I need to use Verlet Rope in Box2d to simulate rope physics.
I tried to make rope physics in chipmunk, but it looks ugly!!
Can someone please give me a detailed explanation on how to enable Box2D?
I am on cocos2d-x 3.8
Can anyone who has successfully done give me a detailed walkthrough, I am trying my best!!
I’ve set the BOX2D_INTEGRATION to 1, and still am getting errors.
Im considering switching to Unity2D.
I think you need to do this:
COCOS2D_DEBUG=1 USE_FILE32API CC_ENABLE_CHIPMUNK_INTEGRATION=0
COCOS2D_DEBUG=1 USE_FILE32API CC_ENABLE_BOX2D_INTEGRATION=1
and disable CC_USE_PHYSICS in base/ccConfig.h
Thank you for the quick response.
I did everything you said. Still when I run my code, my Box2d is not appearing on the screen. (this is the same thing that was happening before)
Have you actually tried it yourself?
What do you mean by “not appearing on the screen”?
Are you using the Box2D API directly?
You cannot use the built-in physics wrapper if you want to use Box2D. That wrapper is only for Chipmunk.
You need to include the Box2D headers:
#include <Box2D/Box2D.h>
And then follow the users manual to get up to speed with the Box2D API: http://box2d.org/documentation.html
I am using Box2D with 3.8.1 and it works.
Sample Source Code
https://github.com/jimrange/HelloWorldSamples/tree/box2dSample
HelloWorld.h
#ifndef __HELLOWORLD_SCENE_H__
#define __HELLOWORLD_SCENE_H__
#include "cocos2d.h"
#include <Box2D/Box2D.h>
const static float PTM_RATIO = 32.0;
class HelloWorld : public cocos2d::Layer
{
public:
static cocos2d::Scene* createScene();
virtual bool init();
// a selector callback
void menuCloseCallback(cocos2d::Ref* pSender);
// implement the "static create()" method manually
CREATE_FUNC(HelloWorld);
b2World* _world;
b2Body *_groundBody;
void update(float dt);
};
#endif // __HELLOWORLD_SCENE_H__
HelloWorld.cpp
#include "HelloWorldScene.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;
}
Size visibleSize = Director::getInstance()->getVisibleSize();
Vec2 origin = Director::getInstance()->getVisibleOrigin();
/////////////////////////////
// 2. add a menu item with "X" image, which is clicked to quit the program
// you may modify it.
// add a "close" icon to exit the progress. it's an autorelease object
auto closeItem = MenuItemImage::create(
"CloseNormal.png",
"CloseSelected.png",
CC_CALLBACK_1(HelloWorld::menuCloseCallback, this));
closeItem->setPosition(Vec2(origin.x + visibleSize.width - closeItem->getContentSize().width/2 ,
origin.y + closeItem->getContentSize().height/2));
// create menu, it's an autorelease object
auto menu = Menu::create(closeItem, NULL);
menu->setPosition(Vec2::ZERO);
this->addChild(menu, 1);
/////////////////////////////
// 3. add your codes below...
// add a label shows "Hello World"
// create and initialize a label
auto label = Label::createWithTTF("Hello World", "fonts/Marker Felt.ttf", 24);
// position the label on the center of the screen
label->setPosition(Vec2(origin.x + visibleSize.width/2,
origin.y + visibleSize.height - label->getContentSize().height));
// add the label as a child to this layer
this->addChild(label, 1);
// add "HelloWorld" splash screen"
auto sprite = Sprite::create("HelloWorld.png");
// position the sprite on the center of the screen
sprite->setPosition(Vec2(visibleSize.width/2 + origin.x, visibleSize.height/2 + origin.y));
// add the sprite as a child to this layer
this->addChild(sprite, 0);
/////////////////////
b2Vec2 gravity;
gravity.Set(0.0f, -10.0f);
_world = new b2World(gravity);
b2BodyDef groundBodyDef;
groundBodyDef.position.Set(0,0);
_groundBody = _world->CreateBody(&groundBodyDef);
b2EdgeShape groundBox;
b2FixtureDef groundBoxDef;
groundBoxDef.shape = &groundBox;
groundBox.Set(b2Vec2(origin.x / PTM_RATIO, origin.y / PTM_RATIO), b2Vec2( (origin.x + visibleSize.width)/PTM_RATIO, origin.y / PTM_RATIO));
b2Fixture * fixture = _groundBody->CreateFixture(&groundBoxDef);
groundBox.Set(b2Vec2(origin.x / PTM_RATIO, origin.y / PTM_RATIO), b2Vec2(origin.x / PTM_RATIO , (origin.y + visibleSize.height) / PTM_RATIO));
_groundBody->CreateFixture(&groundBoxDef);
groundBox.Set(b2Vec2(origin.x / PTM_RATIO, (origin.y + visibleSize.height) / PTM_RATIO),
b2Vec2((origin.x + visibleSize.width) / PTM_RATIO, (origin.y + visibleSize.height) / PTM_RATIO));
_groundBody->CreateFixture(&groundBoxDef);
groundBox.Set(b2Vec2( (origin.x + visibleSize.width) / PTM_RATIO, (origin.y + visibleSize.height) / PTM_RATIO),
b2Vec2( (origin.x + visibleSize.width) / PTM_RATIO, origin.y / PTM_RATIO));
_groundBody->CreateFixture(&groundBoxDef);
b2Vec2 center = b2Vec2( (origin.x + visibleSize.width * 0.5) / PTM_RATIO, (origin.y + visibleSize.height * 0.5) / PTM_RATIO);
for (int i=0; i<10; i++)
{
Sprite *ball = Sprite::create("CloseNormal.png");
ball->setTag(1);
this->addChild(ball);
b2BodyDef ballBodyDef;
ballBodyDef.type = b2_dynamicBody;
ballBodyDef.position.Set(10.0 / PTM_RATIO * ((float)i + 1.0), center.y);
ballBodyDef.userData = ball;
b2Body *ballBody = _world->CreateBody(&ballBodyDef);
b2CircleShape circle;
circle.m_radius = ball->getContentSize().width * 0.5 / PTM_RATIO;
b2FixtureDef ballShapeDef;
ballShapeDef.shape = &circle;
ballShapeDef.density = 1.0f;
ballShapeDef.friction = 0.0f;
ballShapeDef.restitution = 1.0f;
b2Fixture * ballFixture = ballBody->CreateFixture(&ballShapeDef);
}
this->schedule(CC_SCHEDULE_SELECTOR(HelloWorld::update));
return true;
}
void HelloWorld::update(float dt)
{
int velocityIterations = 5;
int positionIterations = 1;
_world->Step(dt, velocityIterations, positionIterations);
for (b2Body* body = _world->GetBodyList(); body; body = body->GetNext())
{
if (body->GetUserData() != NULL) {
Sprite* sprite = (Sprite*)body->GetUserData();
Vec2 position = Vec2( body->GetPosition().x * PTM_RATIO, body->GetPosition().y * PTM_RATIO) ;
CCLOG("Position:%.2f,%.2f", position.x, position.y);
sprite->setPosition(position );
sprite->setRotation( -1 * CC_RADIANS_TO_DEGREES(body->GetAngle()) );
}
}
}
void HelloWorld::menuCloseCallback(Ref* pSender)
{
Director::getInstance()->end();
#if (CC_TARGET_PLATFORM == CC_PLATFORM_IOS)
exit(0);
#endif
}
Thank you! This code worked for me.
Finally, now I dont have to switch! XD