cocos2dx 利用随机数模拟雪花飘落、粒子系统

运行截图

随机数

注意随机种子的设定需要在for循环的外面

用到了cocos2dx的 CCRANDOM_0_1

/** @def CCRANDOM_0_1
returns a random float between 0 and 1
*/
#define CCRANDOM_0_1() ((float)rand()/RAND_MAX)

TIMEVAL psv;
gettimeofday(&psv, NULL);
// 初始化随机种子
// timeval是个结构体，里边有俩个变量，一个是以秒为单位的，一个是以微妙为单位的
unsigned rand_seed = (unsigned)(psv.tv_sec * 1000 + psv.tv_usec / 1000);    //都转化为毫秒
srand(rand_seed);

for (int i = 0; i < N; i++)
{
int a = 0;
int b = visibleSize.width;
float xt = CCRANDOM_0_1() * (b - a + 1) + a;

a = 0;
b = visibleSize.height;
float yt = CCRANDOM_0_1() * (b - a + 1) + a;

vx[i] = origin.x + xt;
vy[i] = origin.y + yt;

labels[i] = Label::createWithSystemFont("*", "Arial", 24);

// position the label on the center of the screen
labels[i]->setPosition(Point(vx[i], vy[i]));

// add the label as a child to this layer
this->addChild(labels[i], 1);
}

完整代码

.h

#ifndef __HELLOWORLD_SCENE_H__
#define __HELLOWORLD_SCENE_H__

#include <vector>

#include "cocos2d.h"

#define N 200

USING_NS_CC;

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);

// implement the "static create()" method manually
CREATE_FUNC(HelloWorld);
public:
virtual void update(float delta);

void menuStopCallback(cocos2d::Ref* pSender);
void menuSlowCallback(cocos2d::Ref* pSender);
void menuMidCallback(cocos2d::Ref* pSender);
void menuFastCallback(cocos2d::Ref* pSender);

MenuItemFont *stop;
//
MenuItemFont *slow;
//
MenuItemFont *mid;
//
MenuItemFont *fast;
public:
Size visibleSize;
Point origin;

Label* labels
;
float speed;
float vx
;
float vy
;
};

#endif // __HELLOWORLD_SCENE_H__

.cpp

#include "HelloWorldScene.h"
#include <cstdlib>
#include <ctime>

USING_NS_CC;

Scene* HelloWorld::createScene()
{
// 'scene' is an autorelease object
auto scene = Scene::create();

// 'layer' is an autorelease object
auto layer = HelloWorld::create();

// add layer as a child to scene
scene->addChild(layer);

// return the scene
return scene;
}

// on "init" you need to initialize your instance
bool HelloWorld::init()
{
//////////////////////////////
// 1. super init first
if ( !Layer::init() )
{
return false;
}

visibleSize = Director::getInstance()->getVisibleSize();
origin = Director::getInstance()->getVisibleOrigin();

// add a label shows "Hello World"
// create and initialize a label

#if 0
//LabelTTF* label = LabelTTF::create("1", "Arial", 24);
Label* label = Label::createWithSystemFont("1", "Arial", 24);

// position the label on the center of the screen
label->setPosition(Point(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);
#endif

TIMEVAL psv;
gettimeofday(&psv, NULL);
// 初始化随机种子
// timeval是个结构体，里边有俩个变量，一个是以秒为单位的，一个是以微妙为单位的
unsigned rand_seed = (unsigned)(psv.tv_sec * 1000 + psv.tv_usec / 1000);    //都转化为毫秒
srand(rand_seed);

for (int i = 0; i < N; i++)
{
int a = 0;
int b = visibleSize.width;
float xt = CCRANDOM_0_1() * (b - a + 1) + a;

a = 0;
b = visibleSize.height;
float yt = CCRANDOM_0_1() * (b - a + 1) + a;

vx[i] = origin.x + xt;
vy[i] = origin.y + yt;

labels[i] = Label::createWithSystemFont("*", "Arial", 24);

// position the label on the center of the screen
labels[i]->setPosition(Point(vx[i], vy[i]));

// add the label as a child to this layer
this->addChild(labels[i], 1);
}

speed = 1;

this->scheduleUpdate(); // 定时器
//
MenuItemFont::setFontSize(22);// 系统设定字体大小
stop = MenuItemFont::create("stop");
stop->setTarget(this, menu_selector(HelloWorld::menuStopCallback));
//
slow = MenuItemFont::create("slow");
slow->setColor(Color3B::RED);
slow->setTarget(this, menu_selector(HelloWorld::menuSlowCallback));
//
mid = MenuItemFont::create("mid");
mid->setTarget(this, menu_selector(HelloWorld::menuMidCallback));
//
fast = MenuItemFont::create("fast");
fast->setTarget(this, menu_selector(HelloWorld::menuFastCallback));

//创建一个菜单容器 把菜单栏目放上去
Menu *menu = Menu::create(stop, slow, mid, fast, NULL);
//显示菜单
this->addChild(menu);
//菜单的显示位置
menu->setPosition(Point(50,visibleSize.height - 100));
//设置栏目间的宽度距离
menu->alignItemsVerticallyWithPadding(10.0);

return true;
}

void HelloWorld::update(float delta)
{
for (int i = 0; i < N; i++)
{
vy[i] -= speed;//2.0;
if (vy[i] <= 0)
{
int a = 0;
int b = visibleSize.width;
vx[i] = origin.x + CCRANDOM_0_1() * (b - a + 1) + a;
vy[i] = visibleSize.height;
}
labels[i]->setPosition(Point(vx[i], vy[i]));
}
}

// 改变下落的速度
void HelloWorld::menuStopCallback(cocos2d::Ref* pSender)
{
this->unscheduleUpdate();
speed = -1.0;

stop->setColor(Color3B::RED);
slow->setColor(Color3B::WHITE);
mid->setColor(Color3B::WHITE);
fast->setColor(Color3B::WHITE);
}
void HelloWorld::menuSlowCallback(cocos2d::Ref* pSender)
{
if (speed < 0)
this->scheduleUpdate();
speed = 1.0;

stop->setColor(Color3B::WHITE);
slow->setColor(Color3B::RED);
mid->setColor(Color3B::WHITE);
fast->setColor(Color3B::WHITE);
}
void HelloWorld::menuMidCallback(cocos2d::Ref* pSender)
{
if (speed < 0)
this->scheduleUpdate();
speed = 3.0;

stop->setColor(Color3B::WHITE);
slow->setColor(Color3B::WHITE);
mid->setColor(Color3B::RED);
fast->setColor(Color3B::WHITE);
}
void HelloWorld::menuFastCallback(cocos2d::Ref* pSender)
{
if (speed < 0)
this->scheduleUpdate();
speed = 6.0;

stop->setColor(Color3B::WHITE);
slow->setColor(Color3B::WHITE);
mid->setColor(Color3B::WHITE);
fast->setColor(Color3B::RED);
}

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();
speed = 10;

#if (CC_TARGET_PLATFORM == CC_PLATFORM_IOS)
exit(0);
#endif
}

粒子系统实现snow

参考

cocos2dx中一些自定义的例子系统

http://www.2cto.com/kf/201409/333598.html

Particle System（粒子系统）讲解

http://www.cnblogs.com/shangdahao/archive/2012/04/14/2447571.html

bg.png



snow.png

#include "HelloWorldScene.h"
#include <cstdlib>
#include <ctime>

USING_NS_CC;

Scene* HelloWorld::createScene()
{
// 'scene' is an autorelease object
auto scene = Scene::create();

// 'layer' is an autorelease object
auto layer = HelloWorld::create();

// add layer as a child to scene
scene->addChild(layer);

// return the scene
return scene;
}

// on "init" you need to initialize your instance
bool HelloWorld::init()
{
//////////////////////////////
// 1. super init first
if ( !Layer::init() )
{
return false;
}

visibleSize = Director::getInstance()->getVisibleSize();
origin = Director::getInstance()->getVisibleOrigin();

auto bg = Sprite::create("bg.png");
bg->setPosition(Point(visibleSize.width / 2, visibleSize.height / 2));
this->addChild(bg);

#if 0
ParticleSystem* ps = ParticleSnow::createWithTotalParticles(9999);
//ParticleSystem* ps = ParticleSnow::create();
ps->setTexture(Director::getInstance()->getTextureCache()->addImage("snow.png"));
ps->setPosition(Point(visibleSize.width/2, visibleSize.height + 10));//生成的雪花从这个坐标往下落
//ps->setEmissionRate(10);
ps->setSpeed(200);
ps->setLife(10);
this->addChild(ps);
#endif

#if 1
auto particleSystem = ParticleSystemQuad::createWithTotalParticles(200);
//设置雪花粒子纹理图片
particleSystem->setTexture(TextureCache::getInstance()->addImage("snow.png"));
//设置发射粒子的持续时间-1表示永远持续
particleSystem->setDuration(-1);
//这个点是相对发射点，x正方向为右，y正方向为上 ,可以设置发射的方向
particleSystem->setGravity(Point(-10, -20));

//设置角度以及偏差
particleSystem->setAngle(90);
particleSystem->setAngleVar(360);

//设置径向加速度以及偏差
particleSystem->setRadialAccel(10);
particleSystem->setRadialAccelVar(0);

//设置粒子的切向加速度以及偏差
particleSystem->setTangentialAccel(30);
particleSystem->setTangentialAccelVar(30);

// 设置粒子初始化位置偏差
//particleSystem->setPosition(CCPoint(400, 500));
particleSystem->setPosVar(Point(400, 0));

//设置粒子生命期以及偏差
particleSystem->setLife(4);
particleSystem->setLifeVar(2);

//设置粒子开始时候旋转角度以及偏差
particleSystem->setStartSpin(30);
particleSystem->setStartSpinVar(60);

//设置结束时候的旋转角度以及偏差
particleSystem->setEndSpin(60);
particleSystem->setEndSpinVar(60);

//设置开始时候的颜色以及偏差
particleSystem->setStartColor(Color4F(1, 1, 1, 1));
//设置结束时候的颜色以及偏差
particleSystem->setEndColor(Color4F(0.9, 0.9, 0.9, 1));

//设置开始时候粒子大小以及偏差
particleSystem->setStartSize(30);
particleSystem->setStartSizeVar(0);

//设置粒子结束时候大小以及偏差
particleSystem->setEndSize(20.0f);
particleSystem->setEndSizeVar(0);

//设置每秒钟产生粒子的数量
particleSystem->setEmissionRate(100);

// 粒子系统位置
particleSystem->setPosition(Point(visibleSize.width * 0.75, visibleSize.height + 50));

this->addChild(particleSystem);
#endif

return true;
}

void HelloWorld::update(float delta)
{

}