<< Chapter < Page Chapter >> Page >

Why change the spider's position?

This change is position is necessary to prevent the same ladybug from registering a collision with the same spider during the next iteration of thegame loop. The forward movement of the spiders and the ladybugs each time they move is less than the dimensions of the intersecting rectangles. Therefore,without a purposeful shift in position of either the ladybug or the spider, the pair would continue to register collisions until the rectangles finally separatefrom one another.

Spiders don't die easily

As you read in the Preview section, if a black widow spider collides with a ladybug, it simply moves 128 pixels tothe right and changes into a green spider. If a green spider collides with a ladybug, it simply moves 128 pixels to the right and changes into a brownspider. Finally, if a brown spider collides with a ladybug, it is eaten and removed from the population of spiders. This is accomplished by the code in Listing 12 .

Listing 12 . Spiders don't die easily.

//If the collision was with a black widow // spider, cause it to reincarnate into a// green spider. if(target.Image.Name == "blackWidowSpider") {target.SetImage("greenspider",Content); }//If the collision was with a green spider, // cause it to reincarnate into a brown// spider. else if(target.Image.Name == "greenspider") {target.SetImage("brownSpider",Content); }//If the collision was with a brown spider, // it gets eaten. Remove it from the list of// spiders. else if(target.Image.Name == "brownSpider") {spiders.Remove(target); }// end else-if}//end if }//end for loopbase.Update(gameTime); }//end Update method

The code in Listing 12 is relatively straightforward.

The Name property

The first statement in Listing 12 shows why I needed to set an identifiable string value into the Name property of the Texture2D object referred to by image in Listing 2 and Listing 3 . I needed a way to determine the type of spider involved in each collision so that I could take the appropriate action when acollision was detected.

Killing the brown spider

The call to the spiders.Remove method in Listing 12 removes the target Sprite object's reference from the list of spiders. Since this is the only reference to the Sprite object, this action should make the memory occupied by the Sprite object eligible for garbage collection.

Is a Dispose Method needed?

However, I'm not certain that garbage collection is sufficient to free up all of the resources owned by the now defunct object and its image. It might also beadvisable to use a Dispose Method . At the time I am writing this, I simply don't know.

The end of the Update method

Listing 12 also signals the end of the overridden Update method.

The overridden Game.Draw method

The overridden Game.Draw method is shown in its entirety in Listing 13 .

Listing 13 . The overridden Game.Draw method.

protected override void Draw(GameTime gameTime) { spriteBatch.Begin();spiderWeb.Draw(spriteBatch);//draw background //Draw all spiders.for(int cnt = 0;cnt<spiders.Count;cnt++) { spiders[cnt].Draw(spriteBatch); }//end for loop//Draw all ladybugs. for(int cnt = 0;cnt<ladybugs.Count;cnt++) { ladybugs[cnt].Draw(spriteBatch); }//end for loopspriteBatch.End(); base.Draw(gameTime);}//end Draw method //-------------------------------------------------//}//end class }//end namespace

Questions & Answers

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.
what is biological synthesis of nanoparticles
Sanket Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get the best Algebra and trigonometry course in your pocket!

Source:  OpenStax, Xna game studio. OpenStax CNX. Feb 28, 2014 Download for free at https://legacy.cnx.org/content/col11634/1.6
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Xna game studio' conversation and receive update notifications?