C++ Allegro 5 Made Easy Tutorial 31 - Split Screen Multiplayer [Camera Effects] Video Lecture | Allegro: A Complete Guide - Game Development

hello everybody and welcome to your next
C++ Lego 5 tutorial and this tutorial
we're going to be learning on how to do
split-screen so if you want to have two
different people playing on the same
screen etc etc this is a good tutorial
for you and even if you don't plan on
utilizing this anytime in the future I
think this tutorial be it should be
beneficial to you because it's
jam-packed with a lot of different
concepts and it could kind of enlighten
you and help you think outside the box
cetera et cetera so if this is gonna be
oh this is gonna be it's not gonna be
it's gonna be more complicated in the
other tutorials but I hope it's not too
too complicated to understand so right
now we have two strokes and/or data
structures or whatever you want to call
them and the ones called plan ones
called camera now if you're familiar
with classes then this is kind of like
similar but it's not in the it's kind of
the same format of a class but it's
simpler
so we ever struck top layer and these
are the things inside of it the
variables inside of it have another
struct called camera and these are the
variables inside of it now I don't have
time to really go in depth on watch
structure so if you don't know them then
I search it up on the internet but yeah
so our for our camera update since we're
doing split-screen the weather screen is
gonna be the screamo divided by 2
divided by 2 so then therefore it's
going to be there for the camera for the
rotation the center of the screen my
dad's gonna be screen width divided by 2
divided by 2 so just add that in there
so once we get into our main function we
have our degrees in our scale we have
and then we have a new variable called
toggle and that's gonna be able to
toggle between the two players that were
controlling ok so right now we have our
player that we load in we have our
background image
how much have a divider to show the
dividing between each two screens and
then oh we have a bitmap we have a
bitmap called screens with two elements
in there so this is gonna represent the
first screen for the first player and
and second elements cannot present the
second screen for the second player so
the key state you should be familiar
with ok so now I'm creating two
instances of the player structure so we
made them in an array of two and we made
the camera an array of two as well so
then we have our defaults or variables
like before XY move speed camera
position Direction active and we have a
new variable called player number I'm
gonna set it to 0 so that is the active
play that were moving or or doing
effects for at the moment so now we have
a for loop that loop start till 2
our toast less than 2 and we just
basically initialize the basic stuff for
each of these structures so we just put
a default values in there
after that we clear our timers all the
event cubes that's from last tutorial so
nothing new there we start the timer
have our event wait for events set up
cetera and then we have a new event
right here so we will put elsif event
type Allegro vent key down so if they
pressure down key and the key is a tee
button then we set toggle equals our
true okay so when toggle to go to true
then we're gonna toggle between the
different players so I will go back to
that later
but in our in our update and update
timer we have first of all we set our x
value original X is equals to the player
player numbers X and our Y is equal to
the current players Y position and
directions equal to the current players
direction and degrees is equals to the
current cameras degrees and the skills
equal to the current
rescale okay so this stuff is familiar
this stuff is the same as last tutorial
so we can scroll down so after that we
just set we set our x equal to the
modified value from here and then we
said all the modified values into our
into an active player so as for the
degrees in the scale that should be
familiar to you and then after that we
just said we set the new value into our
degrees variable and our scale variable
so after that now we got to our toggle
so if toggles equals is true then we set
player number to equal 1 or 0 okay so
what does this thing right now this is
kind of looking if or else statement so
we say that if player is equal to player
now if player numbers equal to 0 then we
set it to 1 if it's not equal to 0 then
we said it's a 0 that's what basically
saying and if you want you could set
player number to a boolean variable
since boolean since false represent us
plus since false equal to 0 and to 0 to
1 you could have because you cannot
player number as a boolean type and you
could say that if but you could just say
player number is equal to not player
number so therefore player number is
equal to false for the default value say
it's equal to false then it would change
the true and then if it's true the no
change it to false so you can do that
either way you could have it as a
boolean or a regular number since we're
only scrolling through two values it's
really up to you and after that we said
Todd will equal defaults so after after
we said we set our player number what
we're gonna do is now we have to set our
our transforms and and such so first of
all we set our current position equal to
the cameras current x and y position and
we put it into our camera update right
so that I'll update the counts position
and then we set the new value into our
camera accent on camera why okay so we
haven't enough for loop right here so we
say the identity is equal to ampersand
the camera eye that transform and we do
we scroll to all of this and and all the
values I have to just replace it with is
for the camera position for the
transform you just put the cameras
transform variable and for the players X
you just put player I dot X whatever etc
etc for the current player and
everything for the current camera
everything should be I set right there
and if you want you can pause the video
right now and copy it or you can
download this source code off the
website it should be up shortly after I
post this to YouTube so if you want you
can download social cause off my website
according minis ETA so anyways we set
this up but notice we don't have a I'll
use transform that will come later so we
set up we set up our transform but we
never did anything yet and for the for
the source for the frame timer we just
changed the player number source etc etc
and yeah we change everything to the
current player so if we go toward draw
now we set our bitmap to submit map so
what we need to do is that we need to
set our target let's set our bitmap
target so we know what you've been up
word we're drawing two so I'm not sure
if ice I mentioned this is my other
tutorials I'm not really sure but a set
bitmap set target bitmap basically it
sets of what we're we're gonna be
drawing to so by default we draw to the
display to the back buffer but in this
we're changing where we're drawing our
image to and I believe me I did I
believe I actually did explain that but
so then we say that I'll set target
bitmap we set it to the this current
screen that were drawing to and we said
sub bitmap equal to the current player
we said all the defaults you should be
this should be familiar to you and after
we say ALU transform and then we
transform according to the current
camera where the camera the player that
players camera then we clear the color
the color of our bitmap we draw the
background and then we draw our current
player and we also want to draw the
other player to the screen as well
so we're going to say that if I is equal
to 1 then we know that the net the
second player is going to be equal to a
player one right a player and then the
bracket is gonna be 1 or if if I is
equal to 1 then we know that the other
players are gonna be player Brett the
player in the index 0 so we basically
you sub bitmap we get all the
information from that player and then we
draw that player to the to that players
current position on the screen and we do
that like so so after we've drawn that
and we set the target bitmap back to the
display so we do that by saying I'll get
back buffer and we put in the display in
there and then after we do that it will
display it will set it back to so that
we can draw everything to our display so
then it will what would what would
accent we've already done that now we
need to just draw our bitmaps or our two
separate screens to the screen so our
first player screen is gonna be towards
the left of the screen so we we set our
bitmap we draw that coordinate in 0 0
for our second player is gonna be it's
gonna start at the halfway point of the
screen so we say we draw screens 1 and
then we draw it we start drawing at
screen with divided by 2 and in the y
coordinate at 0 okay and after we draw
the divider two divided two screens and
we flip the display clear the color and
then we destroyed the sub bitmap since
we created within this draw function and
then we have the rest of our destroy
functions and stuff right here so
everything should be good so if we run
this program just to see what we get
so on our screen we see that player
player on the left and the right so
right now I'm moving the it's the player
on the Left right so if you if you look
on the on the right overheads the player
two's view and this is the player ones
of you so if I scroll right here notice
that this screen is centered on this
player right because the player one view
and notice that the players off is off
to the side of the screen now cuz in the
players to you were focused on this
player we're not focus on player one
will only focus on player two so the
players to view is out of view but in
the players 1 viewport we see our player
clearly right and it comes back right
and if I click T to toggle to the next
player then we see that is focused on
the second player in this view and it's
focused on still focus on the first
player in this view so we can see a move
and if we zoom in so we zoom in to the
second player and we talk back to the
first player everything is still fine in
the first place world but when we look
on the second player screen it looks
zoomed in because it's based on what the
second player sees now with the first
player sees so yeah so that is it for
this tutorial I hope you enjoyed it
thanks for watching and bye