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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

where we get a research paper on Nano chemistry....?
Maira Reply
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
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..
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
ya I also want to know the raman spectra
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.
yes that's correct
I think
Nasa has use it in the 60's, copper as water purification in the moon travel.
nanocopper obvius
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
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
analytical skills graphene is prepared to kill any type viruses .
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
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.
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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