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Listing 6 . Test for a collision.
boolean collision = thisSprite.isCollision(redBallSprite);

What is a collision?

There are many ways to define and implement collision detection in game and simulation programming. In this program, a collision is deemed to haveoccurred if any portion of the rectangular redBallImage overlaps any portion of the rectangular greenBallImage . (Even though these images appear to be round, they are drawn on a transparent rectangular background.)

The isCollision method of the Sprite01 class

The isCollision method of the Sprite01 class is shown in Listing 7 .

Listing 7 . The isCollision method of the Sprite01 class.
public boolean isCollision(Sprite01 other){ //Create variable with meaningful names make the// algorithm easier to understand. Can be eliminated // to make the algorithm more efficient.float thisTop = Y; float thisBottom = thisTop + height*scale;float thisLeft = X; float thisRight = thisLeft + width*scale;float otherTop = other.getY();float otherBottom = otherTop + other.getHeight()*other.getScale(); float otherLeft = other.getX();float otherRight = otherLeft + other.getWidth()*other.getScale(); if (thisBottom<otherTop) return(false); if (thisTop>otherBottom) return(false);if (thisRight<otherLeft) return(false); if (thisLeft>otherRight) return(false);return(true); }//end isCollision


This method detects a collision between the rectangular sprite object on which the method is called and another rectangular sprite object.

The methodology is to test four cases where acollision could not possibly have occurred and to assume that a collision has occurred if none of those casesare true.

Given that as background, you should be able to use a pencil and paper along with the code in Listing 7 to draw some rectangles and understand how the code in Listing 7 works.

Although I can't guarantee that the method won't call a collision when no collision actually occurred, I am pretty sure that it won't miss any collisionsthat do occur.

Process a collision

The code in Listing 8 is executed when the call to the isCollision method returns true. Therefore, this code processes a collision only when one has occurred.

The code excludes collisions between the red sprite and itself, (which is an artifact of the algorithm) . It also excludes collisions between the red sprite and blue sprites (if they exist) .

Listing 8 . Process a collision
if((collision == true)&&(! thisSprite.getImage().equals(redBallImage))&&(! thisSprite.getImage().equals(blueBallImage))){ //A collision has occurred, change the color of// this sprite to blue and maybe cause it to // die and be removed from the population.thisSprite.setImage(blueBallImage); if(dieOnCollision){thisSprite.setLife(0); }//end if//Cause the redBallSprite to change direction on// a random basis. redBallSprite.setXDirection((random.nextFloat()>0.5) ? 1f : -1f); redBallSprite.setYDirection((random.nextFloat()>0.5) ? 1f : -1f);//Cause the redBallSprite to change stepsize on a // random basis.redBallSprite.xStep = 0.1f+random.nextFloat()*2.0f;redBallSprite.yStep = 0.1f+random.nextFloat()*2.0f;//Cause the redBallSprite to grow largerredBallSprite.setScale(redBallSprite.getScale() + (redBallSprite.getScale()) * 0.001f);//Play a sound to indicate that a collision has // occurred.blaster.play(); }//end if}//end for loop

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
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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
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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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