axmol/samples/TestCpp/Classes/Box2DTest/Box2dTest.cpp

#include "Box2dTest.h"
#include "../testResource.h"

#define PTM_RATIO 32

enum {
    kTagParentNode = 1,
};

PhysicsSprite::PhysicsSprite()
: m_pBody(NULL)
{

}

void PhysicsSprite::setPhysicsBody(b2Body * body)
{
    m_pBody = body;
}

// this method will only get called if the sprite is batched.
// return YES if the physics values (angles, position ) changed
// If you return NO, then nodeToParentTransform won't be called.
bool PhysicsSprite::isDirty(void)
{
    return true;
}

// returns the transform matrix according the Chipmunk Body values
CCAffineTransform PhysicsSprite::nodeToParentTransform(void)
{
    b2Vec2 pos  = m_pBody->GetPosition();

    float x = pos.x * PTM_RATIO;
    float y = pos.y * PTM_RATIO;

    if ( isIgnoreAnchorPointForPosition() ) {
        x += m_tAnchorPointInPoints.x;
        y += m_tAnchorPointInPoints.y;
    }

    // Make matrix
    float radians = m_pBody->GetAngle();
    float c = cosf(radians);
    float s = sinf(radians);

    if( ! m_tAnchorPointInPoints.equals(CCPointZero) ){
        x += c*-m_tAnchorPointInPoints.x + -s*-m_tAnchorPointInPoints.y;
        y += s*-m_tAnchorPointInPoints.x + c*-m_tAnchorPointInPoints.y;
    }

    // Rot, Translate Matrix
    m_tTransform = CCAffineTransformMake( c,  s,
        -s,    c,
        x,    y );

    return m_tTransform;
}

Box2DTestLayer::Box2DTestLayer()
: m_pSpriteTexture(NULL)
{
    setTouchEnabled( true );
    setAccelerometerEnabled( true );

    CCSize s = CCDirector::sharedDirector()->getWinSize();
    // init physics
    this->initPhysics();
    // create reset button
    this->createResetButton();

    //Set up sprite
#if 1
    // Use batch node. Faster
    CCSpriteBatchNode *parent = CCSpriteBatchNode::create("Images/blocks.png", 100);
    m_pSpriteTexture = parent->getTexture();
#else
    // doesn't use batch node. Slower
    m_pSpriteTexture = CCTextureCache::sharedTextureCache()->addImage("Images/blocks.png");
    CCNode *parent = CCNode::create();
#endif
    addChild(parent, 0, kTagParentNode);


    addNewSpriteAtPosition(ccp(s.width/2, s.height/2));

    CCLabelTTF *label = CCLabelTTF::create("Tap screen", "Marker Felt", 32);
    addChild(label, 0);
    label->setColor(ccc3(0,0,255));
    label->setPosition(ccp( s.width/2, s.height-50));
    
    scheduleUpdate();
}

Box2DTestLayer::~Box2DTestLayer()
{
    delete world;
    world = NULL;
    
    //delete m_debugDraw;
}

void Box2DTestLayer::initPhysics()
{

    CCSize s = CCDirector::sharedDirector()->getWinSize();

    b2Vec2 gravity;
    gravity.Set(0.0f, -10.0f);
    world = new b2World(gravity);

    // Do we want to let bodies sleep?
    world->SetAllowSleeping(true);

    world->SetContinuousPhysics(true);

//     m_debugDraw = new GLESDebugDraw( PTM_RATIO );
//     world->SetDebugDraw(m_debugDraw);

    uint32 flags = 0;
    flags += b2Draw::e_shapeBit;
    //        flags += b2Draw::e_jointBit;
    //        flags += b2Draw::e_aabbBit;
    //        flags += b2Draw::e_pairBit;
    //        flags += b2Draw::e_centerOfMassBit;
    //m_debugDraw->SetFlags(flags);


    // Define the ground body.
    b2BodyDef groundBodyDef;
    groundBodyDef.position.Set(0, 0); // bottom-left corner

    // Call the body factory which allocates memory for the ground body
    // from a pool and creates the ground box shape (also from a pool).
    // The body is also added to the world.
    b2Body* groundBody = world->CreateBody(&groundBodyDef);

    // Define the ground box shape.
    b2EdgeShape groundBox;

    // bottom

    groundBox.Set(b2Vec2(0,0), b2Vec2(s.width/PTM_RATIO,0));
    groundBody->CreateFixture(&groundBox,0);

    // top
    groundBox.Set(b2Vec2(0,s.height/PTM_RATIO), b2Vec2(s.width/PTM_RATIO,s.height/PTM_RATIO));
    groundBody->CreateFixture(&groundBox,0);

    // left
    groundBox.Set(b2Vec2(0,s.height/PTM_RATIO), b2Vec2(0,0));
    groundBody->CreateFixture(&groundBox,0);

    // right
    groundBox.Set(b2Vec2(s.width/PTM_RATIO,s.height/PTM_RATIO), b2Vec2(s.width/PTM_RATIO,0));
    groundBody->CreateFixture(&groundBox,0);
}

void Box2DTestLayer::createResetButton()
{
    CCMenuItemImage *reset = CCMenuItemImage::create("Images/r1.png", "Images/r2.png", this, menu_selector(Box2DTestLayer::reset));

    CCMenu *menu = CCMenu::create(reset, NULL);

    CCSize s = CCDirector::sharedDirector()->getWinSize();

    menu->setPosition(ccp(s.width/2, 30));
    this->addChild(menu, -1);

}

void Box2DTestLayer::reset(CCObject* sender)
{
    CCScene* s = new Box2DTestScene();
    Box2DTestLayer* child = new Box2DTestLayer();
    s->addChild(child);
    child->release();
    CCDirector::sharedDirector()->replaceScene(s);
    s->release();
}

void Box2DTestLayer::draw()
{
    //
    // IMPORTANT:
    // This is only for debug purposes
    // It is recommend to disable it
    //
    CCLayer::draw();

    ccGLEnableVertexAttribs( kCCVertexAttribFlag_Position );

    kmGLPushMatrix();

    world->DrawDebugData();

    kmGLPopMatrix();
}

void Box2DTestLayer::addNewSpriteAtPosition(CCPoint p)
{
    CCLOG("Add sprite %0.2f x %02.f",p.x,p.y);
    CCNode* parent = getChildByTag(kTagParentNode);
    
    //We have a 64x64 sprite sheet with 4 different 32x32 images.  The following code is
    //just randomly picking one of the images
    int idx = (CCRANDOM_0_1() > .5 ? 0:1);
    int idy = (CCRANDOM_0_1() > .5 ? 0:1);
    PhysicsSprite *sprite = new PhysicsSprite();
    sprite->initWithTexture(m_pSpriteTexture, CCRectMake(32 * idx,32 * idy,32,32));
    sprite->autorelease();

    parent->addChild(sprite);
    
    sprite->setPosition( CCPointMake( p.x, p.y) );
    
    // Define the dynamic body.
    //Set up a 1m squared box in the physics world
    b2BodyDef bodyDef;
    bodyDef.type = b2_dynamicBody;
    bodyDef.position.Set(p.x/PTM_RATIO, p.y/PTM_RATIO);

    b2Body *body = world->CreateBody(&bodyDef);
    
    // Define another box shape for our dynamic body.
    b2PolygonShape dynamicBox;
    dynamicBox.SetAsBox(.5f, .5f);//These are mid points for our 1m box
    
    // Define the dynamic body fixture.
    b2FixtureDef fixtureDef;
    fixtureDef.shape = &dynamicBox;    
    fixtureDef.density = 1.0f;
    fixtureDef.friction = 0.3f;
    body->CreateFixture(&fixtureDef);

    sprite->setPhysicsBody(body);
}


void Box2DTestLayer::update(float dt)
{
    //It is recommended that a fixed time step is used with Box2D for stability
    //of the simulation, however, we are using a variable time step here.
    //You need to make an informed choice, the following URL is useful
    //http://gafferongames.com/game-physics/fix-your-timestep/
    
    int velocityIterations = 8;
    int positionIterations = 1;

    // Instruct the world to perform a single step of simulation. It is
    // generally best to keep the time step and iterations fixed.
    world->Step(dt, velocityIterations, positionIterations);
}

void Box2DTestLayer::ccTouchesEnded(CCSet* touches, CCEvent* event)
{
    //Add a new body/atlas sprite at the touched location
    CCSetIterator it;
    CCTouch* touch;

    for( it = touches->begin(); it != touches->end(); it++) 
    {
        touch = (CCTouch*)(*it);

        if(!touch)
            break;

        CCPoint location = touch->getLocation();
    
        addNewSpriteAtPosition( location );
    }
}

/*
void Box2DTestLayer::accelerometer(UIAccelerometer* accelerometer, CCAcceleration* acceleration)
{    
    static float prevX=0, prevY=0;

//#define kFilterFactor 0.05f
#define kFilterFactor 1.0f    // don't use filter. the code is here just as an example
    
    float accelX = (float) acceleration.x * kFilterFactor + (1- kFilterFactor)*prevX;
    float accelY = (float) acceleration.y * kFilterFactor + (1- kFilterFactor)*prevY;
    
    prevX = accelX;
    prevY = accelY;
    
    // accelerometer values are in "Portrait" mode. Change them to Landscape left
    // multiply the gravity by 10
    b2Vec2 gravity( -accelY * 10, accelX * 10);
    
    world->SetGravity( gravity );
}
*/

void Box2DTestScene::runThisTest()
{
    CCLayer* pLayer = new Box2DTestLayer();
    addChild(pLayer);
    pLayer->release();

    CCDirector::sharedDirector()->replaceScene(this);
}