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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

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
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.
Damian
yes that's correct
Professor
I think
Professor
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
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
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
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
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
Praveena Reply
hi
Loga
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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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