代码是参考ray wenderlish的一个教程，每点击一次鼠标创建一次rendertexture，
在rendertexture对象里面添加了customcommand
然后我在customcommand对应的render()函数里面添加了opengl代码，并在其最后添加glBlendFunc(GL_ZERO, GL_ZERO);
最后的结果就是，第一次rendertexture的内容正确显示，但第二次以后屏幕全黑
#include "HelloWorldScene.h"
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;
}
bool HelloWorld::init()
{
if ( !Layer::init() )
{
return false;
}
_screenSize = Director::getInstance()->getVisibleSize();
Point origin = Director::getInstance()->getVisibleOrigin();
auto listener = EventListenerTouchOneByOne::create();
listener->onTouchBegan = CC_CALLBACK_2(HelloWorld::onTouchBegan, this);
_eventDispatcher->addEventListenerWithSceneGraphPriority(listener, this);
this->schedule(schedule_selector(HelloWorld::step));
return true;
}
Sprite* HelloWorld::initSpriteWithColor(Color4F c1, Color4F c2, float textureWidth, float textureHeight, int nStripes)
{
_c2 = c2;
_nStripes = nStripes;
auto rt = RenderTexture::create(textureWidth, textureHeight);
rt->beginWithClear(c1.r, c1.g, c1.b, c1.a);
auto render = Director::getInstance()->getRenderer();
_customCommand.init(rt->getGlobalZOrder());
_customCommand.func = CC_CALLBACK_0(HelloWorld::render, this);
render->addCommand(&_customCommand);
rt->end();
auto sprite = Sprite::createWithTexture(rt->getSprite()->getTexture());
return sprite;
}
Color4F HelloWorld::randomBrightColor()
{
while(true)
{
float requiredBrightness = 192;
Color4B randomColor =
Color4B(std::rand() % 255, std::rand() % 255, std::rand() % 255, 255);
if(randomColor.r > requiredBrightness ||
randomColor.g > requiredBrightness ||
randomColor.b > requiredBrightness)
{
return Color4F(randomColor);
}
}
}
void HelloWorld::genBackGround()
{
srand(time(NULL));
auto bgColor = this->randomBrightColor();
auto color2 = this->randomBrightColor();
int nSprites = ((rand() % 4) + 1) * 2;
_backGround = this->initSpriteWithColor(bgColor, color2, _screenSize.width , _screenSize.height, nSprites);
_backGround->setPosition(Point(_screenSize.width / 2, _screenSize.height / 2));
_backGround->setScale(0.5);
this->addChild(_backGround, -1);
}
void HelloWorld::onEnter()
{
log("entered");
Node::onEnter();
this->genBackGround();
}
bool HelloWorld::onTouchBegan(Touch *touch, Event *unused_event)
{
log("touched");
_backGround->removeFromParentAndCleanup(true);
this->genBackGround();
return true;
}
void HelloWorld::step(float dt)
{
}
void HelloWorld::render()
{
log("HelloWorld::render()");
float textureWidth = _screenSize.width;
float textureHeight = _screenSize.height;
this->setShaderProgram(ShaderCache::getInstance()->getProgram(GLProgram::SHADER_NAME_POSITION_COLOR));
CC_NODE_DRAW_SETUP();
Point* vertices = new Point;
Color4F* colors = new Color4F;
int nVertices = 0;
float x1 = -textureWidth;
float x2;
float y1 = textureWidth;
float y2 = 0;
float dx = textureWidth / _nStripes * 2;
float stripeWidth = dx / 2;
for(int i = 0; i < _nStripes; i++)//changed _nStripes
{
x2 = x1 + textureWidth;
vertices = Point(x1, y1);
colors = Color4F(_c2.r, _c2.g, _c2.b, _c2.a);
vertices = Point(x1 + stripeWidth, y1);
colors = Color4F(_c2.r, _c2.g, _c2.b, _c2.a);
vertices = Point(x2, y2);
colors = Color4F(_c2.r, _c2.g, _c2.b, _c2.a);
vertices = vertices;
colors = Color4F(_c2.r, _c2.g, _c2.b, _c2.a);
vertices = vertices;
colors = Color4F(_c2.r, _c2.g, _c2.b, _c2.a);
vertices = Point(x2 + stripeWidth, y2);
colors = Color4F(_c2.r, _c2.g, _c2.b, _c2.a);
x1 += dx;
}
GL::enableVertexAttribs( GL::VERTEX_ATTRIB_FLAG_POSITION | GL::VERTEX_ATTRIB_FLAG_COLOR);
glBlendFunc(CC_BLEND_SRC, CC_BLEND_DST);
glVertexAttribPointer(GLProgram::VERTEX_ATTRIB_POSITION, 2, GL_FLOAT, GL_FALSE, 0, vertices);
glVertexAttribPointer(GLProgram::VERTEX_ATTRIB_COLOR, 4, GL_FLOAT, GL_TRUE, 0, colors);
glDrawArrays(GL_TRIANGLES, 0, (GLsizei)nVertices);
float gradientAlpha = 0.5f;
nVertices = 0;
vertices = Point(0, 0);
colors = Color4F(0.0, 0.0, 1.0, gradientAlpha);
vertices = Point (textureWidth - 300, 0);
colors = Color4F(0.0, 0.0, 1.0, gradientAlpha);
vertices = Point (0, textureHeight - 300);
colors = Color4F(0.0, 0.0, 1.0, gradientAlpha);
vertices = Point (textureWidth - 300, textureHeight - 300);
colors = Color4F(0.0, 0.0, 1.0, gradientAlpha);
glVertexAttribPointer(GLProgram::VERTEX_ATTRIB_POSITION, 2, GL_FLOAT, GL_FALSE, 0, vertices);
glVertexAttribPointer(GLProgram::VERTEX_ATTRIB_COLOR, 4, GL_FLOAT, GL_TRUE, 0, colors);
glDrawArrays(GL_TRIANGLE_STRIP, 0, (GLsizei)nVertices);
float boardHeight = textureHeight / 16;
float boardAlpha = 1.0f;
nVertices = 0;
vertices = Point(0, 0);
colors = Color4F(1.0f, 0.0f, 1.0f, boardAlpha);
vertices = Point(textureWidth, 0);
colors = Color4F(1.0f, 0.0f, 1.0f, boardAlpha);
vertices = Point(0, boardHeight);
colors = Color4F(1.0f, 0.0f, 1.0f, boardAlpha);
vertices = Point(textureWidth, boardHeight);
colors = Color4F(1.0f, 0.0f, 1.0f, boardAlpha);
glVertexAttribPointer(GLProgram::VERTEX_ATTRIB_POSITION, 2, GL_FLOAT, GL_FALSE, 0, vertices);
glVertexAttribPointer(GLProgram::VERTEX_ATTRIB_COLOR, 4, GL_FLOAT, GL_TRUE, 0, colors);
glDrawArrays(GL_TRIANGLE_STRIP, 0, (GLsizei)nVertices);
glBlendFunc(GL_ZERO, GL_ZERO); /////添加了这句并点击后出现问题
}
```
要知道cocos2d的render顺序，应该必须要看底层，我尝试去看了以下cocos2dx的底层实现，但看不懂，请教一下大家