[Solved] Problems after upgrade to V3 RC using EventListenerPhysicsContact

cocos2d-x C++
#1

After upgrade to V3 RC, i got this errors:

#1

auto contactListener = EventListenerPhysicsContact::create();
**contactListener->onContactBegin = CC_CALLBACK_2(StageScene::onContactBegin);**

ERROR: No viable overloaded ‘=’

Why i cannot use it more? Can anyone help me?

#2

auto enemyBody = PhysicsBody::createBox(Size(enemy->getWidth(), enemy->getHeight()));
        
enemyBody->setRotationEnable(false);
enemyBody->setDynamic(false);
enemyBody->setGravityEnable(false);
enemy->setPhysicsBody(enemyBody);

Before update, with this code i move my objects manually and it generate Physic contact but is not affected by gravity. After update every object is going down :frowning: What i do to continue moving it manually and generate contact event when collide using cocos2d-x RC v3 ?

#2

#1 - Solved

Changed: CC_CALLBACK_2 to CC_CALLBACK_1

#3

Not solved :frowning:

It compile. But no event of collision happen.

My listener code:

auto contactListener = EventListenerPhysicsContact::create();
contactListener->onContactBegin = CC_CALLBACK_1(StageScene::onContactBegin, this);
_eventDispatcher->addEventListenerWithSceneGraphPriority(contactListener, this);

My receive event function:

bool StageScene::onContactBegin(const PhysicsContact& contact)
{
       CCLOG("Colisão detectada!");
       ....
}

I put a breakpoint on collision method but nothing happen and not generate log :frowning:

I get the code from here:
https://github.com/cocos2d/cocos2d-x/blob/develop/tests/cpp-tests/Classes/PhysicsTest/PhysicsTest.cpp
https://github.com/cocos2d/cocos2d-x/blob/develop/tests/cpp-tests/Classes/PhysicsTest/PhysicsTest.h

#5

Can anyone help me?

#6

You need to setContactTestBitmask for the body, because the listener only receive the contact event you want to receive. It ignore all the contact event by default.

#7

The problem #1 is solved, but only if i set dynamic = true.

But im using only collision from physic, i dont want that the objects is affected by gravity. Im trying it:

    auto coinBody = PhysicsBody::createBox(Size(coin->getWidth(), coin->getHeight()));
    coinBody->setRotationEnable(false);
    coinBody->setDynamic(false);
    coinBody->setGravityEnable(false);
    coinBody->setContactTestBitmask(0xFFFFFFFF);
    coin->setPhysicsBody(coinBody);

But with “coinBody->setDynamic(false);” no collision is detected, but the COIN position is updated manually(only position X), and when i set “coinBody->setDynamic(true);” the COIN if affected by gravity (but i set the gravity enable = false) and generate collision.

I cannot create a static object, that i update it manually and is not affected by gravity and generate collision event?

#8

@prchakal
Hi:
How to fix this: ERROR: No viable overloaded ‘=’

#9

@prchakal Hmm, maybe it’s a bug. I think you can set the gravity to 0. Try to use this: world->setGravity(Vect::ZERO)

#10

@rinzz Change CC_CALLBACK_2 to CC_CALLBACK_1, delete event param in callback function.

#11

The bug of setGravityEnable is conformed, I create an issue here:
http://cocos2d-x.org/issues/4424

#12

@boyu0 - For now, with Zero gravity, the problem not exists, i dont need it for this project. Thanks

rinzz - You need set your callback for ContactBegin with the CC_CALLBACK_1, and your method need have only one parameter, the PhysicsContact. Example:

CREATING THE LISTENER

auto contactListener = EventListenerPhysicsContact::create();
contactListener->onContactBegin = CC_CALLBACK_1(StageScene::onContactBegin, this);
_eventDispatcher->addEventListenerWithSceneGraphPriority(contactListener, this);

CREATING THE METHOD THAT WILL RECEIVE THE LISTENER EVENTS

bool StageScene::onContactBegin(const PhysicsContact& contact)
{
       CCLOG("Collision detected!");
       ....
}

Thanks.

#13

@boyu0
Then, whats going on with this gravity bug now ?
I downloaded the latest 3.0rc, and also encountered this problem just now …

We hace to set a ZERO gravity and simulate for each object ?

#14

Im my case i do it, i set gravity to zero and make it move manually without physics. I want use physics only for collision detect.

Cococs2d-X v3 RC has a bug on physics, but in my case i dont need wait solve the problem because my workaround solve my problem.