C# Xna Made Easy Tutorial 5 - Keyboard Input Video Lecture | C# Game Development: Game Making made Easy (English)

hello everybody and welcome to your next
tutorial in this tutorial you will be
learning about keyboard input and the
next tutorial will be on gamepad input I
won't be teaching touchpad input because
this isn't for on the Windows Phone
these aren't Windows Phone tutorials so
anyways let's go to the top of our code
as you see we still have our texture
I'll go to texture from our past
tutorials and you have the vector to
position possession to and we add a new
I've added a new variable called move
speed and equal to 500 okay so let's um
another variable I declared is keyboard
state um
the class keyboard state and I'm sorry
and this guy named it key state now
notice that keyboard state is part of
the input names bits input name face so
if you were to put this into another
class or another CSV file or whatever
then you have to put the input namespace
just you know so when the initialize we
same initialize in this lodging position
in position two and the load content our
method we're loading the image same as
before nothing new so the update is
something new so in the update method
you're gonna be learning a lot of things
today first thing we set our keyboard
state and renamed it key state right but
we have to let on our program know that
we want to actually get um start
checking the keyboard to see for p
presses right so in the update method
notice update
we want to put keyboard equal m key
state equals keyboard get state so this
basically means that we want to get the
state of the keyboard and detect key
presses basically that's what the same
so what we do is that since key state is
equal to keyboard I get state then it's
ready to detect key presses from the
keyboard
so we basically um it has a lot of
built-in functions you'll put a lot of
it goes in methods my bad so you check
the keyboard is down um if the key
presses up and um these are other you
can get the press keys as like a array
of press keys if you want to do like
attack combos or something if you want
to get an array of the press keys for a
combo or whatever and you can get other
different defaults from the C sharp
language so right now we want to move
our box or our image so we're saying
that if the key key state dot is key
down keys dot right so if I let me
delete this first one right here and let
me rewrite it so if I put if key state
and it's a good thing to have
intellisense because intellisense really
helps you out by showing your options so
it's key down and then you put keys now
keys is a part of the class I believe
and you put dot and you can see all the
options all the different keys you can
choose from so right now I want to put
key right so if it's the right arrow key
is being pressed then we want to do
something in this case you want to move
the box towards the right side of the
screen so since um
we have our our x and y student a vector
then we do like this we put a position
dot X so we're getting the x coordinate
of the vector plus equals and if you
don't know what that means then go back
to your C sharp basics I'm going to put
movie
remember that's a new variable that we
created at the beginning times put the
float cast and then we're gonna put game
time dot elapsed game time dot total
seconds now you guys are probably saying
what the hell is that well okay if you
look here at the top of the update
method you see game time and then you
see they can name a game ton so
basically game time is usually
calculated basically what it states the
game time certain times in the game
and so if you go to game time you see
dot you can get that labs game time
missus running slowly the total game
time or even playing and basically a
laps game time is how much um if you
read it it basically says okay sorry if
you read it says the amount of elapsed
time since the last update so every
every time that updates it resets it
back to zero again and it calculates how
much time has passed since the last
update right and then we get the total
seconds from that last um from the last
update so I guess they rounded up or
whatever so basically why do we do this
why do we do most B times the the actual
time right and we do this because it's
basically for frame rate when you move
according to frame rate then it doesn't
matter what speed the PC is running at
it will run at the same speed on every
single computer and you can ensure that
there's no like eNOS or anything because
we run at the same speed no matter what
processing speed it is and the good
thing a good habit to get into cuz
there's some powerful pcs that will run
the game twice the speed or maybe even
three times the speed that you want to
run it at and it won't run efficiently
and then that's why some games some
people can hack it or do like increase
the frames per second or increase
something and then their game runs at
double the speed and then
can be you in certain games to the
growing fashion this is the reason why
and with this method you'll prevent that
now another thing to know is that if you
look at the distance formula in physics
the distance formula I believe it's
distance is equal to velocity time times
time right so this is the distance you
want to travel what the position is yeah
the position on the screen we want to
travel a certain distance so it's equal
to the velocity which is a moon speed
times the time and then there you will
get the adequate amount of distance
where you want to move and not a lot of
time right so if that's just a little
physics lesson for you guys to learn
from that so basically we do the same
things we're basically moving this
towards the right if they press left we
do minus equals we want to move towards
the left if they press up then we do
minus equals because remember when we're
doing we're working with X name the the
zero zero coordinates at the top left
corner meaning that if you go up the
screen you're going you you're going the
higher of the screen the lower the
number is the lower is on screen the
higher the number is so then if we press
the down key then we're moving down
towards the screen so we add it to our
position Y and then our draw method is
exact same arm we draw the first image
in the second image and let's run this
program so as you can see it might move
a little laggy because it does recorder
but basically is like this so when I put
the right arrow key it moves towards the
right when I move the left arrow key
moves towards the left when I click down
a moose down when I move up it moves up
when I press the upper chin is up and
then there you got player movement so
this is it for the tutorial I hope you
enjoyed it and one more thing you may
not when you notice when you close the
window you always have to click the X
button what you might also want to click
the escape button to close
the game window also so basically you
could put or you can put and keyboard
dot get state dot is key down keys dot
escape and you see what I did there I
could have used the key state variable
but the key state is just a holder for
keyboard get state so we don't actually
have to use a key state variable I can
put keyboard get state and still do the
same functionality this just makes the
code shorter and easier for you to
understand but either way can work for
you and either way will be fine so then
if I run this program one more time
and I press the Escape key the window
closes as well so I hope you enjoy this
tutorial the next tutorial is gonna be
on gamepad input as you can see it's
come um commented here so I'll uncomment
it and show you all this code and stuff
so hope you enjoyed this tutorial thanks
for watching and bye