C# Xna Made Easy Tutorial 25 - Bounding Box Collision Video Lecture | C# Game Development: Game Making made Easy (English)

hello everybody and welcome to my next a
c-sharp XNA tutorial so in this tutorial
we're going to be learning about an
advanced will not advance subject but a
really important subject called bounding
box collision and what bounding box
collision is its collision between two
different rectangular areas okay so
bounding box collision if you want to
know is the most common type of
collision in 2d games all 2d games or
most so majority of them involve
collision and most of them have done in
box collision there are indeed other
types of collision like pixel collision
or a circular collision but bounding box
collision is the most common the most
accurate is pixel collision but it
requires a lot from the hardware and
only should be used in in situations
when there are like explicitly
explicitly needed okay but in this
tutorial I'm gonna be showing you the
regular method of handling bounding box
collision and the XNA way of handling it
or like I call the easy way so let us
get into it so basically an overview of
the code I have right now I basically
have two sprites the position for the
player sprite the key state so I can
actually move the player now the color
of the player so when we collide with
the enemy the player is gonna change
color and the move speed of the player
so in the load content this both the
player and the enemy spray or come from
the same sprite all I'm going to do is
just change the color of them and then
the updates we get the key States with
the gate the keyboard state sorry we
check for all directions I mean alter
the position accordingly and then we
draw the player according to the
position our position vector and our
players color let me draw the enemy at
the coordinate 100 100 and this color is
black or we tint it to the color black
so how are we gonna handle bounding box
collision so first of all let's go to
pay
Anette so first of all what we want to
check is for not collision for non
collision so what we want to do is a
check of the player is to the left of
the enemy therefore there's no collision
if the players to the right of the enemy
and I know you can't see the other side
of the box but the first at the right
side of the enemy
there's no collision if it's above the
enemy
there's no collision and if it's below
the enemy there's no collision what if
it is touching it then there is a
collision and we're going to figure out
how to do that using this code right
here so what we're going to do is we're
going to put if position dot X plus
bright one that is our actual player so
Spray one dot with it's less than a
hundred I remember a hunt on the plate
the enemy's position is out the corner
at 100 100 so this is saying if the
players to the left of the enemy and
then we check to see if the player is to
the right of the enemy so 4 is greater
than sprite 2 dot width and then now we
have to check if the enemy as the
players above the enemy so player a
hundred-plus right to that width so we
do player position y plus sprite one dot
height this time is less than 100 cut up
the enemy's Y position that corner in
100 and then we do this for the at the
players below the enemy so player is
greater than sprite and 2 dot height
okay so if it is not touching the enemy
then there is no collision and if
there's no collision then we're going to
change the players we're gonna keep the
players color a color white else there
is a collision and then we're gonna
change the color to color dot turquoise
the reason why I choose turquoise is
because if you tint it to a different
color it might not always tend to you
might not actually see much of a distant
difference so when I tended to a
turquoise color the player will the
players red right now by default and
look at kind of brownish color one tree
tinted so let's run this program now to
see what we get so if the player towards
the enemy noticed that the players color
changes to a brownish color okay so that
is bounding box collision so if you want
to use that the code from the sprite
animation tutorial or whatever you can
say that if it collides you can
calculate the direction so say you have
like direction or like say say you're
calculating if it's facing down or
whatever when you're doing your current
frame so you could save like current
frame equals sit down or whatever and it
collides or something then therefore and
then therefore you could say that the
player doesn't move anymore or the
player y subtract equals blah blah blah
whatever for closet a wall or something
if you don't want a player to move
through the wall etc etc so there's
different things you can do if there's
not a collision or if there is a
collision and this method is to help you
handle it and you can put all this stuff
in a method if you want so if you want
to like have a private method and then
you would in the in the parameters you
have like you get the player's position
or you could get a vector sorry you
could get a vector to player and you
could get a vector to enemy's position
and then what you would do is to like
player dot X whatever blah blah blah and
you're not to get the players with
whatever you could do a vector to done
player dimensions etc etc and you could
you could do that to a method if you
like because most like you're gonna be
doing it through a method or something
so if you want to put it in a method
it's up to you how you want to handle it
but yeah so that's one method to handle
it and this is the X name or the easy
way now
just because we use XNA doesn't mean we
always use the X in a way if you don't
know how to do bounding box collision
this way then learn it do not use the
way I'm about to show you
now learn this method first and then use
it easier later because when using
different api's different api's aren't
gonna have the functionality or might
not have the functionality that we're
gonna use right here or you're gonna
have to make that functionality by
yourself which you're probably not gonna
want to do so learn this method right
here first which is the proper way to
handle it and then we're gonna learn the
other use the other way once you gain
experience with this method so I'm gonna
comment this out right now and what
we're gonna do is we're going to create
two rectangles okay so one rectangle is
gonna represent the player and one's
gonna represent the enemy
okay so player 1 or I'll just put player
and enemy okay so uh under base
initialize we're gonna put enemy new
rectangle the player's coordinates 100
by 100 and the I mean the the enemies
with sprite to that width and sprite to
that height and why do I say under
initialize once the initialize is called
a cause D load content method as well so
therefore it will load these sprites it
will load the the player and the enemy
sprites and therefore it will have the
it will have the property store like the
width and the height if we do this above
the based I'll initialize and therefore
it's not gonna know what the sprites
width and height is yet because it
hasn't loaded it yet and therefore
you'll run into a compiler a runtime
error so you might be saying why not do
this and the load content method or
whatever you can do it if you want but I
believe since we're initializing
something should go in the initialize
method but whatever suits your needs
it's up to you so the reason why I'm not
putting the player 1 and there is
because the player moves every single
update or you can move the player every
single update and therefore the
rectangle might change every cell might
change during the certain update the
enemy position is static and there's no
point in putting this in the update
method if it's going to remain static
there's not going to move that
there's no point of trying to do new
rectangle every single time of all the
parameters are gonna remain the same
it's not gonna affect our productivity
of our program
it's just comment it's good programming
practice and larger programs one space
is critical you're gonna want to
minimize or like when the functionality
or speed is critical you're not gonna
want to update something that does not
need to be updated so this is just a
good programming practice so anyways in
our updates and our update method after
we've altered our players position after
the keyboard stuff when I put players
equal to new rectangle so remember
there's a Casa to an integer sense
position is of the float type of other
float type in the right tango needs to
be an integer type so we do position Y
and we need to get this sprite one sorry
right one dot width and sprite one dot
height and I'm not sure you can actually
see that so so yeah you get the sprite
one dot height okay and we store right
there and so I think somebody in one of
my earlier videos was asking if the
rectangle can contain floats and stuff
like that or for the sprite animation I
never really looked into that but I
don't believe that you could take float
values so you'd have to alter it to do
your own way if you wanna take and float
values for whatever reason okay but so
then we stored our players rectangle
there so what we're gonna do is I want
to do a player dot intersects intersects
and then we say enemy so if our player
collides with the enemy or intersects
with the enemy therefore there's a
collision so we do player colors equal
to color dark turquoise and else if
there's no collision then we just said
the player's color equal to white so
this is self-explanatory if they collide
if you intersects the enemies rectangle
area then therefore the collision of
house and then we just making the same
color so I'm gonna run it one more time
and we should get the exact same thing
exact same result it turns brown let me
touch it so that is it for this tutorial
hope you enjoyed it thanks for watching
and bye