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General background information

While studying the past couple of modules, you have learned how to create and then to improve a class named Sprite from which you can instantiate objects that behave as sprites.

Another improvement

In this module, we will once again improve the Sprite class, this time adding the capability for a sprite to determine if it has collidedwith another sprite. This capability is critical for game development in many areas.

Definition of a collision

Our definition of a collision is based on the bounding rectangles for the images that represent the two sprites. If the rectangles intersect in theircurrent positions, a collision is deemed to have occurred. If they don't intersect, there is no collision.


This program is not yet a game because it doesn't provide player interaction. Instead it is a demonstration program that demonstrates sprite collisiondetection is a rather interesting way.

Figure 1 shows a screen snapshot at three different points in time while the program was running.

An epic battle

The demonstration program chronicles a battle between spiders and ladybugs. When the program starts, there are 200 black widow spiders and five ladybugs onthe web in the game window. (See the top image in Figure 1 .)

Spider and ladybug motion

The spiders move at different speeds in different directions but generally toward the southeast. When a spider goes outside the game window on the rightside or the bottom, it reappears on the left side or the top.

The ladybugs also move at different speeds in different directions but generally toward the northwest. When a ladybug goes outside the game window onthe left side or the top, it reappears on the right side or on the bottom.

The spiders don't die easily

When a ladybug collides with a black widow spider, the spider disappears but is reincarnated as a green spider 128 pixels to the right of its originalposition.

When a ladybug collides with a green spider, the spider disappears but is reincarnated again as a small brown spider 128 pixels to the right of itsoriginal position.

The death blow

Finally, when a ladybug collides with a brown spider, the spider is eaten and is removed from the population of spiders. Therefore, all of the spiderseventually disappear and the ladybugs continue marching on victorious.

Output screen images

The top image

The top image in Figure 1 was taken shortly after the program began running. Therefore, the game window was mostly populated with ladybugs and black widowspiders. There are a few green spiders and I believe I see one brown spider at the very bottom border near the right side.

Figure 1 . Screen output at three different times while the program was running.

missing image

The middle image

The middle image in Figure 1 shows the program output after the program has been running for awhile. At this point in time, the game window is mainlypopulated with ladybugs, green spiders, and brown spiders. However, there are a few black widow spiders still in the picture.

The bottom image

The bottom image shows the program output at an even later point in time. At this point, the game window is populated with ladybugs, one green spider and afew brown spiders. Given enough time and a little luck, the ladybugs will collide with and destroy even these remaining spiders.

Questions & Answers

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
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.
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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