cocos2dx-v3.0-图形绘制-draw()函数

       cocos2dx已经封装了很多关于opengl的函数，可以方便的使用，在3.0v以前，是在draw编写绘制代码，3.0v以后，还是在draw函数里，但发生了点变化。

      先来看一下Node类关于draw函数的申明

     virtual void draw(Renderer *renderer, const Mat4& transform, uint32_t flags);        virtual void draw() final;

      第二函数已经被声明为final，也就是不能重载（C++11规定，final函数必需要加关键词virtual).所以不能再像老版本一样使用。

      重写第一个方法来绘制你自己的节点。

  被 TransitionFadeTR, TransitionSplitCols, TransitionTurnOffTiles, TransitionCrossFade, Sprite, LayerColor, Label, RenderTexture,SpriteBatchNode, PhysicsSprite, ProgressTimer, ParticleSystemQuad, ParticleBatchNode, TransitionScene, DrawNode, MotionStreak,VideoPlayer, TransitionPageTurn, AtlasNode , 以及 PhysicsDebugNode 重载.

    

   下面给出一个例子，先看结果图

 可以拖动四个结点改变曲线

声明代码

#ifndef __HELLOWORLD_SCENE_H__#define __HELLOWORLD_SCENE_H__#include "cocos2d.h"class HelloWorld : public cocos2d::Layer{public:    // there's no 'id' in cpp, so we recommend returning the class instance pointer    static cocos2d::Scene* createScene();    // Here's a difference. Method 'init' in cocos2d-x returns bool, instead of returning 'id' in cocos2d-iphone    virtual bool init();          // a selector callback    void menuCloseCallback(cocos2d::Ref* pSender);virtual void draw(cocos2d::Renderer *renderer, const cocos2d::Mat4 &transform, uint32_t flags) override;    // implement the "static create()" method manually    CREATE_FUNC(HelloWorld);private:cocos2d::Sprite *yellow, *bule, *orange, *red;bool onTouchBegan(cocos2d::Touch *touch, cocos2d::Event *event);void  onTouchMoved(cocos2d::Touch*touch, cocos2d::Event *event);};#endif // __HELLOWORLD_SCENE_H__

实现代码

// on "init" you need to initialize your instancebool 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 = LabelTTF::create("Hello World", "Arial", 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);red = Sprite::create("red.png");red->setPosition(10, 10);this->addChild(red,3);    yellow = Sprite::create("yellow.png");yellow->setPosition(200, 200);this->addChild(yellow, 3);bule = Sprite::create("bule.png");bule->setPosition(400, 400);this->addChild(bule, 3);orange = Sprite::create("orang.png");orange->setPosition(500, 500);this->addChild(orange, 4);auto listener = EventListenerTouchOneByOne::create();listener->onTouchBegan = CC_CALLBACK_2( HelloWorld::onTouchBegan,this);listener->onTouchMoved = CC_CALLBACK_2(HelloWorld::onTouchMoved, this);this->getEventDispatcher()->addEventListenerWithSceneGraphPriority(listener,bule);this->getEventDispatcher()->addEventListenerWithSceneGraphPriority(listener->clone(), orange);this->getEventDispatcher()->addEventListenerWithSceneGraphPriority(listener->clone(), yellow);this->getEventDispatcher()->addEventListenerWithSceneGraphPriority(listener->clone(), red);    return true;}void HelloWorld::menuCloseCallback(Ref* pSender){#if (CC_TARGET_PLATFORM == CC_PLATFORM_WP8) || (CC_TARGET_PLATFORM == CC_PLATFORM_WINRT)MessageBox("You pressed the close button. Windows Store Apps do not implement a close button.","Alert");    return;#endif    Director::getInstance()->end();#if (CC_TARGET_PLATFORM == CC_PLATFORM_IOS)    exit(0);#endif}void  HelloWorld::draw(Renderer* renderer, const Mat4 &transform, uint32_t flags){auto array = PointArray::create(10);ccDrawLine(Vec2(100, 100), Vec2(900, 100));ccDrawLine(Vec2(100, 100), Vec2(100, 600));array->addControlPoint(Vec2(100, 100));array->addControlPoint(red->getPosition());array->addControlPoint(bule->getPosition());array->addControlPoint(yellow->getPosition());array->addControlPoint(orange->getPosition());ccDrawCardinalSpline(array, 0, 100);}bool HelloWorld::onTouchBegan(cocos2d::Touch *touch, cocos2d::Event *event){auto sprite = static_cast<Sprite*>(event->getCurrentTarget());auto point = sprite->convertToNodeSpace(touch->getLocation());auto rect = Rect(0, 0, sprite->getContentSize().width, sprite->getContentSize().height);if (rect.containsPoint(poi