= Manual =

== How to use Kernel/Task subsystem ==

Most of the games has got a main-loop. During the execution of one cycle of the loop a game engine has to perfrom a lot of tasks, e.g. checking user input, rendering, physic update and so on. [[BR]] 
nrEngine's Kernel/Task subsystems provides a simple but powerfull interface to manage the main loop. The engine does contains a '''Kernel''' which runs in the background of the engine. A '''Task''' can be bound to the kernel, so that it gets updated every cycle. A task can be any user derived class which has to perform repetitive jobs, e.g. check for user input or stream data from the disk. [[BR]]
Moreover a task can get a specific order number or it can depend on another task. Hence the engine does provide a simple graph based task execution system. The functionality of the nrEngine's kernel is similar to the operating system's one, but in a very simple form. [[BR]]
And finally a task can be shifted to a thread, so that it executes in parallel to the main application.

The following code show you how to use the engine's kernel subsystem for a simple managment of tasks in your application/game:
{{{
#!cpp
#include <nrEngine/nrEngine.h>

using namespace nrEngine;

//! This is a simpel task performing sound output
class SoundTask :  public ITask
{	
public: 
  
	SoundTask();
	~SoundTask();

        //! This method will be called when the task stops				
	Result stopTask();	
	
	//! Task was added to the kernel, so initilize it
	Result onAddTask();
	
	//! This is called every cycle, so that SoundTask can react on it
	Result updateTask();

        ...
};

void main()
{
        // Initialize engine
        ...


        // Add the sound task to the kernel with a low order number
        Engine::sKernel()->AddTask(new SoundTask(), ORDER_LOW);

        // Executes engine's kernel, hence execute all tasks which are in the kernel
        // The function returns if there are no more tasks in the kernel (i.e. if all tasks stops)
        Engine::sKernel()->Execute();
}
}}}  

See also: ["ManualPage"]