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General background information

When we finished the previous module, we were missing one critical element needed to write a simple game program: user input . We were also lacking some other tools that would make it possible for us tocreate more interesting 2D arcade-style games including the ability to create on-screen text.

In this module, you will learn how to program for user input with the keyboard and the mouse. You will also learn how to create on-screen text.

Preview

The program that I will explain in this module is a simple game in which ten spiders attempt to traverse their web from top to bottom. Two largeladybugs are there to eat them if possible. (See Figure 1 .) The objective of the game is to prevent as many of the spiders as possible from making it tothe bottom of the game window.

Figure 1 shows a reduced view of the game window shortly after the game is started and before any spiders make it to the bottom.

Figure 1 . Reduced view of the game window.

missing image

Spider behavior

The spiders move at different speeds in different directions but generally towards the southeast. If a spider makes it to the bottom, it is counted ashaving crossed the finish line. That spider wraps back up to the top and starts the journey again. If a spider hits the right edge of the window, it wrapsaround to the left edge and continues the journey.

The ladybugs

The movements of the ladybugs are under the control of the player. If the player causes a ladybug to collide with a spider, the spider is eaten andremoved from the spider population.

Using the keyboard

The player can move the ladybugs using either the keyboard or the mouse. Pressing the four arrow keys causes one of the ladybugs to move in thecorresponding directions. Pressing two arrow keys at the same time causes the ladybug to move in a diagonal direction.

Holding down the A key and pressing the arrow keys causes the other ladybug to move.

Using the mouse

Pressing the left mouse button makes it possible to drag a ladybug with the mouse. Pressing the right mouse button makes it possible to drag the otherladybug with the mouse. Pressing both mouse buttons makes it possible to drag both ladybugs with the mouse.

Difficulty level

The game has only one level. I personally find it very difficult to prevent all ten spiders from making it to the bottom using the arrow keys only. On theother hand, it is easy to defeat the spiders by dragging a ladybug with the mouse.

A useful student project

A useful student project would be to upgrade the program to provide varying levels of difficulty. This could be accomplished by changing the speed of the spiders, changing the number of spiders, or a combination ofthe two.

Alternatives to the arrow keys

Another useful student project would be to define alternatives to the arrow keys, such as the keys labeled 4, 8, 6, and 2 on the keypad, or four keys in adiamond pattern on the left side of the keyboard.

Discussion and sample code

As usual, I will break this program down and explain it in fragments. However, I will only explain those portions of the code that are substantiallydifferent from code that I have explained in earlier modules.

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, Xna game studio. OpenStax CNX. Feb 28, 2014 Download for free at https://legacy.cnx.org/content/col11634/1.6
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