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The code in Listing 8 is essentially the same as code that I explained in an earlier module so no explanation beyond the embedded comments should benecessary.

The overridden Update method

The overridden Update method begins in Listing 9 .

Listing 9 . Beginning of the overridden Update method.

protected override void Update(GameTime gameTime) {//Tell all the spiders in the list to move. for(int cnt = 0;cnt<spiders.Count;cnt++) { spiders[cnt].Move(gameTime); }//end for loop//Tell all the ladybugs in the list to move. for(int cnt = 0;cnt<ladybugs.Count;cnt++) { ladybugs[cnt].Move(gameTime); }//end for loop

The code in Listing 9 is essentially the same as code that I have explained in earlier modules, so no further explanation should be necessary.

A for loop that controls the collision testing

Listing 10 shows the beginning of a for loop that causes each ladybug Sprite object to test for a collision with the spiders in the list of spiders once during each iteration of the game loop.

If a ladybug detects a collision with a spider, the action described earlier is taken.

Listing 10 . Beginning of a for loop that controls the collision testing.

for(int cnt = 0;cnt<ladybugs.Count;cnt++) {

Not every spider is tested during each iteration

If a ladybug detects a collision with a spider, the remaining spiders in the list are not tested by that ladybug during that iteration of thegame loop. In other words, if a ladybug's rectangle intersects the rectangles belonging to two or more spiders, only the spider closest to the top of the listwill register a collision.

Test for a collision

The code that tests for a collision is shown in Listing 11 .

Listing 11 . Test for a collision.

//Test for a collision between this ladybug and // all of the spiders in the list of spiders.Sprite target = ladybugs[cnt].IsCollision(spiders); if(target != null) {//There was a collision. Cause the spider to // move 128 pixels to the right.target.Position = new Vector2(target.Position.X + 128,target.Position.Y);

The first statement in Listing 11 calls the IsCollision method on the current ladybug object, passing a reference to the list of spiders as a parameter. As you learned earlier,this will cause the ladybug object to test each spider in the list for a collision until either a collision is found or the list is exhausted.

Return a reference to a spider or null

When the IsCollision method returns and control moves to the beginning of the if statement, the variable named target will either contain null , (meaning that no collision was detected), or will contain a reference to thespider object involved in a collision.

If a collision was detected...

The body of the if statement shown in Listing 11 is executed if a collision was detected and the target variable does not contain null. In this case, the X component of the spider's position vector isincreased by a value of 128. This will cause the spider to move 128 pixels to the right the next time it is drawn.

Questions & Answers

what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
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
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
How can I make nanorobot?
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
how can I make nanorobot?
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.
Berger describes sociologists as concerned with
Mueller 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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