6/7 重新作scrolling background

這次要聽話，從最基本做起。

首先開始一個cocos2D + Box2D的專案。

修改邊界，製造斜度。將方塊改成circle，調整circle的摩擦係數(橘色底就是刪掉的，紅色字是更改的)：

-(void) addNewSpriteWithCoords:(CGPoint)p
{
    CCLOG(@"Add sprite %0.2f x %02.f",p.x,p.y);
   
    CCSpriteBatchNode *batch = (CCSpriteBatchNode*) [self getChildByTag:kTagBatchNode];
   
    //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);
    CCSprite *sprite = [CCSprite spriteWithBatchNode:batch rect:CGRectMake(32 * idx,32 * idy,32,32)];
    [batch addChild:sprite];
   
    sprite.position = ccp( 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);
    bodyDef.userData = sprite;
    b2Body *body = world->CreateBody(&bodyDef);
   
    // Define another box shape for our dynamic body.
    b2CircleShape dynamicCircle;
    dynamicCircle.m_radius = 0.5;//These are mid points for our 1m box
   
    // Define the dynamic body fixture.
    b2FixtureDef fixtureDef;
    fixtureDef.shape = &dynamicCircle;   
    fixtureDef.density = 1.0f;
    fixtureDef.friction = 0.1f;
    body->CreateFixture(&fixtureDef);
}

init方法裡面：
        // bottom
        groundBox.SetAsEdge(b2Vec2(0,90/PTM_RATIO), b2Vec2(screenSize.width/PTM_RATIO,0));

        CCSpriteBatchNode *batch = [CCSpriteBatchNode batchNodeWithFile:@"blocks.png" capacity:150];
        [self addChild:batch z:0 tag:kTagBatchNode];



目前為止都成功！

再來將整個邊界，拉長到兩倍！也就是把寬度增加到螢幕兩倍。

init方法裡面：
        // bottom
        groundBox.SetAsEdge(b2Vec2(0,90/PTM_RATIO), b2Vec2(screenSize.width * 2/PTM_RATIO,0));
        groundBody->CreateFixture(&groundBox,0);
       
        // top
        groundBox.SetAsEdge(b2Vec2(0,screenSize.height/PTM_RATIO),
                                b2Vec2(screenSize.width * 2/PTM_RATIO,screenSize.height/PTM_RATIO));
        groundBody->CreateFixture(&groundBox,0);
       
        // left
        groundBox.SetAsEdge(b2Vec2(0,screenSize.height/PTM_RATIO), b2Vec2(0,0));
        groundBody->CreateFixture(&groundBox,0);
       
        // right
        groundBox.SetAsEdge(b2Vec2(screenSize.width * 2/PTM_RATIO,screenSize.height/PTM_RATIO),
                            b2Vec2(screenSize.width * 2/PTM_RATIO,0));
        groundBody->CreateFixture(&groundBox,0);

再來是，畫面可以追著滾動的球跑！



待續....(XD)