Pygame (Python Game Development) Tutorial - 19 - Snake Length Rules Video Lecture | Pygame (Python Game Development): Create Awesome Games - Front-End Programming

what's going on everybody welcome to the
19th pygame tutorial video in this video
or what we're talking about is how we're
going to start molding our snake
function which is actually up here how
we can start molding our snake function
to handle the increasing length of our
snake whenever we run over an apple and
eat the apple so first of all we I guess
what I want to start with is the way
that we're going to draw the snake is by
drawing a bunch of different blocks
side-by-side that makes the snake and so
if the snake is say three segments long
you've got the snake head and then
you've got two other segments well the
location of those segments are just
direct copies of wherever that snakes
head was either one position ago or two
positions ago so what we want to do is
we just want to have a list and we want
the snake function to draw the snake
based on all the elements in that list
and then each time the snake moves we
just append a new location the X&Y
location that new location is appended
to that list
and if the list is longer than the
length of a snake then we delete one of
those little the most last day right the
last addition to that list so anyway
that's the idea so within our snake our
snake function really we have a few
things here obviously we have like snake
uh we've got lead X lead y and then
we've got block size well really what we
want to have here is we just need a
couple of things we just need block size
and then we need snake a snake list and
then in our function what we're going to
ask is for you've got sea snake and so
we'll say for uh we'll say x and y so
for x and y we're just kind of
specifying a variable for x and y in
snake list
so for each like element in snake list
and what snake list is going to be is
list of lists in each so each list in
the list is going to be a list of x and
y so like it'll be like 1 comma 2 and
then 3 comma 4 or something like that so
for x and y in snake list what do we
want to do well we tab this over and we
basically do pygame got draw it rect and
then instead of lead X lead Y the X
element will be the first one so it
would be X and y 0 and then this would
be X and y1 and that would draw um the
snake so we've got snake block size
snake list so now we have to actually
pass the snake list through our snake
functions so we'll come down to where
we're calling our snake function which
is here and again that what the element
are the things that we passed through
here are going to be a block underscore
size and then comma snake snake list and
now we have to kind of define some
variables to be snake list okay so first
we need snake list and that's going to
be an empty empty for now it's basically
what we're trying to do is we're trying
to copy the x and y because their snake
is getting longer yet so we just we just
really want this snake list
functionality to work first and then
we'll work on making the snake longer
and all of that so first snake list
empty list
um and then we've got the snake head
which you'll just be like where is the
head of the snake at the moment again
empty list now what we're going to say
is snake head dot append lead underscore
X so now we're referencing that lead X
variable and then snake head dot append
a lead underscore Y so now snake head is
a list of an X element in a Wyoming
now all we have to do is we need to do
snake list dot append um snake head so
snake
and now once you've done that we can
call a snake function and it's going to
run through block size and then the
snake list which in this case is always
going to be one long because we just
have the head and then we're clearing
the list every time because this this
definition of all this stuff is
occurring here in our while loop so one
that game x is so basically every time
we're clearing the list so we eventually
don't want to do that but we'll get
there in a little bit so anyways save
and run that and that's good no errors
yet so now we'll run around like this
cool so we're able to move the snake and
that's basically what we wanted to make
sure could happen is that we can move
the snake and things would work as
expected I cannot get this Apple there
we go so so some of that stuff might
have been somewhat confusing so I just
want to run through really quick one
last time what is happening here
so at the top here what we're doing is
we're expecting this snake list through
our function and then we're asking for
the elements in snake lists we could say
element here but I'm calling it X and y
because that's what it is it's a it's a
small - you know - element list which it
contains our X variable and a Y variable
and then we're just you we're
referencing them as 0 & 1 since the 0th
element in the list is the first element
and the 1 element is the second element
so this is our axis or Y as we're
drawing and then down here is where
we're actually finding those variables
so we've got snake head which really
snake list is only consisting of a snake
head right now because we're clearing
the list every single time but
eventually we'll have snake list up in
the game loop and it's only redefined
once in the game loop so when it's game
over it will be redefined but so then we
have snake list empty list snake head
empty list then we append X to the snake
head and then Y to the snake head and
then we append the snake head to snake
list so it's a list and a list now and
then we're drawing it updating it and
all that so anyway hopefully that's not
too confusing and now we're ready to
begin making our snake a little bit
longer each time and all that so it's
exciting so that's it for this tutorial
hope you guys enjoyed thank you for
watching