Physics update in cocos2d-x v3 - c++

Question

I'm developing a game, using cocos2d-x 3.1.1 on Linux, that is going to have physics support.
I'm still at at the basics, but I'm already having many headaches.
The posted code is essentially what i have done so far, a ball influenced by gravity and a random velocity vector.
The problem is the simulation seems to never start, even if the sprite is rendered correctly. The ball does not move, in fact the position of the body is always the same (i log it). I tried to debug the application and to move blocks of code in other functions, without results.
Menu.cpp
#include "Menu.h"
#include "cocos2d.h"
#include <time.h>
#include <math.h>
#define COCOS2D_DEBUG 1
USING_NS_CC;
ScenaMenu *ScenaMenu::createWithPhysics() {
ScenaMenu *ret = new ScenaMenu();
if (ret && ret->initWithPhysics()) {
ret->autorelease();
return ret;
}
else {
CC_SAFE_DELETE(ret);
return nullptr;
}
}
ScenaMenu::ScenaMenu() {
frameSize = Director::getInstance()->getOpenGLView()->getFrameSize();
}
ScenaMenu::~ScenaMenu() {}
void ScenaMenu::onEnter() {
Scene::onEnter();
fisica = this->getPhysicsWorld();
fisica->setDebugDrawMask(PhysicsWorld::DEBUGDRAW_ALL);
fisica->setGravity(Vec2(0, -10.0f));
Texture2D::TexParams texParams = { GL_LINEAR_MIPMAP_LINEAR, GL_LINEAR, GL_CLAMP_TO_EDGE, GL_CLAMP_TO_EDGE };
LayerColor *layerMenu = LayerColor::create(Color4B(255, 255, 255, 255));
layerMenu->setContentSize(frameSize);
textureSfera = Director::getInstance()->getTextureCache()->addImage("sfera2.png");
textureSfera->setTexParameters(&texParams);
textureSfera->generateMipmap();
float angolo;
srand(time(NULL));
PhysicsMaterial mat = PhysicsMaterial(1, 1, 0);
PhysicsBody *bodyFisica;
bodyFisica = PhysicsBody::createCircle(layerMenu->getContentSize().width * 0.1, mat, Vec2::ZERO);
angolo = (rand() % 628) / 100.0f;
bodyFisica->setVelocity(Vec2(10 * cos(angolo), 10 * sin(angolo)));
spriteSfera = Sprite::createWithTexture(textureSfera);
spriteSfera->setScale((layerMenu->getContentSize().width * 0.33) / spriteSfera->getContentSize().width);
spriteSfera->setPosition(layerMenu->getContentSize().width * 0.5, layerMenu->getContentSize().height * 0.5);
spriteSfera->setPhysicsBody(bodyFisica);
this->addChild(layerMenu);
layerMenu->addChild(spriteSfera);
}
void ScenaMenu::update(float dt) {
log("POS %f", spriteSfera->getPhysicsBody()->getPosition().y);
}
AppDelegate.cpp
#include "AppDelegate.h"
#include "Menu.h"
USING_NS_CC;
AppDelegate::AppDelegate() {
}
AppDelegate::~AppDelegate()
{
}
bool AppDelegate::applicationDidFinishLaunching() {
auto director = Director::getInstance();
auto glview = director->getOpenGLView();
if(!glview) {
glview = GLView::create("Test");
director->setOpenGLView(glview);
}
Size frameSize = Size(540, 960);
cocos2d::Size designResolutionSize = Size(1080, 1920);
glview->setDesignResolutionSize(designResolutionSize.width, designResolutionSize.height, ResolutionPolicy::FIXED_WIDTH);
glview->setFrameSize(frameSize.width, frameSize.height);
director->setDisplayStats(true);
director->setAnimationInterval(1.0 / 60);
ScenaMenu *scenaMenu = ScenaMenu::createWithPhysics();
director->runWithScene(scenaMenu);
return true;
}
// This function will be called when the app is inactive. When comes a phone call,it's be invoked too
void AppDelegate::applicationDidEnterBackground() {
Director::getInstance()->stopAnimation();
// if you use SimpleAudioEngine, it must be pause
// SimpleAudioEngine::getInstance()->pauseBackgroundMusic();
}
// this function will be called when the app is active again
void AppDelegate::applicationWillEnterForeground() {
Director::getInstance()->startAnimation();
// if you use SimpleAudioEngine, it must resume here
// SimpleAudioEngine::getInstance()->resumeBackgroundMusic();
}