cocos3——1.引擎运行流程

1.程序入口

    // create the application instance
    AppDelegate app;
    return Application::getInstance()->run();

2.主循环

int Application::run():

while(!glview->windowShouldClose())
    {
        QueryPerformanceCounter(&nNow);
        if (nNow.QuadPart - nLast.QuadPart > _animationInterval.QuadPart)
        {
            nLast.QuadPart = nNow.QuadPart;

			// 导演的主循环
            director->mainLoop();
            glview->pollEvents();
        }
        else
        {
            Sleep(0);
        }
    }

mainLoop->drawScene:

    pushMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW);

    if (_runningScene)
    {
        //clear draw stats
        _renderer->clearDrawStats();

		// visit和draw场景（但draw只是添加渲染命令）
		// 进行渲染命令是在：renderer->render();
        //render the scene
        _runningScene->render(_renderer);

        _eventDispatcher->dispatchEvent(_eventAfterVisit);
    }

	// 通知节点，独立于场景之后渲染
    // draw the notifications node
    if (_notificationNode)
    {
        _notificationNode->visit(_renderer, Mat4::IDENTITY, 0);
    }

    if (_displayStats)
    {
        showStats();
    }
	// 下面是渲染_notificationNode和stats
    _renderer->render();

    _eventDispatcher->dispatchEvent(_eventAfterDraw);

    popMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW);

    _totalFrames++;

    // swap buffers
    if (_openGLView)
    {
        _openGLView->swapBuffers();
    }

void Scene::render(Renderer* renderer)：

        Camera::_visitingCamera = defaultCamera;
        director->pushMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_PROJECTION);
        director->loadMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_PROJECTION, Camera::_visitingCamera->getViewProjectionMatrix());

        //visit the scene
        visit(renderer, Mat4::IDENTITY, 0);
        renderer->render();

        director->popMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_PROJECTION);

3.节点遍历

void Node::visit(Renderer* renderer, const Mat4 &parentTransform, uint32_t parentFlags)：

    // quick return if not visible. children won't be drawn.
    if (!_visible)
    {
        return;
    }

    uint32_t flags = processParentFlags(parentTransform, parentFlags);

    // IMPORTANT:
    // To ease the migration to v3.0, we still support the Mat4 stack,
    // but it is deprecated and your code should not rely on it
    Director* director = Director::getInstance();
    director->pushMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW);
    director->loadMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW, _modelViewTransform);

    bool visibleByCamera = isVisitableByVisitingCamera();

    int i = 0;

    if(!_children.empty())
    {
        sortAllChildren();
        // draw children zOrder < 0
        for( ; i < _children.size(); i++ )
        {
            auto node = _children.at(i);

            if ( node && node->_localZOrder < 0 )
                node->visit(renderer, _modelViewTransform, flags);
            else
                break;
        }
        // self draw
        if (visibleByCamera)
            this->draw(renderer, _modelViewTransform, flags);

        for(auto it=_children.cbegin()+i; it != _children.cend(); ++it)
            (*it)->visit(renderer, _modelViewTransform, flags);
    }
    else if (visibleByCamera)
    {
        this->draw(renderer, _modelViewTransform, flags);
    }

    director->popMatrix(MATRIX_STACK_TYPE::MATRIX_STACK_MODELVIEW);