Android Application Development Tutorial - 170 - Rendering A Background

what's up guys welcome to your 170
eighth Android tutorial for the new boss
in and I know I told you guys we'd
render something last tutorial I kind of
forgot about it so just uh you know
we're gonna get into that in this
tutorial so again just to show you guys
a little bit more about these methods
and how we can use them we're gonna
render a few different times just to get
a better understanding of what's going
on and some of the methods that we can
use again all these methods have this GL
ten object that's being passed in all of
them are I'm sorry about that all of
them are pretty much the same and we can
relate to them and again like I said we
can set some specifics to them what we
want to handle like if we won't have
depth within our GL view and all that
stuff so let's just get into it
what we're gonna do first within our on
create method is type out our GL object
that's being passed in we're just gonna
say dot GL clear color and this is
basically saying hey when you call the
clear command or actually this is
basically just like setting the color
value for the most part but what what
this clear is all about you're probably
like what why is it calling it to clear
a color well basically all it's saying
is when you call the clear command you
know sending this message its home
what's up so what we're gonna do is
we're gonna paint our background or our
GL object that's being passed in and how
we do that is with four floats red value
green value blue value and an alpha
value so what we're gonna do is we're
just gonna say anywhere from zero to one
and let's give it a lot of red let's say
like 0.8 and we're just gonna say F for
float and for green we don't want any
green in there man green just isn't
gonna happen in blue what would that
make like purple oh we don't want him
well let's give it a little bit blue
like point to blue so again we can go
from 0 to 1 and for alpha we don't want
it to be transparent but so we're just
gonna set to 1
again you guys get if you want
transparency a little bit you can set
that zero if you I mean if you want a
lot of transparency set that to zero and
let's just uh call the clear method that
I was talking about so we actually get
to use this color thing we're gonna do
that within our on surface create just
for example we're just gonna really
again to our GL ten object and what
we're gonna do is say GL clear and it
takes a mask and what this mask is is
there's different buffers like there's a
buffer to handle the color there's a
buffer to handle the depth and stuff
like that so what we're gonna do is
we're gonna relate to our GL ten class
whoops
Jill ten we're just gonna say dot GL
underscore color buffer bit and that's
gonna handle basically our color buffer
and all that good stuff so let's run it
and see what happens and just you guys
are gonna have to watch real closely so
just make sure you take note we're gonna
run this and as you can see it flash
that red and that disappeared you're
like okay what was the point of that
well basically what's happening is we
call that within our on create method so
that's only gonna be called once right
when our activity starts and then we
have this draw frame thing so if we move
this clear command down into our draw
frame and run it again it should stay
because every time it calls this is
gonna be like hey I'm clearing the color
buffer or what color should I you know
you tell me what to do and then that's
what we set up within our on create
method so again let's run it and as you
can see it's just a solid red color
pretty good pretty awesome that's what
we want and we can also add like depth
so what we're gonna do is with them
again are on create method we're just
gonna say GL relating again to that GL
10 object and we're gonna say dot GL
clear again and this time we're gonna
say depth of a float and by default it's
gonna be one that's what we're gonna set
to I mean
is one and again now when we call our
clear command it's going to be like hey
set the depth to this so again right
here on our on draw method we're calling
the clear command but we have no
reference to any sort of death depth
buffer again there's different types of
buffers so we need to add that within
this clear command and how we do that is
again I don't know what that symbol is
it's just basically a straight line and
you just hit shift and it's the button
above your Enter key or your return key
so just throw one of those in there and
then again we're going to relate to our
GL 10 class dot GL underscore depth bit
our depth buffer bit and so now it's
gonna be like okay now I know what
buffer to you know clear with this
command here and that's what we're you
know it's always gonna be the same so
for the most part whatever we're gonna
just set our depth every time it calls
on on draw frame method and all that
good stuff so if for example you guys
wanted to make a random color you could
do that for homework or something but
you wouldn't want to do that within the
oncreate method because you know it's
not gonna be a random color so you'd
have to move this down within our on
draw method create some sort of a random
color like 1 3 or 0 through 1 or
something like that and you know set
that up and then your buffer or your
activity will just flash different
colors and so if you guys want some
homework just mess around with that but
that's for now that we aren't gonna go
too fast because I I've talked to a lot
of people and have trouble with OpenGL
but just some basic concepts here we set
the color and we set the depth and we
have to you call the clear command and
refer to the buffers that we want to
handle those so a pretty simple tutorial
but you know that's pretty much an
introduction to the renderer
we're gonna get into a lot more stuff
with surrender so don't worry about that
and I'll catch you guys in the next
tutorial have a good one