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Adding Sprite object references to the list

Listing 8 shows the beginning of an if statement in which a new Sprite objects reference will be added to the list every eighth iteration (frame) of the game loop until all 24 sprites have been added.

Note that a frame counter named frameCnt is declared and initialized to zero in Listing 5 and is incremented near the end of the overridden Update method in Listing 12 .

Instantiate new Sprite objects

The code in Listing 9 uses the modulus (%) operator to identify every eighth iteration of the game loop and to instantiate a new Sprite object during those iterations.

Listing 9 . Instantiate new Sprite objects.

if(frameCnt % 8 == 0) { //Instantiate a new sprite every 8th frame.if((sprites.Count) % 2 == 0) { //Even numbered spritessprites.Add(new Sprite("blueball",Content)); }else { //Odd numbered spritessprites.Add(new Sprite("redball",Content)); }//end else}//end if on frameCnt }//end if on sprites.Count

The modulus operator

In case you have forgotten, the modulus operator returns the remainder of a division instead of returning the quotient. If an integer value is divided by 8,the returned value is 0 only when the integer value is a multiple of 8. (Also by definition, 0 % 8 returns 0.)

Every eighth iteration

Therefore, the conditional expression in the first if statementin Listing 9 will allow the statements contained in the body of the if statement, (which instantiate new Sprite objects), to be executed only during every eighth iteration of the game loop.

Further, the conditional expression in Listing 8 will not allow the code in Listing 9 to be executed after 24 Sprite objects have been instantiated.

Even and odd sprite images

The conditional expression in the second if statement in Listing 9 causes the new Sprite objects that are instantiated to alternate between the "blueball" and "redball" images shown in Figure 1 .

Make all the existing sprites move

Listing 5 declares an instance variable named moveLim and sets its value to 200. The code in Listing 10 causes all of the existing sprites to move to the right and down if the value of the frame counter is less than 200.

Listing 10 . Make all the existing sprites move.

if(frameCnt<moveLim) { for(int cnt = 0;cnt<sprites.Count;cnt++) { sprites[cnt].Position = new Vector2( 10 * cnt + frameCnt,10 * cnt + frameCnt);}//end for loop }//end if

Use a for loop

The code in Listing 10 uses a for loop to access each of the Sprite object references currently stored in the list, iterating from 0 to one less than the count of references stored in the listgiven by sprites.Count .

Put a new value in the Position property

Once a Sprite object's reference has been accessed, Listing 10 sets the Position property stored in the object to a new Vector2 object for which the X and Y values have been modified on the basis of the frame counter.

The new X and Y values cause the object to be drawn a little further down and to the right the next time it is drawnrelative to its current position. This causes the entire diagonal line of Sprite objects to move down and to the right in the game window.

Questions & Answers

How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
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 .?
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Stoney Reply
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Adin Reply
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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.
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Damian Reply
absolutely yes
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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.
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
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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