<< Chapter < Page
  Xna game studio     Page 13 / 16
Chapter >> Page >
"Called when the game determines it is time to draw a frame. Override this method with game-specific rendering code.

Note that significant changes were made to the required contents of the Game.Draw method in XNA 4.0 as compared to XNA 3.1.

Game loop timing

As you learned earlier, Update and Draw are called at different rates depending on whether IsFixedTimeStep is true or false.

If IsFixedTimeStep is false, Update and Draw will be called sequentially as often as possible.

If IsFixedTimeStep is true, Update will be called at the interval specified in TargetElapsedTime , while Draw will continue to be called as often as possible. For more information on fixed-step and variable-step game loops, see Application Model Overview ."

Because this program doesn't override the Update method, it doesn't matter how often the Draw method is called. Each time it is drawn, the sprite is drawn in the same position as shown in Figure 3 and Figure 4 .

More general information

What is a sprite?

According to the 2D Graphics Overview ,

"Sprites are 2D bitmaps drawn directly on the screen, as opposed to being drawn in 3D space. Sprites are commonly used to display information such ashealth bars, number of lives, or text such as scores. Some games, especially older games, are composed entirely of sprites."

What is a bitmap?

According to the documentation for the Bitmap class,

"A bitmap consists of the pixel data for a graphics image and its attributes. There are many standard formats for saving a bitmap to a file. GDI+ supports thefollowing file formats: BMP, GIF, EXIG, JPG, PNG and TIFF."

What is GDI+?

According to the documentation ,

"Microsoft Windows GDI+ is a class-based API for C/C++ programmers. It enables applications to use graphics and formatted text on both the videodisplay and the printer. Applications based on the Microsoft Win32 API do not access graphics hardware directly. Instead, GDI+ interacts with device driverson behalf of applications."

What about our image?

Working backwards through the above information, we started with an image file named gorightarrow.png . We manually added the file to the Content folder producing a game asset with an Asset Name of gorightarrow (see Figure 7 ).

Then we called the Load method in Listing 6 to load the contents of the file into an object of type Texture2D and saved that object's reference in the instance variable named myTexture . At that point in the process, we had converted the contents of our image fileinto a format that can be thought of as a sprite. The variable named myTexture contains a reference to our sprite.

Beginning of the Game.Draw method

The Game.Draw method begins in Listing 7 . I am referring to the method here as Game.Draw to distinguish it from the method named SpriteBatch.Draw , which we will encounter shortly.

Listing 7 . Beginning of the Game.Draw method.

protected override void Draw(GameTime gameTime) { GraphicsDevice.Clear(Color.CornflowerBlue);

GameTime information

Each time the Game.Draw method is executed, the incoming parameter contains time information encapsulated in an object of type GameTime . According to the documentation, the GameTime object provides a

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
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
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.
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
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get the best Algebra and trigonometry course in your pocket!

Source:  OpenStax, Xna game studio. OpenStax CNX. Feb 28, 2014 Download for free at https://legacy.cnx.org/content/col11634/1.6
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Xna game studio' conversation and receive update notifications?