3 OSG创建渲染线程的过程
OSG创建渲染线程的过程
图形渲染线程是静态函数，为：
static unsigned int __stdcall StartThread(void *data)
它是在int Thread::start()中被调用：
int Thread::start()
{
pd->tid.set( (void*)_beginthreadex(NULL,pd->stackSize,ThreadPrivateActions::StartThread,static_cast<void *>(this),0,&ID));
。。。
}
int ViewerBase::run()
{
if (!isRealized())
{
realize();
}
if( ){
while (!done())
{
frame();
}
}
}
void Viewer::realize()
{
。。
setUpViewAcrossAllScreens();
setUpThreading();
}
void ViewerBase::setUpThreading()
{
。。
startThreading();
}
void ViewerBase::startThreading()
{
switch(_threadingModel):
case(DrawThreadPerContext)://此处被执行
osg::ref_ptr<osg::BarrierOperation> swapReadyBarrier = contexts.empty() ? 0 : new osg::BarrierOperation(contexts.size(), osg::BarrierOperation::NO_OPERATION);
osg::ref_ptr<osg::SwapBuffersOperation> swapOp = new osg::SwapBuffersOperation();
gc->createGraphicsThread();
gc->getGraphicsThread()->add(new osg::RunOperations());
gc->getGraphicsThread()->startThread();
}
----------
void GraphicsContext::createGraphicsThread()
{
if (!_graphicsThread)//初始时，_graphicsThread= false;
{
setGraphicsThread(new GraphicsThread);//此行被执行
}
}
void GraphicsContext::setGraphicsThread(GraphicsThread* gt)
{
_graphicsThread = gt;
。。。
_graphicsThread->setParent(this);
}
---------
int Thread::startThread()
{
if (_prvData) return start();
else return 0;
}
int Thread::start() { pd->tid.set( (void*)_beginthreadex(NULL,pd->stackSize,ThreadPrivateActions::StartThread,static_cast<void *>(this),0,&ID));
pd->threadStartedBlock.block();/*主线程阻塞，启动图形渲染线程，static unsigned int __stdcall StartThread(void *data)函数被调用，而且StartThread ()函数中执行到pd->threadStartedBlock.release();后，切换到主线程*/
}
----------
void ViewerBase::frame(double simulationTime)
{
advance(simulationTime);
eventTraversal();
updateTraversal();
renderingTraversals();
}
void ViewerBase::renderingTraversals()
{ 。。
for(Cameras::iterator camItr = cameras.begin();
camItr != cameras.end(); ++camItr)
{
if (renderer)
{
if (!renderer->getGraphicsThreadDoesCull() && !(camera->getCameraThread()))
{
renderer->cull();//会被执行
}
}
}
if (!((*itr)->getGraphicsThread()) && (*itr)->valid())//测试时，没有被调用
{ makeCurrent(*itr);//测试时，没有被调用
(*itr)->runOperations();//测试时，没有被调用
}
}