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Learn how to develop a Sprite class from which you can instantiate and animate swarms of sprite objects.

Table of contents

Preface

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.

The purpose of this module is to teach you how to develop a sprite class (see Sprite01 ) from which you can instantiate and animate swarms of sprite objects.

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 imagesand listings while you are reading about them.

Figures

  • Figure 1 . Graphic output from program named Slick0200.
  • Figure 2 . Graphic output from the earlier program.

Listings

  • Listing 1 . Beginning of the class named Sprite01.
  • Listing 2 . Beginning of the class named Slick0200.
  • Listing 3 . Beginning of the init method.
  • Listing 4 . Populate the array.
  • Listing 5 . The update method.
  • Listing 6 . The move method of the Sprite01 class.
  • Listing 7 . The edgeBounce method of the Sprite01 class.
  • Listing 8 . The render method.
  • Listing 9 . The draw method of the Sprite01 class.
  • Listing 10 . Source code for the program named Slick0200.
  • Listing 11 . Source code for the sprite class named Sprite01.

Preview

I will present and explain a program that uses a class named Sprite01 (see Listing 11 ) to produce an animation of 1000 ladybug sprite objects flying around inside thegame window as shown in Figure 1 .

Figure 1 . Graphic output from program named Slick0200.
Missing image.

The frame rate

As you can see from the text in the upper-left corner of Figure 1 , the program is running at 62 frames per second. My rather old desktop computer can maintain this frame rate up to about 7000 sprite objects.Beyond that, it can no longer handle the computing load and the frame rate begins to decrease.

What you have learned

In the previous module, you learned how to use objects of the SpriteSheet class and the Animation class to perform relatively complex sprite sheet animations.

What you will learn

In this module, you will learn how to develop a sprite class from which you can instantiate and animate swarms of sprite objects. In the next two modules,you will learn how to put that class to work.

General background information

While the Slick2D library provides many useful classes, there is nothing to stop you from developing your own classes to work in combination with theSlick2D library classes. That is the thrust of this module.

In an earlier module titled Slick0150: A first look at sprite motion, collision detection, and timing control , you learned how to cause a single sprite to bounce around inside the game window as shown in Figure 2 .

Questions & Answers

What is demand
TECK Reply
the amount of a good that buyers are willing and able to purchase
Asit
what is population
Amadou Reply
The people living within a political or geographical boundary.
Ziyodilla
what happens to price and quantity when demand curves shift to the right
Asha Reply
price level goes up. quantity demand increases
Asit
example- inferior goods
Asit
demand law
Athony
Its states that higher the price the of the commodity, and lower the quantity demanded
Kosiso
I am confused but quantity demand will increase.
Asit
No. That's the law of supply
Kosiso
what happens to price and quantity when supply curve shifts left?
Asha Reply
price level will increase
Asit
quantity demand will decrease
Asit
what is inflation
Pop Reply
inflation is a general and ongoing rise in the level of prices in an entire economy.
cynthia
is the pasistance increase in the price of a country economy
Liyu
kk
Duppy
yes
Aadi
how does inflation affects the economy of a country? what is deflation?
Augustine
deflation can simply be define as the persistence decrease in price of a countrys economy
Liyu
the revenge of malthus relates "revenge" with "commodity prices". collect data for 3 commodoties and check their price evolution
Jamshi Reply
what is elasticity
dubela Reply
Elasticity is an economics concept that measures responsiveness of one variable to changes in another variable.
cynthia
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Augustine
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cynthia
Computer software represents
Mboledi Reply
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plz Reply
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Kenyana
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MUBARAK
like a banana
Ahmed
demand is the process whereby consumers are willing and able to purchase a particular product at various price over a given period of time
Samuel Reply
The law of dinimish
Frank Reply
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Frank
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Frank
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Frank
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jackie Reply
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King
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Asheeru Reply
what is demand
Levinel Reply
Demand is an economic principle referring to a consumer's desire to purchase goods and services and willingness to pay a price for a specific good or service.
Ali
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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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