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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

Methodology

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

where we get a research paper on Nano chemistry....?
Maira Reply
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..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
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
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
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
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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