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Listing 10 . Compute components of a new direction vector.

//Compute a new X component as a random portion of // the vector length.direction.X = (float)(length * random.NextDouble());//Compute a corresponding Y component that will // keep the same vector length.direction.Y = (float)Math.Sqrt(length*length - direction.X*direction.X);//Set the signs on the X and Y components to match // the signs from the original direction vector.if(xNegative) direction.X = -direction.X;if(yNegative) direction.Y = -direction.Y;}//end NewDirection

The first statement in Listing 10 computes a new value for the X component of the current direction vector, which is a randomportion of the length of the current direction vector ranging from 0 to the full length of the vector.

Compute a consistent value for the Y component

Then the second statement in Listing 10 uses the Sqrt method along with the Pythagorean Theorem to compute a new value for the Y component, which when combined with the new Xcomponent will produce a direction vector having the same length as before.

Adjust the signs of the X and Y components

Finally, the last two statements in Listing 10 use the information gleaned earlier to cause the signs of the new X and Ycomponents to match the signs of the original components.

A new direction vector with the same length in the same quadrant

By modifying the lengths of the X and Y components, the code in Listing 10 causes the direction pointed to by the new vector to be different from thedirection pointed to by the original direction vector.

By causing the X and Y components to have the same signs, the code in Listing 10 causes the new direction vector to point into the same quadrant as before.

The Draw method

The Sprite.Draw method is shown in its entirety in Listing 11 .

Listing 11 . The Sprite.Draw method.

public void Draw(SpriteBatch spriteBatch) { //Call the simplest available version of// SpriteBatch.Draw spriteBatch.Draw(image,position,Color.White);}//end Draw method //-------------------------------------------------//}//end Sprite class }//end namespace

This Draw method is essentially the same as the Draw method that I explained in an earlier module so it shouldn't require further explanation.

To avoid becoming confused, however, you should keep in mind that this program deals with the following three methods having the name Draw :

  • Overridden Game.Draw method.
  • Sprite.Draw method.
  • SpriteBatch.Draw method.

The end of the Sprite class

Listing 11 also signals the end of the Sprite class.

The Game1 class

The Game1 class begins in Listing 12 .

Listing 12 . Beginning of the Game1 class.

namespace XNA0128Proj { public class Game1 : Microsoft.Xna.Framework.Game {GraphicsDeviceManager graphics; SpriteBatch spriteBatch;//Use the following values to set the size of the // client area of the game window. The actual window// with its frame is somewhat larger depending on // the OS display options. On my machine with its// current display options, these dimensions // produce a 1024x768 game window.int windowWidth = 1017; int windowHeight = 738;//This is the length of the greatest distance in // pixels that any sprite will move in a single// frame of the game loop. double maxVectorLength = 5.0;//References to the space rocks are stored in this // List object.List<Sprite>rocks = new List<Sprite>(); int numRocks = 24;//Number of rocks.//The following value should never exceed 60 moves // per second unless the default frame rate is also// increased to more than 60 frames per second. double maxRockSpeed = 50;//moves per second//References to the power pills are stored in // this List.List<Sprite>pills = new List<Sprite>(); int numPills = 12;//Number of pills.double maxPillSpeed = 40;//moves per second //References to the UFOs are stored in this List.List<Sprite>ufos = new List<Sprite>(); int numUfos = 6;//Max number of ufosdouble maxUfoSpeed = 30; //Random number generator. It is best to use a single// object of the Random class to avoid the // possibility of using different streams that// produce the same sequence of values. //Note that the random.NextDouble() method produces// a pseudo-random value where the sequence of values // is uniformly distributed between 0.0 and 1.0.Random random = new Random();

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
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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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