画写球

#ifndef linePhysics_hpp

#define linePhysics_hpp

#include <stdio.h>

#include <iostream>

using namespace std;

#include "cocos2d.h"

USING_NS_CC;

struct _segment{

    Point p1;

    Point p2;

};

class LinePhysica : public Layer {

    

    

public:

    static Scene* createScene();

    bool init();

    CREATE_FUNC(LinePhysica);

    virtual bool onTouchBegan(Touch *touch, Event *unused_event);

    virtual void onTouchMoved(Touch *touch, Event *unused_event);

    virtual void onTouchEnded(Touch *touch, Event *unused_event);

    virtual void onTouchCancelled(Touch *touch, Event *unused_event);

    //一帧调用一次

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

//    或

   void update(float dt);

    

    

    void setPhysicsWorld(PhysicsWorld* world){_world = world;}

    

    

    

    

private:

    Point pre_point;

    Point cur_point;

    _segment seg;

    std::vector<_segment> segment;

    PhysicsWorld* _world;

};

#endif /* linePhysics_hpp */

#include "linePhysics.hpp"

Scene* LinePhysica::createScene()

{

    auto scene = Scene::createWithPhysics();

    auto layer = LinePhysica::create();

    layer->setPhysicsWorld(scene->getPhysicsWorld());

    scene->getPhysicsWorld()->setDebugDrawMask(PhysicsWorld::DEBUGDRAW_ALL);

    //设置重力

    scene->getPhysicsWorld()->setGravity(Vec2(0, -320));

    scene->addChild(layer);

    

    return scene;

}

bool LinePhysica::init()

{

    if (!Layer::init()) {

        return false;

    }

    

    auto visiableSize = Director::getInstance()->getVisibleSize();

    auto body = PhysicsBody::createEdgeBox(visiableSize,PHYSICSBODY_MATERIAL_DEFAULT,5);

    //设置恢复力和摩擦力

    body->getShape(0)->setRestitution(1.f);

    body->getShape(0)->setFriction(0);

    

    //创建一个碰撞图形

    auto edgeShape = Node::create();

    //将图形和刚刚创建的世界绑定

    //    edgeShape->addComponent(body);

    edgeShape->setPhysicsBody(body);

    

    //设置图形的位置在屏幕中间

    edgeShape->setPosition(Vec2(visiableSize.width/2, visiableSize.height/2));

    //添加涂层

    addChild(edgeShape);

    

    auto sp = Sprite::create("ball.png");

    auto body2 = PhysicsBody::PhysicsBody::createCircle(16);

//    body2->setMass(2);

    body2->setDynamic(true);

    body2->getShape(0)->setRestitution(1);

//    body2->getShape(0)->setFriction(0.2f);

    body2->setCategoryBitmask(1);//分类掩码

    body2->setCollisionBitmask(1);//碰撞掩码

    body2->setContactTestBitmask(1);//接触测试掩码

    sp->setPhysicsBody(body2);

    sp->setPosition(Vec2(visiableSize.width/2, visiableSize.height/2));

    this->addChild(sp);

    

    

    

    auto touch_listener = EventListenerTouchOneByOne::create();

    touch_listener->onTouchBegan = CC_CALLBACK_2(LinePhysica::onTouchBegan, this);

    touch_listener->onTouchMoved = CC_CALLBACK_2(LinePhysica::onTouchMoved, this);

    touch_listener->onTouchEnded = CC_CALLBACK_2(LinePhysica::onTouchEnded, this);

    touch_listener->onTouchCancelled = CC_CALLBACK_2(LinePhysica::onTouchCancelled, this);

    Director::getInstance()->getEventDispatcher()->addEventListenerWithSceneGraphPriority(touch_listener, this);

    

    this->scheduleUpdate();

    

    

    return true;

}

bool LinePhysica::onTouchBegan(Touch *touch, Event *unused_event)

{

    cout<<"begin!"<<endl;

    Point location = touch->getLocation();

    pre_point = cur_point = location;

    return true;

}

void LinePhysica::onTouchMoved(Touch *touch, Event *unused_event)

{

    cout<<"moved!"<<endl;

    Point location = touch->getLocation();

    cur_point = location;

    if((pre_point - cur_point).getLengthSq()>25){

        seg.p1=pre_point;

        seg.p2=cur_point;

        segment.push_back(seg);

        pre_point=cur_point;

    }

}

void LinePhysica::onTouchEnded(Touch *touch, Event *unused_event)

{

    Point location = touch->getLocation();

    cur_point = location;

    if((pre_point - cur_point).getLengthSq()>25){

        seg.p1=pre_point;

        seg.p2=cur_point;

        segment.push_back(seg);

        pre_point=cur_point;

    }

    cout<<"end!"<<endl;

}

void LinePhysica::onTouchCancelled(Touch *touch, Event *unused_event)

{

}

//void LinePhysica::draw(Renderer *renderer, const Mat4 &transform, uint32_t flags)

//

//{

//    

////    DrawPrimitives::setDrawColor4B(0, 255, 255, 255);

////    glLineWidth(4);

//    for (std::vector<_segment >::const_iterator i=segment.begin(); i!=segment.end(); i++)

//    {

////        DrawPrimitives::drawLine(i->p1, i->p2);

////        创建一个静态的线状刚体.

//        auto lineBody = PhysicsBody::createEdgeSegment(i->p1, i->p2);

//        auto edgeNode = Node::create();

//        edgeNode->setPhysicsBody(lineBody);

//        addChild(edgeNode);

//    }

//    segment.clear();

//    

//}

void LinePhysica::update(float dt)

{

    for (std::vector<_segment >::const_iterator i=segment.begin(); i!=segment.end(); i++)

    {

        //        DrawPrimitives::drawLine(i->p1, i->p2);

        //        创建一个静态的线状刚体.

        auto lineBody = PhysicsBody::createEdgeSegment(i->p1, i->p2);

        auto edgeNode = Node::create();

        edgeNode->setPhysicsBody(lineBody);

        addChild(edgeNode);

    }

    segment.clear();

}

可以参考https://blog.csdn.net/llkk890320/article/details/25886613

cocos2d-x 3.0开发笔记---物理引擎封装 Physics深入学习