> getBoundingBox();
    Point p     = touch         -> getLocation();

    // initialize bullets
    if (rect.containsPoint(p)) {
        GameScene::spawnBullets(PLAYER_TAG, playerCharacter->getPositionX(), playerCharacter->getPositionY()+100, 0, REFERENCE_SIZE_Y);
        return true;
    }

    // ...

    return false;
}

// ... somewhere below my GameScene.cpp class

void GameScene::spawnBullets(int shooter_id, int x, int y, int p_x, int p_y) {

    // load bullet sprites. 
    SpriteFrameCache::getInstance() -> addSpriteFramesWithFile("bullets.plist");

    // ... 

    auto bulletBody   = PhysicsBody::createBox(bullet_sprite -> getContentSize());
    bulletBody       -> setDynamic(true);
    bulletBody       -> setGravityEnable(false);
    bulletBody       -> setCollisionBitmask(BULLET_COLLISION_BITMASK);
    bulletBody       -> setContactTestBitmask(true);

    bullet_sprite    -> setPhysicsBody(bulletBody);
    bullet_sprite    -> setPosition(Point( x, y));
    bullet_sprite    -> setScale(0.2f);
    bullet_sprite    -> setTag(BULLET_TAG);
    this             -> addChild(bullet_sprite);

    // animate bullet object so that it shoots
    bullet_obj.fireBullet(bullet_sprite, p_x, p_y);
}

// ... somewhere further down this class i define my enemy characters to be spawned as enemy objects in the below method

void GameScene::spawnEnemyCharacter(float dt) {
    int random_tag = rand();        // ensure that each enemy character object has a unique random id as its tag
    enemyCharacter_obj.spawnEnemy(this, random_tag);
    enemy_tags.push_back(random_tag);

// ... destroy enemy characters if hit by bullet:

bool GameScene::onContactBegin( cocos2d::PhysicsContact &contact ) {
    PhysicsBody *a = contact.getShapeA() -> getBody();
    PhysicsBody *b = contact.getShapeB() -> getBody();

    if (BULLET_COLLISION_BITMASK == a->getCollisionBitmask() && ENEMY_COLLISION_BITMASK == b-> getCollisionBitmask() ||
        BULLET_COLLISION_BITMASK == b->getCollisionBitmask() && ENEMY_COLLISION_BITMASK == a-> getCollisionBitmask() ) {

        // delete enemys with random tag
        for (std::vector<int>::iterator itl = enemy_tags.begin(); itl != enemy_tags.end(); ++itl) {
            enemyCharacter_obj.destroyEnemyCharacter(this, *itl);
        }    
        this -> removeChild(bullet_sprite);
    }

    return true;
}

Bullet.cpp

void Bullet::fireBullet(Sprite* bullet_sprite, int x, int y) {
    auto bulletAction  = Sequence::create( MoveBy::create(BULLETSPEED, Point(x, y)), CallFuncN::create( CC_CALLBACK_1(Bullet::doRemoveFromParentAndCleanup, this, true)), NULL);
    bullet_sprite     -> runAction(bulletAction);
}

And now my enemy character class:

void EnemyCharacter::spawnEnemy(cocos2d::Layer* layer, int random_tag) {

    // データ読み込み
    SpriteFrameCache::getInstance() -> addSpriteFramesWithFile("enemies.plist");

    // 敵キャラクター
    enemyCharacter   = Sprite::createWithSpriteFrameName("enemy_1.png");
    auto enemyCharacterBody  = PhysicsBody::createBox(enemyCharacter -> getContentSize() / 5);

    // ...

    auto enemyCharacterPosition = (random * visibleSize.height ) + ( enemyCharacter -> getContentSize().height / 2);
    enemyCharacterBody         -> setDynamic(false);
    enemyCharacterBody         -> setCollisionBitmask(ENEMY_COLLISION_BITMASK);
    enemyCharacterBody         -> setContactTestBitmask(true);
    enemyCharacter             -> setScale(0.3f);
    enemyCharacter             -> setTag(random_tag);
    enemyCharacter             -> setPhysicsBody(enemyCharacterBody);
    enemyCharacter             -> setPosition( Point( ((random * visibleSize.width) + (enemyCharacter->getContentSize().width / 2)), visibleSize.height ) );
    layer                 -> addChild(enemyCharacter);

    // ...
}

// .. further down this class 

void EnemyCharacter::destroyEnemyCharacter(cocos2d::Layer* layer, int randomized_tag) {
    layer-> removeChild(layer -> getChildByTag(randomized_tag));
}

Fatal signal 6 (SIGABRT) at … (Cocos2dx 3.x on Android with C++) + Eclipse

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While it makes sense to use if statements its also blimin’ messy once you have so many conditions and editing the code later becomes messy, which eventually leads to bugs and hours of headaches.

I had an array like so:

MyClass::Constructor()
: MyArray({"C++", "C#", "Objective-C", "C"})
{
    // コンストラクター
}

Then I had to loop through this and tried to optimize my code so that instead of having something like this:

if (strcmp(MyArray,"C++") == 0){
    CCLog("array has C++");
} 
else if (strcmp(MyArray,"C#") == 0){
    CCLog("array has C#");
} 
if (strcmp(MyArray,"Objective-C") == 0){
    CCLog("array has Objective-C");
} 
if (strcmp(MyArray,"C") == 0){
    CCLog("array has C");
} 

I could turn it into something like this:

for (int i = 0; i < sizeof(MyArray); i++) {
    switch(i) {
        case 0: CCLog ("array has C++"); break;
        case 1: CCLog ("array has C#"); break;
        case 2: CCLog ("array has Objective-C"); break;
        case 3: CCLog ("array has C"); break;
    }

But the problem occurs when I get this error message:
Fatal signal 6 (SIGABRT) at …

I tried to print all the values of my array and commented out the switch statement and it seems that my loop will go through the array, but then read it from start to finish again and output (null)

The solution
I ended up not using sizeof, but just changed the above code to this:

for (int i = 0; i < MyArray.size(); i++) {
    switch(i) {
        case 0: CCLog ("array has C++"); break;
        case 1: CCLog ("array has C#"); break;
        case 2: CCLog ("array has Objective-C"); break;
        case 3: CCLog ("array has C"); break;
    }

Then recompiled and finally I was able to get my loop to work properly without issue.

Not really sure what sizeof really means, but i had assumed it worked the same as .size() and guessed wrong.