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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

can someone help me with some logarithmic and exponential equations.
Jeffrey Reply
sure. what is your question?
okay, so you have 6 raised to the power of 2. what is that part of your answer
I don't understand what the A with approx sign and the boxed x mean
it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
I'm not sure why it wrote it the other way
I got X =-6
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x-6
oops. ignore that.
so you not have an equal sign anywhere in the original equation?
Commplementary angles
Idrissa Reply
im all ears I need to learn
right! what he said ⤴⤴⤴
what is a good calculator for all algebra; would a Casio fx 260 work with all algebra equations? please name the cheapest, thanks.
Kevin Reply
a perfect square v²+2v+_
Dearan Reply
kkk nice
Abdirahman Reply
algebra 2 Inequalities:If equation 2 = 0 it is an open set?
Kim Reply
or infinite solutions?
The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
Embra Reply
if |A| not equal to 0 and order of A is n prove that adj (adj A = |A|
Nancy Reply
rolling four fair dice and getting an even number an all four dice
ramon Reply
Kristine 2*2*2=8
Bridget Reply
Differences Between Laspeyres and Paasche Indices
Emedobi Reply
No. 7x -4y is simplified from 4x + (3y + 3x) -7y
Mary Reply
is it 3×y ?
Joan Reply
J, combine like terms 7x-4y
Bridget Reply
im not good at math so would this help me
Rachael Reply
I'm not good at math so would you help me
what is the problem that i will help you to self with?
how do you translate this in Algebraic Expressions
linda Reply
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
Chris 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?
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
bamidele Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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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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