axmol/samples/TestCpp/Classes/TouchesTest/Ball.cpp

#include "Ball.h"
#include "Paddle.h"

Ball::Ball(void)
{
}

Ball::~Ball(void)
{
}

float Ball::radius()
{
    return getTexture()->getContentSize().width / 2;
}

Ball* Ball::ballWithTexture(CCTexture2D* aTexture)
{
    Ball* pBall = new Ball();
    pBall->initWithTexture(aTexture);
    pBall->autorelease();

    return pBall;
}

void Ball::move(float delta)
{
    CCSize size = CCDirector::sharedDirector()->getWinSize();

    this->setPosition( ccpAdd(getPosition(), ccpMult(m_velocity, delta)) );
    
    if (getPosition().x > size.width - radius()) 
    {
        setPosition( ccp( size.width - radius(), getPosition().y) );
        m_velocity.x *= -1;
    } 
    else if (getPosition().x < radius()) 
    {
        setPosition( ccp(radius(), getPosition().y) );
        m_velocity.x *= -1;
    }
}

void Ball::collideWithPaddle(Paddle* paddle)
{
    CCRect paddleRect = paddle->rect();
    paddleRect.origin.x += paddle->getPosition().x;
    paddleRect.origin.y += paddle->getPosition().y;
    
    float lowY = CCRect::CCRectGetMinY(paddleRect);
    float midY = CCRect::CCRectGetMidY(paddleRect);
    float highY = CCRect::CCRectGetMaxY(paddleRect);
    
    float leftX = CCRect::CCRectGetMinX(paddleRect);
    float rightX = CCRect::CCRectGetMaxX(paddleRect);
    
    if (getPosition().x > leftX && getPosition().x < rightX) {
    
        bool hit = false;
        float angleOffset = 0.0f; 
        
        if (getPosition().y > midY && getPosition().y <= highY + radius()) 
        {
            setPosition( CCPointMake(getPosition().x, highY + radius()) );
            hit = true;
            angleOffset = (float)M_PI / 2;
        }
        else if (getPosition().y < midY && getPosition().y >= lowY - radius()) 
        {
            setPosition( CCPointMake(getPosition().x, lowY - radius()) );
            hit = true;
            angleOffset = -(float)M_PI / 2;
        }
        
        if (hit) 
        {
            float hitAngle = ccpToAngle(ccpSub(paddle->getPosition(), getPosition())) + angleOffset;
            
            float scalarVelocity = ccpLength(m_velocity) * 1.05f;
            float velocityAngle = -ccpToAngle(m_velocity) + 0.5f * hitAngle;
            
            m_velocity = ccpMult(ccpForAngle(velocityAngle), scalarVelocity);
        }
    }    
}