# 0.15 Xna0128-improving the sprite class  (Page 5/11)

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## A collision with an edge of the game window

The code in Listing 8 checks for a collision with an edge of the game window.

If the sprite collides with an edge, the code in Listing 8 causes the sprite to wrap around and reappear at the opposite edge, moving at the same speed in adifferent direction within the same quadrant as before. In other words, if a sprite is moving down and to the right and collides with the right edge of the window, it will reappear at the left edge, still movingdown and to the right but not in exactly the same direction down and to the right.

Listing 8 . Process a collision with an edge of the game window.

if(position.X<-image.Width){ position.X = windowSize.X;NewDirection(); }//end ifif(position.X>windowSize.X){ position.X = -image.Width/2;NewDirection(); }//end ifif(position.Y<-image.Height) { position.Y = windowSize.Y;NewDirection(); }//end ifif(position.Y>windowSize.Y){ position.Y = -image.Height / 2;NewDirection(); }//end if on position.Y}//end if on elapsed time }//end Move

## Modify the position and call the NewDirection method

In all cases shown in Listing 8 , if a collision occurs, the position of the sprite is modified to position the sprite at the opposite edge. Then the methodnamed NewDirection is called to modify the direction pointed to by the direction vector.

The NewDirection method is declared private to prevent it from being accessible to code outside the Sprite class becauseit has no meaning outside the Sprite class.

## The end of the Move method

Listing 8 signals the end of the Move method.

## The method named NewDirection

The method named NewDirection begins in Listing 9 .

Listing 9 . Beginning of the method named NewDirection.

private void NewDirection() { double length = Math.Sqrt(direction.X * direction.X + direction.Y * direction.Y);Boolean xNegative = (direction.X<0)?true:false; Boolean yNegative = (direction.Y<0)?true:false;

## The length of the direction vector and the signs of thecomponents

Listing 9 begins by determining the length of the current direction vector along with the signs of the X and Y components of the vector.

## Compute the hypotenuse

The first statement in the method in Listing 9 calls the Math.Sqrt method and uses the Pythagorean Theorem to compute the length of the hypotenuse of the right triangle formed by the Xand Y components of the direction vector. This is the length of the direction vector.

## Use the conditional operator

Then the last two statements in Listing 9 use the conditional operator to determine if the signs of the components are negative. If so, the variables named xNegative and/or yNegative are set to true.

## Compute components of a new direction vector

Having accomplished that task, the code in Listing 10 computes the components for a new direction vector of the same length with the X and Y components having random (but consistent) lengths and the same signs asbefore.

## Compute a new random value for the X component

For the code in Listing 10 to make any sense at all, you must know that the call to random . NextDouble returns a pseudo-random value, uniformly distributed between 0.0 and 1.0.

can someone help me with some logarithmic and exponential equations.
20/(×-6^2)
Salomon
okay, so you have 6 raised to the power of 2. what is that part of your answer
I don't understand what the A with approx sign and the boxed x mean
it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
Salomon
I'm not sure why it wrote it the other way
Salomon
I got X =-6
Salomon
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x-6
oops. ignore that.
so you not have an equal sign anywhere in the original equation?
Commplementary angles
hello
Sherica
im all ears I need to learn
Sherica
right! what he said ⤴⤴⤴
Tamia
what is a good calculator for all algebra; would a Casio fx 260 work with all algebra equations? please name the cheapest, thanks.
a perfect square v²+2v+_
kkk nice
algebra 2 Inequalities:If equation 2 = 0 it is an open set?
or infinite solutions?
Kim
The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
Al
y=10×
if |A| not equal to 0 and order of A is n prove that adj (adj A = |A|
rolling four fair dice and getting an even number an all four dice
Kristine 2*2*2=8
Differences Between Laspeyres and Paasche Indices
No. 7x -4y is simplified from 4x + (3y + 3x) -7y
is it 3×y ?
J, combine like terms 7x-4y
im not good at math so would this help me
yes
Asali
I'm not good at math so would you help me
Samantha
what is the problem that i will help you to self with?
Asali
how do you translate this in Algebraic Expressions
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
what's the easiest and fastest way to the synthesize AgNP?
China
Cied
types of nano material
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
what is nanomaterials​ and their applications of sensors.
what is nano technology
what is system testing?
preparation of nanomaterial
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
what is system testing
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
can nanotechnology change the direction of the face of the world
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
how did you get the value of 2000N.What calculations are needed to arrive at it
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