Android Application Development Tutorial - 183 - OpenGL Vertex Color Buffer Video Lecture | Android Application Development (Mobile App) - Software Development

what's up guys welcome to your 180 third
Android's tutorial for the new boss and
what we're gonna do is I told you guys
we'd get into tech tree and I was gonna
like print a bitmap on the triangle or
something like that but you know that'll
probably take up too much time and we've
been doing a lot of GL stuff or OpenGL
stuff so we're just gonna you know print
some colors on our triangle instead and
hopefully we can get everything done
within this tutorial so that's what
we're going to be doing we're gonna open
up our GL triangle class and we're going
to set up a new array that's gonna hold
our values for each vertex because our
each vertice here each vertice will have
a different color value they'll kind of
blend together you can see how that
works so what we're gonna do is we're
just going to copy this float here and
we're going to change this to our RGB a
for red green blue alpha values
something like that or just vowels and
obviously this is going to take four
values for each vertex a red value green
value blue value and an alpha value so
let's just try and a you know create
something so we're gonna have it be
completely red and completely green and
then no blue and maybe 0.5 for alpha so
half transparent for our first vert vert
to see man it's getting way too late
here and you know I don't really know
what color is these are gonna be I'm
always terrible with color so we're just
gonna kind of wing it and then next one
we're gonna say like a point two five F
for the red for the green we're gonna
have zero the blue we're gonna say like
0.85 something like that and then we'll
have a full alpha so it's completely
opaque instead of transparent and then
we also have to put F here I'm sorry
and then for last vertice let's say zero
one one and one as well so there we go
just basically our red green blue and
alpha values
and again we have to set up a buffer for
this so we're it's gonna be a float
buffer as well since we're working on
floats here we're just gonna call this
color buff and then what we're gonna do
is we're just gonna copy one of these
buffers down here because again we just
need a byte buffer as well pretty much
everything is the same except we're
going to change this from PB to just t4
like to c4 like color and also this one
to C and we also have to change this to
a float float buffer instead of a short
buffer and this to C as well and also we
need to you know get the length of our
new array that we set up here which we
called our GBA vowels so that's just
gonna get the length and we times that
by four cuz again their floats so I know
we're gonna kind of quick but this is
all kind of review for the most part and
then what we're gonna do is we're gonna
set up our a color buffer to be this
float buffer for all these as well so
again we're just gonna insert our colors
so it's RGB a valves there and then
we're just gonna you know move to
position zero and then we're good to go
now what we need to do is we need to go
within our ondraw method because this is
where you know we're actually gonna send
this is where we're actually gonna draw
our triangle and all that good stuff and
what we need to enable is the color
array so we're just gonna say GL GL see
if I can get it GL enable client state
and it's gonna refer to the again GL ten
dot GL underscore color array and then
we also have to disable this so we're
just gonna go below where we draw our
element and just say disabled client
state and again we're just gonna refer
the GL ten class dot GL underscore color
array and then we also have to set up a
pointer for our color for our colors for
each vertex and all that good stuff so
right below
are right above our draw elements and
blow our vertex pointer we're just gonna
say GL dot GL color pointer down here
and again it takes a size so the size is
going to be how many dimensions were
working with since we have a red value a
green value of blue value an alpha value
there's four dimensions or four things
within per line that it's looking for
the type again is a float so we're just
gonna say a GL 10 dot GL underscore
float and the stride with zero and the
pointer is the pointer that we set up
called color buff and there we go let's
just try and run it hopefully everything
works I don't think we need to set up
anything within a renderer class so yeah
a renderer class should be fine we don't
have to change anything there and there
we go we have this crazy-looking
triangle with different colors for each
one and that's pretty much it for the
opengl stuff i know we went kind of
quick through the colors here but
hopefully you know it's kind of a
repetitious enough where you understand
what these buffers are doing how to set
them up again all we had to do is we had
to enable the color array and disabled
as well and then we also set our pointer
and you know that's pretty much it for
these tutorials and we're gonna move on
to something you know not as complex
just like some small tutorials like one
or two tutorials to complete whatever
we're trying to do and then you know
we're gonna be pretty much done here
soon so thanks again for watching guys
and I'll catch you in the next tutorial
have a good one