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General background information

The three pillars of OOP

An object-oriented programming language like C# supports encapsulation , inheritance , and polymorphism . In this module, you will learn how to take advantage of encapsulation.

Wanted, lots of sprites

Assume that you are writing a game program in which you need to have several dozen similar sprites on the screen at the same time. Creating and controllingthat many sprites without using encapsulation would require you to write a lot of program code.

Encapsulation to the rescue

However, by encapsulating the characteristics of a sprite into a class, which is a blueprint for an object, you can instantiate sprite objects just like cutting out cookies with a cookie cutter.

In this module, you will learn to define and use a very simple Sprite class. In future modules, you will learn how to modify the Sprite class to make it more sophisticated by making use of inheritance andpolymorphism in addition to encapsulation


The XNA project that I will explain in this module is named XNA0126Proj . This project demonstrates how to design and use a very simple version of a Sprite class. An object instantiated from the Sprite class has the following general characteristics:

  • It can be instantiated without an image.
  • It can be instantiated with an image.
  • It can have its image set.
  • It can have its position within the game window set.
  • It can cause itself to be drawn.

Demonstrate how to use the Sprite class

Methods are overridden in the standard XNA Game1 class that demonstrate the use of the Sprite class.

One Sprite object is instantiated in the overridden LoadContent method of the Game1 class. The object's reference is saved in a generic List object. Twenty-three more Sprite objects are instantiated in the overridden Update method while the game loop is running.

Instantiate Sprite objects on the move

A new Sprite object is instantiated in the Update method every 8th iteration of the game loop until twenty-four Sprite objects have been instantiated. The object's references are saved in the samegeneric List object mentioned above.

An image of a blue ball is stored in 12 of the objects and an image of a red ball is stored in the other 12 objects. The red and blue balls alternate and the Sprite objects are drawn in a diagonal line as shown in Figure 1 .

Figure 1 . Seven Sprite objects.

missing image

Seven Sprite objects

Figure 1 shows the game window after seven of the twenty-four Sprite objects have been instantiated and drawn in the game window.

Move to the right and down

The line of Sprite objects moves across the game window from upper left to lower right as the Sprite objects are being instantiated. They stop moving when they reach the bottom right corner of thegame window.

When the objects stop moving, the image in the topmost Sprite object is changed from a blue ball to a green ball as shown in Figure 2 .

Figure 2 . Twenty-four Sprite objects with a green one at the top.

missing image

Discussion and sample code

As usual, I will explain the program code in fragments. A complete listing of the class named Sprite is provided in Listing 14 and a complete listing of the class named Game1 is provided in Listing 15 .

Questions & Answers

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.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
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
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
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Source:  OpenStax, Xna game studio. OpenStax CNX. Feb 28, 2014 Download for free at https://legacy.cnx.org/content/col11634/1.6
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