版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/jackyvincefu/article/details/22665793
Cocos2d-x的粒子系统是通过加载plist生成的。plist包含两部分内容：粒子系统属性和粒子纹理。然而每次调用create都会对plist进行读取解析，如果重复地使用同一个粒子效果，这样的调用明显是低效冗余的。所以我们要做的是，将粒子系统属性和粒子纹理分别抽出。
（1）将粒子系统属性预加载并全局保存，避免每次进行读取。
（2）粒子纹理可视且可以进行纹理打包，加载粒子纹理就和加载普通的图片一样。
本文通过增加ParticleSystemQuad的接口实现对粒子系统属性和纹理帧的直接载入，来提高粒子系统的加载效率和实现内存纹理的优化。
1.ParticleSystemQuad
首先先看下ParticleSystemQuad，ParticleSystemQuad继承于ParticleSystem，拥有后者的所有特性，并且增加了一些新的特性：（1）粒子大小支持浮点数
（2）支持缩放
（3）支持选择
（4）支持subrect
（5）支持批渲染
ParticleSystemQuad同时也是其他特效的父类，创建一个粒子系统的函数调用顺序为：
Create→initWithFile→initWithDictionary在initWithDictionary中对粒子数据和纹理进行了读取和解析（这部分有兴趣的可以直接看源码）。
2.如何优化？
参考initWithDictionary的函参static bool initWithDictionary(ValueMap& dictionary, const std::string& dirname);static ParticleSystemQuad * create(ValueMap& valueMap, SpriteFrame *frame);
bool initWithValueMap(ValueMap &valueMap, SpriteFrame* frame);ParticleSystemQuad * ParticleSystemQuad::create( ValueMap& map, SpriteFrame *frame)
{
ParticleSystemQuad *ret = new ParticleSystemQuad();
if (ret && ret->initWithValueMap(map, frame))
{
ret->autorelease();
return ret;
}
CC_SAFE_DELETE(ret);
return ret;
}bool ParticleSystemQuad::initWithValueMap(ValueMap &valueMap, SpriteFrame* frame)
{
std::string dirname = "";
bool ret = false;
unsigned char *buffer = nullptr;
unsigned char *deflated = nullptr;
do
{
int maxParticles = valueMap["maxParticles"].asInt();
// self, not super
if(this->initWithTotalParticles(maxParticles))
{
// Emitter name in particle designer 2.0
_configName = valueMap["configName"].asString();
// angle
_angle = valueMap["angle"].asFloat();
_angleVar = valueMap["angleVariance"].asFloat();
// duration
_duration = valueMap["duration"].asFloat();
// blend function
if (_configName.length()>0)
{
_blendFunc.src = valueMap["blendFuncSource"].asFloat();
}
else
{
_blendFunc.src = valueMap["blendFuncSource"].asInt();
}
_blendFunc.dst = valueMap["blendFuncDestination"].asInt();
// color
_startColor.r = valueMap["startColorRed"].asFloat();
_startColor.g = valueMap["startColorGreen"].asFloat();
_startColor.b = valueMap["startColorBlue"].asFloat();
_startColor.a = valueMap["startColorAlpha"].asFloat();
_startColorVar.r = valueMap["startColorVarianceRed"].asFloat();
_startColorVar.g = valueMap["startColorVarianceGreen"].asFloat();
_startColorVar.b = valueMap["startColorVarianceBlue"].asFloat();
_startColorVar.a = valueMap["startColorVarianceAlpha"].asFloat();
_endColor.r = valueMap["finishColorRed"].asFloat();
_endColor.g = valueMap["finishColorGreen"].asFloat();
_endColor.b = valueMap["finishColorBlue"].asFloat();
_endColor.a = valueMap["finishColorAlpha"].asFloat();
_endColorVar.r = valueMap["finishColorVarianceRed"].asFloat();
_endColorVar.g = valueMap["finishColorVarianceGreen"].asFloat();
_endColorVar.b = valueMap["finishColorVarianceBlue"].asFloat();
_endColorVar.a = valueMap["finishColorVarianceAlpha"].asFloat();
// particle size
_startSize = valueMap["startParticleSize"].asFloat();
_startSizeVar = valueMap["startParticleSizeVariance"].asFloat();
_endSize = valueMap["finishParticleSize"].asFloat();
_endSizeVar = valueMap["finishParticleSizeVariance"].asFloat();
// position
float x = valueMap["sourcePositionx"].asFloat();
float y = valueMap["sourcePositiony"].asFloat();
this->setPosition( Point(x,y) );
_posVar.x = valueMap["sourcePositionVariancex"].asFloat();
_posVar.y = valueMap["sourcePositionVariancey"].asFloat();
// Spinning
_startSpin = valueMap["rotationStart"].asFloat();
_startSpinVar = valueMap["rotationStartVariance"].asFloat();
_endSpin= valueMap["rotationEnd"].asFloat();
_endSpinVar= valueMap["rotationEndVariance"].asFloat();
_emitterMode = (Mode) valueMap["emitterType"].asInt();
// Mode A: Gravity + tangential accel + radial accel
if (_emitterMode == Mode::GRAVITY)
{
// gravity
modeA.gravity.x = valueMap["gravityx"].asFloat();
modeA.gravity.y = valueMap["gravityy"].asFloat();
// speed
modeA.speed = valueMap["speed"].asFloat();
modeA.speedVar = valueMap["speedVariance"].asFloat();
// radial acceleration
modeA.radialAccel = valueMap["radialAcceleration"].asFloat();
modeA.radialAccelVar = valueMap["radialAccelVariance"].asFloat();
// tangential acceleration
modeA.tangentialAccel = valueMap["tangentialAcceleration"].asFloat();
modeA.tangentialAccelVar = valueMap["tangentialAccelVariance"].asFloat();
// rotation is dir
modeA.rotationIsDir = valueMap["rotationIsDir"].asBool();
}
// or Mode B: radius movement
else if (_emitterMode == Mode::RADIUS)
{
if (_configName.length()>0)
{
modeB.startRadius = valueMap["maxRadius"].asInt();
}
else
{
modeB.startRadius = valueMap["maxRadius"].asFloat();
}
modeB.startRadiusVar = valueMap["maxRadiusVariance"].asFloat();
if (_configName.length()>0)
{
modeB.endRadius = valueMap["minRadius"].asInt();
}
else
{
modeB.endRadius = valueMap["minRadius"].asFloat();
}
modeB.endRadiusVar = 0.0f;
if (_configName.length()>0)
{
modeB.rotatePerSecond = valueMap["rotatePerSecond"].asInt();
}
else
{
modeB.rotatePerSecond = valueMap["rotatePerSecond"].asFloat();
}
modeB.rotatePerSecondVar = valueMap["rotatePerSecondVariance"].asFloat();
} else {
CCASSERT( false, "Invalid emitterType in config file");
CC_BREAK_IF(true);
}
// life span
_life = valueMap["particleLifespan"].asFloat();
_lifeVar = valueMap["particleLifespanVariance"].asFloat();
// emission Rate
_emissionRate = _totalParticles / _life;
//don't get the internal texture if a batchNode is used
if (!_batchNode)
{
// Set a compatible default for the alpha transfer
_opacityModifyRGB = false;
if (!_configName.empty())
{
_yCoordFlipped = valueMap["yCoordFlipped"].asInt();
}
}
setDisplayFrame(frame);
ret = true;
}
} while (0);
free(buffer);
free(deflated);
return ret;
}粒子属性的获取：
ValueMap FileUtilsApple::getValueMapFromFile(const std::string& filename);SpriteFrame* create(const std::string& filename, const Rect& rect);3.如何使用？
auto plistData = FileUtils::getInstance()->getValueMapFromFile("Particles/emissionPart.plist");
auto emission_frame = SpriteFrame::create("Images/engine.jpg", Rect(0,0,25,32));
auto emitter = ParticleSystemQuad::create(plistData, emission_frame);
_background->addChild(_emitter, 10);4.源码下载
我也不知道3.0release会不会集成这个功能，这里先发出pull request的链接：https://github.com/cocos2d/cocos2d-x/pull/5979/files