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Learn how a game program written with the Slick game library creates and maintains a game loop.

Table of contents


This module is one in a collection of modules designed to teach you about the anatomy of a game engine.

Although the modules in this collection will concentrate on the Java game library named Slick2D, theconcepts involved and the knowledge that you will gain is applicable to different game engines written in different programming languages as well.

Viewing tip

I recommend that you open another copy of this module in a separate browser window and use the following links to easily find and view the Figuresand Listings while you are reading about them.


  • Figure 1 . Screen output from program named Slick0130a.


  • Listing 1 . The start method of the AppGameContainer class.
  • Listing 2 . The gameLoop method of the AppGameContainer class.
  • Listing 3 . Beginning of the updateAndRender method of the GameContainer class.
  • Listing 4 . The remainder of the updateAndRender method of the GameContainer class.
  • Listing 5 . Beginning of the class named Slick0130a.
  • Listing 6 . The main method.
  • Listing 7 . The overridden init method.
  • Listing 8 . The overridden update method.
  • Listing 9 . The overridden render method.
  • Listing 10 . Source code for the program named Slick0130a.


What you have learned

The main purpose of this and the previous module is to analyze the behavior of the Slick2D game engine when you call the start method to cause a Slick2D game program to start running.

In the previous module, you learned how and why you should extend the BasicGame class instead of implementing the Game interface directly.

You learned about the behavior of the constructors for the AppGameContainer class.

You learned that the start method of the AppGameContainer class (see Listing 1 ) calls the following three methods:

  • setup
  • getDelta
  • gameLoop

You learned about the behavior of the setup and getDelta methods.

What you will learn

I will explain the overall behavior of the gameLoop method in this module.

In addition, you will learn

  • about a property of the GameContainer class named running , and how it is used by the start method to keep the game loop running,
  • about the salient features of the gameLoop method of the AppGameContainer class,
  • about the updateAndRender method of the GameContainer class and how it decides when and if to call the update and render methods of the object of the Game class that is wrapped in the container,
  • about the difference between normal delta and smoothed delta,
  • about minimumLogicInterval and maximumLogicInterval and how the contents of those two variables are used to determine if, when, and how many times to call the update method during each iteration of the game loop,
  • how the contents of minimumLogicInterval and maximumLogicInterval are used to determine the value that is passed as delta each time the update method is called,
  • that the render method is normally called once and only once during each iteration of the game loop,
  • how you can use the value of delta that is received by the update method to control the behavior of a game program,
  • that you can set the size of the game window when you instantiate an object of the AppGameContainer class by passing dimension parameters to the constructor,
  • that you can set the target frame rate by calling the setTargetFrameRate method on the GameContainer object, and
  • how to display text in the game window.

Questions & Answers

How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
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Stoney Reply
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Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
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Damian Reply
absolutely yes
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Akash Reply
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s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
how can I make nanorobot?
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Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
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Smarajit Reply
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Source:  OpenStax, Anatomy of a game engine. OpenStax CNX. Feb 07, 2013 Download for free at https://legacy.cnx.org/content/col11489/1.13
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