How to make a Video Game in Unity - PROGRAMMING (E02) Video Lecture | Build a Game: Unity Tutorial (English) - Game Development

today we'll get started programming in
unity I did a poll asking what language
you guys would like to see and the
results were well conclusive so today
we'll be creating our first script we'll
have a look at how you can change
properties and even add forces to an
object so I'm really excited let's just
jump right in turn so whenever we want
to program in unity we create what is
called a script to do this we click on
the object that we wanted to sit on in
our case the player and we hit add
component then we go down here select
new script and we can give a name to our
script in our case it's going to be
something like player movement but you
can really choose anything you'd like
and we select the language in our case
that's going to be C sharp so it create
an ad and you can see that unity adds a
new component and that's because scripts
and unity are pretty much just custom
components that we get to tell what to
do it's also created a script file down
here in the project panel and that means
that we can add it to other objects as
well so if we now select our ground we
can drag our player movement onto that
in order to make it affect the ground as
well but we don't want to do that so
that's just right click on it and hit
remove component so if we go back to a
player and double click on our player
movement script it's going to open up in
your script editor if you're on Windows
that's either going to be visual studio
which is what I'm using or monodevelop
which is also what you're going to be
using on the Mac it's really up to
personal preference and you're going to
be able to follow along just fine with
either so this is what a script looks
like just when we created that's a lot
of scary stuff going on here the thing
about learning to program is that at
first you're just going to have to
ignore most of the stuff that's going on
to clean it up a little bit we can go
ahead and delete the tooth using tags up
here and really the only thing that you
should focus on right now is these two
functions where it says void start and
void update and these are created by
unity automatically so let's have a look
at the start function up here the neat
thing about the start function is that
it will run when your game starts that
means that whatever code you put between
this curly bracket and this curly
brackets that means in here is going to
be executed when you start the game do
note that in c-sharp it doesn't matter
how many spaces you have you can really
space it out any way you want you can
even put it on separate lines as long as
you don't split up a void like this
let's just try and see if this is
working by displaying a message to
ourselves to do that we write debug the
log and make sure to have capital
letters the same places that I do
because c-sharp is cap sensitive
then we open up a parenthesis and you
can see that it automatically closes one
as well then in quotation marks we get
to write a message in our case we'll
just write something like hello world
make sure you end this line with a
semicolon you're going to be doing that
a lot whenever you write a command
you're going to end it with a semicolon
if we now save this by hitting ctrl s
you can see that it saves up here hit
back into unity and hit play nothing is
really going to happen in our game view
however if we go ahead and look at the
console here you can see that it now
says hello world if you don't already
have the console open you can go window
and then console so the console here is
used by us to debug our code it allows
us to write messages by using debug
deadlock followed by our message and it
also displays warnings and errors about
the code to rewrite so we really have a
love-hate relationship to the console if
something isn't working in your game
make sure to check the console and see
if there's any errors of warnings they
might help you troubleshoot the problem
all right so writing hello world in the
console is a bit boring let's have a
look at what else we can do well in fact
we can do pretty much anything in unity
we can modify values we can add forces
to objects we can add explosions create
game timers and menus the possibilities
are pretty much endless and that's also
kind of what makes programming scary is
that you have a lot of functionality
available to you but let's try and focus
on a specific problem so let's say that
we want to go into a rigidbody and
disable gravity for that object to do
that we need first of all to reference
this rigidbody component and unity makes
that really easy if we go into our
script and go above our functions on
this empty space here create some new
lines and then write public then the
name of a component our component is
called rigidbody
then the name of the component that we
want to modify in our case rigidbody and
now we need to give this reference a
name that will use internally so we can
call it something like RB for rigidbody
if we save that and hit back into unity
we should now see an empty slot here
with the name of RB we can then take our
rigidbody and drag it into that slot so
now whenever we write RB in our script
it's going to refer to this particular
rigid body that means that if we go back
into visual studio and instead of
writing debug that lock here write
something like our B dot used
we can set that equal to either true or
false
in our case we're going to set it to
false and then of course end with a
semicolon so say that that's it in a
unity and let's see if this value isn't
going to change when we have play so
let's hit play and indeed the use
gravity changes to false we can see that
our cube here is hovering in the air and
if we were to duplicate him so that the
two would collide you can see just how
cool of an effect that already gives us
but this is just editing a tiny little
property we can also make our rigidbody
do different things if we quit playing
go back into visual studio we can
actually add a force to that rigidbody
so instead of writing our BTUs gravity
let's write RB add force and again we
open a parenthesis close the parentheses
and then end with the semicolon however
you can currently see that this is
displaying red and the reason why is
that we need to specify a few things
these are called function arguments the
add force method wants to know how much
force it should add in the different
directions so we could start with 0 on
the x-axis we could do something like
200 on the Y and maybe 500 on the Z
notice how I separate each number with a
comma we can then hit save go back into
unity and when we now play we should see
a force being applied to this object
awesome so let's stop playing head back
into visual studio and what we want to
do is not only add a force in the
beginning of the game we want to add a
constant force in order to move our
object forward to do that we can't use
the start method remember this is only
called once right when we start the game
however our update function is called
once per frame that means that whenever
the computer draws a new image and it
does this multiple times a second this
function is going to run so let's again
put this on a new line to make things a
bit easier to see and we can then write
RB dot add force just like we did up
here we can input 0 on the x 0 on the y
let's try 200 on the Z again remember to
close it with a semicolon it's also take
our entire start function up here and
remove it so now we hit save go back
into unity hit play and we should see
our cube just launching into the
distance and indeed we do however even
though our game currently runs just fine
and we get no errors in the console we
do actually have an error in our code if
we stop playing head back into visual
studio we can see that everything looks
just fine but that's one
and that is if this method is called
once per frame and we add a fixed amount
of force each frame how much force we
add over a second is actually going to
totally depend on our frame rate that
means if you have a really good computer
that is drawing a bunch of frames a
second the cube is going to travel
faster than on a slower computer that
doesn't run as many frames per second
and the frame rate can even vary on the
same computer if a bunch of stuff is
going on on the screen the computer
usually slows down a bit in order to
handle everything or if something is
happening in the background that might
also change your frame rate so in order
to even out these differences what we do
is we multiply this value the 200 here
with what is called time.deltatime this
is a bit confusing but basically what
time delta time is is the amount of
seconds since the computer drew the last
frame so if the update is running 10
times per second this value is going to
be 0.1 and if it's running 20 times a
second this value is going to be point
zero five so the higher the frame rate
the lower this value is going to get and
therefore it's going to even out the
advantage that you would get if you were
running on a good computer if you don't
get this right away that's totally
understandable I sure didn't the first
time just right after me for now so if
we now save this and go back into unity
we should actually see a pretty big
difference and that is our cube is not
moving now at all and that's because in
my system it's drawing a lot of frames
and so overall the value gets a lot
smaller than it was before the
workaround for this is super simple we
just need to go into our script and make
this value bigger I'm just gonna add
another zero save that going to unity
hit play and we should see him just
storming off here it doesn't look like
much of a difference but now we could at
least know that it looks the same way on
all systems
the final thing we're going to do is yet
another one of those it doesn't look
like it's wrong but it's actually a
little wrong kind of things and that is
that unity really likes it if we use
what is called fixed update instead of
update for calculating physics and in
our case we are using the unity physics
system so just make sure that whenever
you do physics stuff if you're adding
forces or changing velocity do it inside
the fixedupdate
unity likes that a lot better and it's
going to make everything look a lot
smoother when you collide with stuff
also if you find all this confusing I
totally get it one thing that you can do
is use the fact that we can make
comments inside of our code so you can
see this line here is grayed out that's
because it's marked with these two
slashes whenever you create two slashes
and follow it up with some text that
text is not going to be in
fluted in your code and so it allows you
to save stuff like this so just go
through your code and add some comments
to help you out you can even add
comments at the end of a line also see a
lot of beginners using spaces to indent
that code I find it a lot easier to just
use tap but it's something programmers
have argued about for decades so let's
just save our code a final time and
enjoy the result until the next video
you can of course play around with this
by adding more objects into the game
that's add another cube here for example
and this already has a box Collider so
it should actually collide
let's pretty much it for this video I
hope you liked it if you did make sure
to subscribe so you don't miss out on
future episodes I upload on Sundays and
Wednesdays also if you're fan of the
series you can always support me over at
patreon patreon allows you to donate a
monthly amount of your choosing
totally cancelable at any time it's
really awesome so if you want to see
more content like this or just buy me a
cup of coffee
you're very welcome over at patreon.com
slash practice also if you found this
programming episode really really
difficult you can definitely check out
the C sharp beginner course it really
focuses on teaching the c-sharp language
so thanks for watching and I will see
you in the next video thanks to of the
awesome people who donated in January
and especially thanks to Derek heaps
Kirk Chaisson Merrifield James Calhoun
Robert Barnum Peter Locke and Jason
dirty doh if you want to become a patron
yourself you can do so aperture intercom
/ prayer keys thanks a lot guys