GameMaker Studio - Enemies & HP tutorial Video Lecture - Game Maker Tutorial

alright guys welcome back to our
tutorials on the top-down shooter what
i'm going to start looking at now and
it's been plaguing my mind a little is
exactly how i would start to cover this
is um enemies and like things to
actually shoot at and your top-down
shooter
the reason it's i'm trying to work out
how best to put it is because uh
obviously there's actually a lot of
questions in fall depending exactly how
your game works as to how your enemy
should be and i want to provide the most
sort of generic and most useful methods
of doing things so they can be applied
to those in any different situations as
possible so in the mean time i'm just
going to show you how to make something
that reacts to your bullets and will
lose hit points for example and die and
because that's basically the thing you
want to probably apply no matter how
you're doing EFI's so i mean i mean it
depends exactly like whether or not
you're doing levels are you doing you're
doing like waves of stuff that stuff is
coming forever or it's coming in set
patterns or or how the object wants to
move around so all i'm going to do and
this is make object i'll make it move
downwards because you already know how
to do that and will make it so that when
it takes like four hits it dies and then
you know we'll move on from now we'll
build up something that you know
resembles a proper game or will make the
enemy shoot back and that kind of thing
for now we'll just make it so we'll make
an enemy you shoot it and it dies so I
mean I've already made a little sprite
for our enemy that's just a little red
face
and I put the origin of that spray in
the center so we first of all obviously
just need to make an object for our
enemy
so we BG on the school and me will do
nicely
set the sprite to be SPR on the school
enemy
or whatever you've named your enemies
bright and then just for starters we'll
just place them around the room chances
are you won't actually have I mean that
there's a way of doing enemy waves if
you just built like above your room a
bunch of enemies that would move down
into the room and you would kill them
that kind of thing but chances are you
will have later in your game other
objects that generate like an object
underscore enemy generator for example
that generates the waves or patterns of
enemies that you want sort of thing but
for now we'll just place a few of those
into our level and we'll give them some
code so I'd have been on create we want
them to just you know just make it look
like they're enemies from a top-down
shooter so we'll have them scroll
towards you so if we set our P speed to
equal um just one will do I guess so
they just slowly mooch down the screen
one pixel a frame towards you and we'll
make it so ah oh no we don't want to add
another event and create we want to give
them hit points so we were making our
own variable up now this isn't one of
the variables this hatchery set by the
enemy itself it's not like not like one
of these red variables that actually
sort of mean something to the object
this is a variable we're creating
ourselves so we're going to set head
points on or one you know you could call
it anything you could go ahead and hit P
or whatever you want just gonna use HP
for now we're going to say HP to move
four and semicon click tick and then
what we want to do now is go to an event
and in our step then we basically want
to compare our hit points to zero every
frame and if I hit point is equal to
zero
kill the object so we've already
discussed how to do with statements
before so I mean if HP open bracket
first HP equals zero equals equals zero
that's the comparative you should use
when your entry comparative value as
opposed that will work but you
specifically should use this
they could and like link an article in
the description that kind of explains
better as to what you should do that but
it's sort of a bit complicated for now
but if hitpoints is equal to zero
instance underscore destroy simple as
that now all we need to do is make it
sort of when our bullet collides with
our enemy the enemy loses hit points and
we destroy our ballot at the same time
so we probably want to do this inside
the bullet itself if we go to an event
in fact we won't use the collision event
here we'll just do it straight up in our
step event so that you can see a little
bit about how to code collision events
because that'll be a big thing in later
tutorials
okay so what we want to use here is a
thing called instance place us so if I
set this to all right if I say hit
equals instance underscore place open
bracket X Y object underscore enemy now
I don't want to explain what this means
on instance place is a special function
on the checks basically it will place a
virtual copy of the object that called
it so I'll place a virtual copy of our
bullet spring at the coordinates would
give it so I've just used x and y so
I'll place it at its own coordinates and
it will check those pixels the pixels of
your sprite at that position to see if
it overlaps with any object sprite that
you've put here so it'll check to see if
it hits that if it does it will return
the I to hit will become the ID of the
thing the the object that it found if it
doesn't find one of these it will simply
return a special variable called no one
so all we need to now is say if
it does not equal no one well that
simply means now is um if uh if it did
not equal no one that's what exclamation
mark equals means not equal it does not
equal no one that means we've hit
someone that means we've found an object
enemy that does overlap with our without
a bullet object so now what we need to
do is say hit which now as we know is
equal to that object
so hit dot HP which is a variable that
we set within the object - equals 174 so
now if we if we haven't hit nobody then
take the person that we hit reduce their
hit points by one and then we just need
to get rid of the bullet that we created
so instance destroy wrap your brackets
and go on and then let's try running
that so now if we shoot this guy as you
can see when they take four hits they
disappear
we've got no we messed up Oh what but
yeah as you can see me up I don't run
that any number of times now November
bah bah bah bah bah bah van that did
that did the dead and that's how you
kill those so that should give you now a
basic understanding of how to shoot at
things and make them die um all Sall to
different areas we could reach into from
there on enemies in terms of like making
them give up a little special effect
before they die or creating particles
and make them explode how to make a move
around different ways different ways
spawning them but while I consider what
the best air is to move into with that
what most people want to see with that
I'm leaving this tutorial of that so
that you can you know you basically you
get the basic idea and you know you're
encouraged to kind of explore and see
what you can change by
so because I mostly just want to teach
you sort of programming concepts and
stuff so that you can basically work out
in your own head okay I need to do this
thing so I need to set this alarm to be
this and I need to ask the game to check
whether or not I'm hitting this thing
and then if I can't do this thing and so
and so forth and you'll be able to
logically go through in your head you
know establish what the problem is
you're trying to solve and be able to
build it out of code yourself because
that's ultimately the goal of teaching
you how to use these things it's not
just to be able to teach you how to do
every situation you know you want to
ever create but to hopefully give you
enough key concepts so that eventually
you can do this kind of thing yourself
and like the help menu especially very
very very powerful shows you every
single like different line of code in
the game so if you if you're thinking I
wonder if there's like a line of code
that you know will will move my object
in a particular direction or something
like that you could just type in like
move be like move move towards you know
move to contact action and like lines of
code that are in here move towards point
for example on you you can find all this
kind of stuff in the whole menu well
that was a bit of a tangent I just went
off there but either way before we
finish this this particular tutorial on
on shooting enemies as you can see I've
just begun sort of meaning new turning
of the game a little bit in the
background as well creates a little
scrolling stars just using things we've
already covered in previous tutorials
you should be able to work out how to
how to make the star scroll
why done to create this color being a
little fake death kind of thing it's
just have two transparent backgrounds
and stars on them and simply made one
scroll slower than the other and that
creates this really really easy to fake
illusion of depth to your scene so
that's little thing I did I'll probably
include the GNX file of what I've done
all we've done so far just so you know
if you if you are having any problems
keeping a brain like that you can you
look through the code that I like
written for all of this stuff and then
you know go through it yourself and
compare it to the code you've written
work out any problems you might be
having so yeah that's that um and I will
see you next time guys have fun