Cocos2d入门--3--小球运动

本章直接上源代码。内容不难，主要就是

HelloWorldScene.h文件：

 1 #ifndef __HELLOWORLD_SCENE_H__
 2 #define __HELLOWORLD_SCENE_H__
 3  4 #include "cocos2d.h"  5  6 class HelloWorld : public cocos2d::Layer
 7 {
 8 protected:
 9 float _angle;
10  cocos2d::Vec2 _vec;
11 public:
12 static cocos2d::Scene* createScene();
13 14 virtual bool init();
15 16 // a selector callback 17 void menuCloseCallback(cocos2d::Ref* pSender);
18 19 // implement the "static create()" method manually 20  CREATE_FUNC(HelloWorld);
21 22 virtual void update(float dt);
23 private:
24 //获取屏幕可视范围 25 float width_L;
26 float width_R;
27 cocos2d::DrawNode* ball;
28 };
29 30 #endif // __HELLOWORLD_SCENE_H__

HelloWorldScene.cpp文件：

 1 // on "init" you need to initialize your instance  2 bool HelloWorld::init()
 3 {
 4 //////////////////////////////
 5 // 1. super init first  6 if ( !Layer::init() )
 7  {
 8 return false;
 9  }
10 11 Size visibleSize = Director::getInstance()->getVisibleSize();
12 Vec2 origin = Director::getInstance()->getVisibleOrigin();
13 width_L = origin.x;
14 width_R = origin.x + visibleSize.width;
15 16 ball = DrawNode::create();
17 ball -> drawDot(Vec2(0, 0), 4, Color4F(1.0f, 1.0f, 1.0f, 1.0f));
18 19  addChild(ball);
20 ball -> setPosition(origin.x + visibleSize.width/2,origin.y + visibleSize.height/2);
21 22 //action相关的运动我们一般不是用来做游戏的运动，一般用来做游戏的变化效果。因为action不能很好的用来表现出游戏的效果
23 // dot -> runAction(RepeatForever::create(MoveBy::create(0.2, _vec*100)));
24 //
25  scheduleUpdate();
26 return true;
27 }
28 29 void HelloWorld::update(float dt){
30 ball -> setPositionX(ball->getPositionX()+5);
31 if (ball->getPositionX()<width_L-ball->getContentSize().width/2 32 || ball->getPositionX()>width_R+ball->getContentSize().width/2) {
33 ball->setPositionX(-ball->getContentSize().width/2);
34  }
35 }

然后实现的效果：