【玩轉cocos2d-x之三十七】粒子系統的載入優化
阿新 • • 發佈：2019-01-11
Cocos2d-x的粒子系統是通過載入plist生成的。plist包含兩部分內容：粒子系統屬性和粒子紋理。然而每次呼叫create都會對plist進行讀取解析，如果重複地使用同一個粒子效果，這樣的呼叫明顯是低效冗餘的。所以我們要做的是，將粒子系統屬性和粒子紋理分別抽出。
（1）將粒子系統屬性預載入並全域性儲存，避免每次進行讀取。
（2）粒子紋理可視且可以進行紋理打包，載入粒子紋理就和載入普通的圖片一樣。
本文通過增加ParticleSystemQuad的介面實現對粒子系統屬性和紋理幀的直接載入，來提高粒子系統的載入效率和實現記憶體紋理的優化。
1.ParticleSystemQuad
首先先看下ParticleSystemQuad，ParticleSystemQuad繼承於ParticleSystem，擁有後者的所有特性，並且增加了一些新的特性：（1）粒子大小支援浮點數
（2）支援縮放
（3）支援選擇
（4）支援subrect
（5）支援批渲染
ParticleSystemQuad同時也是其他特效的父類，建立一個粒子系統的函式呼叫順序為：
Create→initWithFile→initWithDictionary
在initWithDictionary中對粒子資料和紋理進行了讀取和解析（這部分有興趣的可以直接看原始碼）。
2.如何優化？
參考initWithDictionary的函參static bool initWithDictionary(ValueMap& dictionary, const std::string& dirname);原始碼如下：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;
}粒子屬性的獲取：
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);