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  • Listing 1 . Beginning of the class named Game1.
  • Listing 2 . The constructor for the class named Game1.
  • Listing 3 . Beginning of the overridden LoadContent method.
  • Listing 4 . Compute the position of the UFO relative to the game window.
  • Listing 5 . Compute the base scale factor for the background image.
  • Listing 6 . Beginning of the overridden Update method.
  • Listing 7 . Apply dynamic scaling to the background image.
  • Listing 8 . Adjust the origin for the background image.
  • Listing 9 . Beginning of the overridden Game.Draw method.
  • Listing 10 . Draw the UFO.
  • Listing 11 . The class named Game1 for the project named XNA0124Proj.

General background information

Layer depth

When you draw two or more sprites using the SpriteBatch.Draw method, you can specify the z-order as the last ( layerDepth ) parameter to the Draw method. By default, a non-transparent sprite that is drawn with a layerDepth value of 0.0 will hide sprites drawn with greater layerDepth values. The greater the layerDepth value, the further back will be the sprite in the z-order, up to a maximum value of 1.0, which represents the extreme back of thez-order.

Color key transparency

During the design phase of project development, you can cause the program to interpret one specific color as being transparent by setting the Color Key Color property to that color and setting the Color Key Enabled property to true as shown in Figure 1 . Although I have never tried to do it, you can also apparently accomplish this at runtime by settingproperties of the TextureProcessor class.

Figure 1 . Property settings for green transparency.

missing image

Transparent green

Figure 1 shows the property settings required to cause every pixel having a color of pure green (0,255,0) to be replaced with transparent black, regardlessof the actual alpha value of the green pixel.

Store your image in a lossless image file

If you use this capability, you must be careful not to store your image in a file that uses lossy compression, such as a JPEG file. If you do, the pure colorthat went into the file is not likely to be pure when you later extract the image from the file. Instead, you should store your image in a lossless filesuch as a BMP file or a PNG file.

Be aware of the default values

Even if you don't plan to use this capability, you need to be aware of it. It seems that any time you add an existing image file to the content folder, the Color Key Enabled property will be true by default and the Color Key Color property value will be magenta (255,0,255). If you fail to disable the Color Key Enabled property, all of your pure magenta pixels will be replaced by transparent black pixels.

In the early days of computer graphics, magenta was the defacto standard transparency color. It was referred to as "magic pink."


In this module, I will present and explain an animated sequence in which a UFO flies over an alien planet. You will view the action as if the camerais trained on the UFO while maintaining a constant position relative to the UFO.

As the program runs, the planet gets larger and larger creating the illusion that the UFO is getting closer and closer to the surface of the planet. Finally,the program resets and the sequence repeats.

Questions & Answers

How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
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
How can I make nanorobot?
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
how can I make nanorobot?
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
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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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