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Random values

Note that several of the properties of each Sprite01 objects is initialized with random values.

The use of the nextFloat method of the object of the Random class may be new to you. If so, this method simply returns a random value between 0.0f and 1.0f each time it is called.

The conditional operator

If the use of the conditional operator involving the ? character and the : character is new to you, you will probably need to do some online researchin order to understand the use of this operator.

Otherwise, the code in Listing 4 is straightforward and shouldn't require an explanation beyond the embedded comments.

Listing 4 signals the end of the init method.

The update method

The update method is shown in its entirety in Listing 5 .

Listing 5 . The update method.
public void update(GameContainer gc, int delta) throws SlickException{//Do the following for every sprite in the array for(int cnt = 0;cnt<sprites.length;cnt++){ //Ask each sprite to move.sprites[cnt].move();//Ask each sprite to bounce off the edge if // necessary.sprites[cnt].edgeBounce(backgroundWidth,backgroundHeight); }//end for loop}//end update

Move and bounce

Listing 5 uses a for loop to access each of the sprite objects, asking each object to move and to bounce off the edge of the game window if necessary.

Listing 5 could hardly be simpler. That is because the necessary complexity has been encapsulated in each object of the Sprite01 class.

The move method of the Sprite01 class

Listing 6 shows the move method from the class named Sprite01 .

Listing 6 . The move method of the Sprite01 class.
public void move(){ X += xDirection*xStep;Y += yDirection*yStep; }//end move

The code in Listing 6 is also simple. However, in this case, the simplicity is somewhat deceiving. The apparent simplicityderives from the fact that the four required property values are routinely maintained by the object and are readily available to the two statements inthe move method when needed.

The edgeBounce method of the Sprite01 class

The edgeBounce method of the Sprite01 class is shown in Listing 7 . It is not simple.

Listing 7 . The edgeBounce method of the Sprite01 class.
public void edgeBounce(float winWidth,float winHeight){ //Test for a collision with one of the edges and// cause to sprite to bounce off the edge if a // collision has occurred.if(X + width*scale>= winWidth){ //A collision has occurred.xDirection = -1.0f;//reverse direction //Set the position to the right edge less the// width of the sprite. X = winWidth - width*scale;}//end if//Continue testing for collisions with the edges // and take appropriate action.if(X<= 0){ xDirection = 1.0f;X = 0; }//end ifif(Y + height*scale>= winHeight){ yDirection = -1.0f;Y = winHeight - height*scale; }//end ifif(Y<= 0){ yDirection = 1.0f;Y = 0; }//end if}//end edgeBounce

Code that you have seen before

Listing 7 contains essentially the same code that was written into the update method of the earlier module mentioned above . In this case, however, all of the complexity has been encapsulated into the Sprite01 class and replaced by a single call to the edgeBounce method in the update method of the program named Slick0200 . Thus, the program's update method is now much simpler.

Questions & Answers

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
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Anatomy of a game engine. OpenStax CNX. Feb 07, 2013 Download for free at https://legacy.cnx.org/content/col11489/1.13
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