Can you get a single object moving?

yes, a single object moves but multiple objects don’t..

Show us the code for moving a single object.

bool HelloWorld::init()
{
    //////////////////////////////
    // 1. super init first
    if ( !Layer::init() )
    {
        return false;
    } 

    b2Vec2 gravity;
    gravity.Set(0,0);
    world = new b2World(gravity);    
    world->SetContinuousPhysics(true);
    Size visibleSize = Director::getInstance()->getVisibleSize();
    Point origin = Director::getInstance()->getVisibleOrigin();
    
    fly = new Fly(this);     //When the fly constructor is called The sprite is created and position is set.
    fly->body1 = world->CreateBody(&(fly->ballBodyDef));
      
    this->schedule(schedule_selector(HelloWorld::FlyImage));
    return true;
}

void HelloWorld::FlyImage(float dt)
{    
    fly->FlyImage();
    world->Step(dt,8,3);
}

void Fly::FlyImage()
{   
    body1->SetLinearVelocity(b2Vec2(-60.0f,0.0f));
    sprite->setPosition(body1->GetPosition().x,body1->GetPosition().y);
}

What was Move[i] in Move[i]->MoveObj();

Is it a object?

yes..

According to the code..it’s the fly object…

For Single Object I used: fly->FlyImage();

For Multiple Objects I used: fly[i]->flyImage();

What’s the fly object, the problem?

There are two methods in the Fly class.
1) Constructor- where i set the sprite and the initial position.

​2) FlyImage – where the sprite is made to move by applying velocity.

The fly object is for calling the method FlyImage of the Fly class from HelloWorld class.

The problem is when this FlyImage method is called once, single sprite moves but when an array of fly object is created and the FlyImage method is called multiple times, the sprites dont move.

How are you creating the array of flying objects?

Creating an array of 5 fly objects.

for( int i =0;i<5i++){

     fly[i] = new Fly(this);    
     fly[i]->body1 = world->CreateBody(&(fly[i]->ballBodyDef));

}

How are you declaring the fly array object?

Fly *fly[5];

What’s the code for the  constructor       of the fly object.

Also for code, try using the code feature, see screenshot below

-----------------------HelloWorld.cpp---------------------------------------



#include "HelloWorldScene.h"
#include "Box2D\Box2D.h"
#include "Fly.h"

USING_NS_CC;

Scene* HelloWorld::createScene()
{
    // 'scene' is an autorelease object
    auto scene = Scene::create();
    
    // 'layer' is an autorelease object
    auto layer = HelloWorld::create();

    // add layer as a child to scene
    scene->addChild(layer);

    // return the scene
    return scene;
}

// on "init" you need to initialize your instance
bool HelloWorld::init()
{
    //////////////////////////////
    // 1. super init first
    if ( !Layer::init() )
    {
        return false;
    } 

	b2Vec2 gravity;
	gravity.Set(0,0);
	world = new b2World(gravity);	
	world->SetContinuousPhysics(true);
    Size visibleSize = Director::getInstance()->getVisibleSize();
    Point origin = Director::getInstance()->getVisibleOrigin();
	
	for(int i=0;i<5;i++){
		fly[i] = new Fly(this);
		fly[i]->body1 = world->CreateBody(&(fly[i]->ballBodyDef));
	}
	
	this->schedule(schedule_selector(HelloWorld::FlyImage));
	   
    return true;
}


void HelloWorld::FlyImage(float dt)
{		
	for(int i=0;i<5;i++){
		fly[i]->FlyImage();
	}
	world->Step(dt,8,3);
	CCLOG("Done");
}

#include "Fly.h"
#include "Box2D\Box2D.h"

USING_NS_CC;

Fly::Fly(cocos2d::Layer *layer)
{
	visibleSize = Director::getInstance()->getVisibleSize();
	origin = Director::getInstance()->getVisibleOrigin();

	//dupSprite = Sprite::create("rock.png");
	CCLOG("Creating");
		dupSprite = Sprite::create("rock.png");
		auto random = CCRANDOM_0_1()*200;
		auto random1 = CCRANDOM_0_1()*5;
		this->posX = 400 + random1 * random;
		this->posY = random;
		dupSprite->setPosition(posX,posY);
		CCLOG("X: %d Y: %d",posX,posY);
		layer->addChild(dupSprite);
		ballBodyDef.type = b2_kinematicBody;
		ballBodyDef.position = b2Vec2((dupSprite->getPosition().x),(dupSprite->getPosition().y));
		ballBodyDef.angle = 0;
		this->ballBodyDef.userData = dupSprite;
		circle.m_radius = (dupSprite->getContentSize().width/2)/32;
		ballFixDef.shape = &circle;
		ballFixDef.density = 10;
		ballFixDef.friction = 0.5f;
		ballFixDef.restitution = 0.8f;
		//body1->CreateFixture(&ballFixDef);

}

void Fly::FlyImage()
{
	body1->SetLinearVelocity(b2Vec2(-60.0f,0.0f));
	dupSprite->setPosition(body1->GetPosition().x,body1->GetPosition().y);
	
}

#include "Fly.h"
#include "Box2D\Box2D.h"

USING_NS_CC;

Fly::Fly(cocos2d::Layer *layer)
{
	visibleSize = Director::getInstance()->getVisibleSize();
	origin = Director::getInstance()->getVisibleOrigin();

	//dupSprite = Sprite::create("rock.png");
	CCLOG("Creating");
		dupSprite = Sprite::create("rock.png");
		auto random = CCRANDOM_0_1()*200;
		auto random1 = CCRANDOM_0_1()*5;
		this->posX = 400 + random1 * random;
		this->posY = random;
		dupSprite->setPosition(posX,posY);
		CCLOG("X: %d Y: %d",posX,posY);
		layer->addChild(dupSprite);
		ballBodyDef.type = b2_kinematicBody;
		ballBodyDef.position = b2Vec2((dupSprite->getPosition().x),(dupSprite->getPosition().y));
		ballBodyDef.angle = 0;
		this->ballBodyDef.userData = dupSprite;
		circle.m_radius = (dupSprite->getContentSize().width/2)/32;
		ballFixDef.shape = &circle;
		ballFixDef.density = 10;
		ballFixDef.friction = 0.5f;
		ballFixDef.restitution = 0.8f;
		//body1->CreateFixture(&ballFixDef);

}

void Fly::FlyImage()
{
	body1->SetLinearVelocity(b2Vec2(-60.0f,0.0f));
	dupSprite->setPosition(body1->GetPosition().x,body1->GetPosition().y);
	
}

Is body1 a variable in the Fly class?

Yes, Its a b2Body variable.

I declared it in Fly.h as b2Body *body1;

has it been initialised?

        fly[i]->body1 = world->CreateBody(&(fly[i]->ballBodyDef));

This is how it was initilased in HelloWorld.cpp. Refer the HelloWorld.cpp code above.

So if you don’t use an array and just use a single fly  object does it work?

Yes, it works for single object.

Try 5 objects but not as an array so 5 separate objects.