Size visibleSize = Director::getInstance()->getVisibleSize();
Vec2 origin = Director::getInstance()->getVisibleOrigin();
RenderTexture *rt = RenderTexture::create(visibleSize.width,visibleSize.height);
rt->beginWithClear(1, 1, 0,1);
///1
this->setShaderProgram(ShaderCache::getInstance()->getGLProgram(GLProgram::SHADER_NAME_POSITION_COLOR));
CC_NODE_DRAW_SETUP();
CCPoint vertices;
ccColor4F colors;
int nVertices = 0;
vertices = CCPointMake(0, 0);
colors = ccc4f(1, 0, 0, 1);
vertices = CCPointMake(100, 0);
colors = ccc4f(0, 1, 0, 1);
vertices = CCPointMake(0, 100);
colors = ccc4f(0, 0, 1, 1);
vertices = CCPointMake(100, 100);
colors = ccc4f(1, 0, 0, 1);
ccGLEnableVertexAttribs(kCCVertexAttribFlag_Position | kCCVertexAttribFlag_Color);
glVertexAttribPointer(kCCVertexAttrib_Position, 2, GL_FLOAT, GL_FALSE, 0, vertices);
glVertexAttribPointer(kCCVertexAttrib_Color, 4, GL_FLOAT, GL_FALSE, 0, colors);
glBlendFunc(CC_BLEND_SRC, CC_BLEND_DST);
glDrawArrays(GL_TRIANGLE_STRIP, 0, (GLsizei)nVertices);
////1
rt->end();
rt->retain();
auto sprt = Sprite::createWithTexture(rt->getSprite()->getTexture());
sprt->setPosition(visibleSize.width / 2, visibleSize.height / 2);
addChild(sprt);
代码如上，问题：1.在注释1中间的代码为什么没有显示？ 2.rt->retain()为什么要加，不加也就没显示