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How to create a game

I will begin with a simplified explanation of how to create games using XNA.

Game1 extends Game

To begin with, note that the Game1 class extends the Game class. We do not modify the Game class. Instead, we modify the behavior of the Game class by extending it and overriding some of its methods.

Main method calls the Run method

As you saw earlier in Listing 2 , the Main method in the file named Program.cs instantiates an object of the Game1 class (shown in Listing 3 ) and calls the Run method on that object. That starts the program running.

The Run method

The class named Game1 does not define and does not override a method named Run . However, it does inherit a method named Run from the Game class.

Therefore, when the Run method is called on the object of the Game1 class, the version of the Run method that is defined in the superclass named Game is executed.

Override five methods

The skeleton code for the Game1 class in Listing 3 overrides the following five methods inherited from the Game class:

  1. Initialize
  2. LoadContent
  3. UnloadContent
  4. Update
  5. Draw

Initialization

The first three methods contain code that is needed to get everything initialized at the start of the game play and to shut down the program at theend of the game play.

The game loop

Once the game is initialized, the Run method, or some method called by the Run method ping-pongs back and forth between calls to the overridden Update method and the overridden Draw method. (Note, however that the two methods don't necessarily take turns executing.)

Override Update for game logic

You override the Update method to create the program logic associated with game play. To accomplish this, you will likely need to defineother methods, define other classes, instantiate objects of other classes, call methods on those objects, testthe keyboard, test the mouse, etc. In other words, at this point you need to know how to program in C# .

Override the Draw method

You override the Draw method to cause the various graphics objects in your game to be rendered in the game window shown in Figure 1 .

This module includes an explanation of a very simple program that displays a green arrow sprite near the upper-left corner of the game window (see Figure 3 ).

Preview

I will create a simple Windows game application that imports the image shown in Figure 2 . Note that this is a rectangular image with an (almost) transparent background. (The values of the alpha bytes outside the blueelliptical shape are about 5.)

Figure 2 . Raw image with an (almost) transparent background.

Missing image

If you would like to replicate my program using this image, you should be able to right-click on the image in Figure 2 , download it, and save it on your computer. You can save it under any name you choose but the file name extensionshould be png .

Program output

The program displays the image near the upper-left corner of the game window and honors the transparency of the background as shown in Figure 3 .

Figure 3 . Cropped upper-left corner of the game window.

Missing image

What if you don't honor the transparent background?

Figure 4 shows the result of causing the alpha transparency value to be ignored and allowing the pixels that are almosttransparent in Figure 3 to be opaque.

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
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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