com.jme.app
Class FixedFramerateGame

java.lang.Object
  extended by com.jme.app.AbstractGame
      extended by com.jme.app.FixedFramerateGame

public abstract class FixedFramerateGame
extends AbstractGame

A game that attempts to run at a fixed frame rate.

The main loop makes every effort to render at the specified rate, however this is not guaranteed and the frame rate may dip below the desired value. The game logic is updated at the same rate as the rendering; for example, if the rendering is running at 60 frames per second, the logic will also be updated 60 times per second.

Limiting the frame rate of the game is useful for playing nice with the underlying operating system. That is, if the game loop is left unchecked, it tends to use up 100% of the CPU cycles; while this may be fine for fullscreen applications (as it will yield to important processes) it can cause issues with applications running in a normal window.

If no frame rate is specified, the game will run at 60 frames per second.

Note that setFrameRate(int) cannot be called prior to calling start() or a NullPointerException will be thrown.

Version:
$Revision: 4131 $, $Date: 2009-03-19 20:15:28 +0000 (Thu, 19 Mar 2009) $
Author:
Eric Woroshow

Nested Class Summary
 
Nested classes/interfaces inherited from class com.jme.app.AbstractGame
AbstractGame.ConfigShowMode
 
Field Summary
 
Fields inherited from class com.jme.app.AbstractGame
display, finished, settings
 
Constructor Summary
FixedFramerateGame()
           
 
Method Summary
protected abstract  void cleanup()
          Called once the game loop has finished.
 float getFramesPerSecond()
          Gets the current frame rate.
protected abstract  void initGame()
          Create and initialise all game data.
protected abstract  void initSystem()
          Initialise the display system.
protected  void quit()
          Quits the program abruptly using System.exit.
protected abstract  void reinit()
          Rebuild the system.
protected abstract  void render(float interpolation)
          Display the updated game information.
 void setFrameRate(int fps)
          Set preferred frame rate.
 void start()
          Render and update logic at a specified fixed rate.
protected abstract  void update(float interpolation)
          Update the game state.
 
Methods inherited from class com.jme.app.AbstractGame
assertDisplayCreated, finish, getAttributes, getNewSettings, getVersion, setConfigShowMode, setConfigShowMode
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

FixedFramerateGame

public FixedFramerateGame()
Method Detail

setFrameRate

public void setFrameRate(int fps)
Set preferred frame rate. The main loop will make every attempt to maintain the given frame rate. This should not be called prior to the application being start() -ed.

Parameters:
fps - the desired frame rate in frames per second

getFramesPerSecond

public float getFramesPerSecond()
Gets the current frame rate.

Returns:
the current number of frames rendering per second

start

public final void start()
Render and update logic at a specified fixed rate.

Specified by:
start in class AbstractGame

quit

protected void quit()
Quits the program abruptly using System.exit.

Specified by:
quit in class AbstractGame
See Also:
AbstractGame.quit()

update

protected abstract void update(float interpolation)
Description copied from class: AbstractGame
Update the game state.

Any user input checks, changes to game physics, AI, networking, score table updates, and so on, should happen in this method. The rate at which this method is called will depend on the specific game implementation in use.

Note that this method should not update the screen.

Specified by:
update in class AbstractGame
Parameters:
interpolation - unused in this implementation
See Also:
AbstractGame.update(float interpolation)

render

protected abstract void render(float interpolation)
Description copied from class: AbstractGame
Display the updated game information.

This method normally involves clearing the display and rendering the scene graph, although subclasses are free to do any screen related work here. The rate at which this method is called will depend on the specific game implementation in use.

Note that this method is run on the OpenGL thread, it should not alter the game state in any way.

Specified by:
render in class AbstractGame
Parameters:
interpolation - unused in this implementation
See Also:
AbstractGame.render(float interpolation)

initSystem

protected abstract void initSystem()
Description copied from class: AbstractGame
Initialise the display system.

This includes not just the DisplaySystem but also any other input and display related elements such as windows, cameras, and the input system.

Note that the display must be initialised in this method.

Specified by:
initSystem in class AbstractGame
See Also:
AbstractGame.initSystem()

initGame

protected abstract void initGame()
Description copied from class: AbstractGame
Create and initialise all game data.

What happens here is purely application dependent; it is where, for example, the initial scene graph and the starting environment could be loaded. It is suggested that any frequently used resources are loaded and cached in this method.

This method is called once after AbstractGame.initSystem() has completed.

Specified by:
initGame in class AbstractGame
See Also:
AbstractGame.initGame()

reinit

protected abstract void reinit()
Description copied from class: AbstractGame
Rebuild the system.

This method is called when the system requires rebuilding, for example is the screen resolution is altered. This method may be called at any time by client code.

Specified by:
reinit in class AbstractGame
See Also:
AbstractGame.reinit()

cleanup

protected abstract void cleanup()
Description copied from class: AbstractGame
Called once the game loop has finished.

Subclasses should use this method to release any resources, for example data that was loaded in the initXXX() methods.

Specified by:
cleanup in class AbstractGame
See Also:
AbstractGame.cleanup()