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A collision with an edge of the game window

The code in Listing 8 checks for a collision with an edge of the game window.

If the sprite collides with an edge, the code in Listing 8 causes the sprite to wrap around and reappear at the opposite edge, moving at the same speed in adifferent direction within the same quadrant as before. In other words, if a sprite is moving down and to the right and collides with the right edge of the window, it will reappear at the left edge, still movingdown and to the right but not in exactly the same direction down and to the right.

Listing 8 . Process a collision with an edge of the game window.

if(position.X<-image.Width){ position.X = windowSize.X;NewDirection(); }//end ifif(position.X>windowSize.X){ position.X = -image.Width/2;NewDirection(); }//end ifif(position.Y<-image.Height) { position.Y = windowSize.Y;NewDirection(); }//end ifif(position.Y>windowSize.Y){ position.Y = -image.Height / 2;NewDirection(); }//end if on position.Y}//end if on elapsed time }//end Move

Modify the position and call the NewDirection method

In all cases shown in Listing 8 , if a collision occurs, the position of the sprite is modified to position the sprite at the opposite edge. Then the methodnamed NewDirection is called to modify the direction pointed to by the direction vector.

The NewDirection method is declared private to prevent it from being accessible to code outside the Sprite class becauseit has no meaning outside the Sprite class.

The end of the Move method

Listing 8 signals the end of the Move method.

The method named NewDirection

The method named NewDirection begins in Listing 9 .

Listing 9 . Beginning of the method named NewDirection.

private void NewDirection() { double length = Math.Sqrt(direction.X * direction.X + direction.Y * direction.Y);Boolean xNegative = (direction.X<0)?true:false; Boolean yNegative = (direction.Y<0)?true:false;

The length of the direction vector and the signs of thecomponents

Listing 9 begins by determining the length of the current direction vector along with the signs of the X and Y components of the vector.

Compute the hypotenuse

The first statement in the method in Listing 9 calls the Math.Sqrt method and uses the Pythagorean Theorem to compute the length of the hypotenuse of the right triangle formed by the Xand Y components of the direction vector. This is the length of the direction vector.

Use the conditional operator

Then the last two statements in Listing 9 use the conditional operator to determine if the signs of the components are negative. If so, the variables named xNegative and/or yNegative are set to true.

Compute components of a new direction vector

Having accomplished that task, the code in Listing 10 computes the components for a new direction vector of the same length with the X and Y components having random (but consistent) lengths and the same signs asbefore.

Compute a new random value for the X component

For the code in Listing 10 to make any sense at all, you must know that the call to random . NextDouble returns a pseudo-random value, uniformly distributed between 0.0 and 1.0.

Questions & Answers

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
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.
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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