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More complex logic

The logic in Listing 8 is fairly complex due mainly to the need to adjust the frame rate from fast to slow or from slow to fast when transitioning between thetwo rows of sprites in Listing 1 . Rather than to try to explain this logic, I am going to leave it as an exercise for the student to analyze the code andto determine where the frame rate transitions occur.


Although I haven't mentioned it before, the SpriteBatch.Draw method (not the Game.Draw method) that will be used to draw the sprites in the game window has a scaling parameter that can be used to scale theimages before drawing them.

Listing 1 declares a variable named scale and sets its value to 4. This will be used as a scale factor when the sprite images are drawn.

The slide variable

Listing 1 also declares a variable named slide and sets its value to 8. This variable is used to control how far the sprite moves each timeit is drawn.

That distance, along with the new sprite position, is computed in Listing 8 as the product of the width of the sprite image and the scale factor divided bythe value of slide . This is a distance that I determined experimentally to cause the animation to look like I wanted it to look.

The sign of the variable named slide

It is worth noting that the sign of the variable named slide determines whether the incremental distance is positive or negative.

It is also worth noting that the change in spritePosition.X only occurs when sprites from the top row in Figure 1 are being drawn. When sprites from the bottom row in Figure 1 are being drawn, the sprite is animated in place.

Move the sprite image back and forth across the game window

The code in Listing 9 causes the sprite image to move back and forth across the game window always facing in the correct direction.

Listing 9 . Move the sprite image back and forth across the game window.

if(spritePosition.X>winWidth - frameWidth * scale) {slide *= -1; spriteEffect = noEffect;}//end if if(spritePosition.X<0){ slide *= -1;spriteEffect = flipEffect; }//end if}//end if//-----------------------------------------------// //New code ends here.base.Update(gameTime); }//end Update

Test for a collision with an edge

Listing 9 tests for a collision between the sprite and the right edge or the left edge of the game window. If the sprite collides with the right edge, thesign on the variable named slide is changed to cause future incremental distance movements to be negative (from right to left).

If the sprite collides with the left edge, the sign on the variable named slide is changed to cause future incremental distance movements to be positive (from left to right).

The spriteEffect variable

In addition, when the sprite collides with one edge or the other, the value of the spriteEffect variable is set such that the dog will be facing the correct direction as it moves toward the other edge of the game window.

That concludes the explanation of the overridden Update method.

The overridden Draw method

The overridden Draw method selects the correct sprite image by extracting a rectangular area from the sprite sheet and draws the rectanglecontaining the sprite image at a specified location in the game window.

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
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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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