Blender 2.7 Tutorial #44 : Sky Color vs Sky Light (Light Path node) #b3d Video Lecture | Learn and Master: Blender (English) - Professional Skills

hello and welcome our 44 video shooters
aunty's wonder 2.7 in this video we're
here looking at sky color versus sky
light
alright so let's go ahead and dive in
I'll click on the splash screen to get
rid of it and the first thing we could
do is change our render engine if you
haven't already from the blender render
engine up here down to the cycles render
engine one of the cool features of the
cycles render engine is that you get
light for free so the first thing I'll
do is I'll select the light in my scene
and I'll press X on my keyboard and
delete it the reason I can do that is
because if I go and switch my viewport
shading mode over to rendered you can
see that I can still see my cube even
though there is no light in my scene and
the reason why that's happening is
because the world the material of the
world is actually projecting light in
the color that the world is so right now
the world is this great color and it's
projecting that gray light on the scene
making my cube gray how do I change that
well over here in the properties window
under the world tab I can change the
surface color right here now we're going
to get into nodes in a sec but if I
click on this block right there I can
choose the color I can turn up the
brightness as you can see that's also
changing the color of the cube if I
change the color of the light let's say
I want to make the light a little bit
blue to emulate outside I'll click up
here on the blue area and the cube also
becomes blue now let's take a step back
I want to set up a really simple scene
so I'll go back into my solve you and
I'll press shift a and I'll add a new
plane mesh and I'll press s and 10 to
scale it up 10 times and I think I'll
grab my cube and press G and then Z and
then one move it up one unit on the z
axis and I'll press ENTER so now I've
got our really really simple scene I've
got a cube on a ground and let's say I
want my sky color which I still have up
here in the properties window I want to
be a nice sky-blue color so I'll click
on the color box and I'll make it you
know nice guy blue and let's take a look
at my scene well right now we have no
materials on anything and that's ok
we'll add some in a minute
let's go ahead and change our viewport
shading back down into render display
mode well wait a sec I have a white or
almost white floor and almost
y/q why is everything becoming blue well
that's one of the features of blender
the fact that your world color the way
that you see it shines that color of
light onto everything
that might be a problem now you can add
more lights if I were to press shift a
here and add a lamp and I might add a
area lamp and I'll press G and Z to move
it straight up I can get white light in
my scene but what if I want my sky color
to be this nice blue color but not have
it project that color of light onto my
scene what if I just want to have no
lamp so with my lamp still selected I'll
press X on my keyboard what if I want my
seem to be lit with white light or any
other code that I choose and not this
really intense blue in order to keep
everything the color that I want to be
well to do that we're going to be using
a light paths node now that's not scary
don't worry it's not the first thing
we're going to do is click on this use
nodes button under the world tab in the
surface area of the properties window so
click on use notes then I'll drag this
little crosshatch area down because I
want a second window yep we need our
nodes editor window up so I'll drag that
area down and I'll change this window
type from 3d viewport down here on my
header to a node editor window now right
now I just nothing in it and the reason
why that is because well we have nothing
selected and right now the node enter
window thinks that we're working with
objects
if I select let's say that cube and I go
over to the materials tab I can click on
use nodes and I can give that material a
color right here in fact I'm going to
give my ground object which I need to
add a material to I'm going to give it a
green color and by default when you add
a new material in cycles it uses notes
so I'll click here and I'll select green
so now we have a nice green color for
the grass but it's being influenced by
that blue color so it's not looking like
the color that I want how do I see the
nodes for the world well that option is
right here on the header of the node
editor window right now we're working
with nodes only for objects but I can
switch over to nodes for the world
material and as you can see here I have
a background cheater for the world color
and it's not the same as a diffuse color
it's not same as in a mid color or
shader it's actually a special
background material or shader just like
any object it has an output in this case
it's world output so what we're going to
do here is we're going to add a few more
nodes we're going to add two different
background colors one that's going to be
affecting everything else in the scene
in other words what color of light
projects and the other will be how we
see it so right now I'm going to leave
this one the way it is but I'll press
shift a on my keyboard now I'm going to
add a new shader and a background
chatter so I'll click on background
shader and then I'll click and put it
right below my other background shader
and I'm actually going to have to
combine these two with a mix shader' now
if you have no idea what I'm talking
about because you haven't seen notes
before I actually made a beginner video
on notes so if you never use the Cycles
render engine with nodes I'll put a link
to that on the screen right now let's go
ahead and add a mix aider so I'll press
shift a and I'm going to select shader
and mix shader'
and I'll click there and I drag it so
sort of in between the output and these
two background shaders and I'll put it
right on that one to connect it
automatically now when it does that it
gives it a factor and that's because
it's using only 50% of this value along
with right now black because this one
has no input what a mixer does is it
basically takes the two inputs and it
blends them together by a different
factor if I turn the factor all the way
up to one it uses only the bottom slot
if I turn it down to zero it only uses
the top slot so I'm going to go ahead
and plug the white or almost white color
in fact I'll turn it all the way up to
white I'll grab this node plug and drag
it into that one so now if I drag factor
up to one we get a white sky but that's
not what I want I want it to be a blue
sky plugin a drag it straight down now
the way that you make the light on the
scene different than the color of the
background is we have to use a light
paths nodes let's go ahead in our node
editor window and press shift a and I'm
going to select input and light paths
now this is a really really powerful
node it basically allows you to control
the way that light bounces in your scene
relative to other objects you can see
there's a ton of options here and I'm
only gonna touch about one in this very
introductory but
you on this note but what I'll do here
is I'm going to use the is camera ray
output so I'll take that output and drag
it into the factor and now what you can
see I'm not going to do a little bit of
organizing here what you can see here is
that is taking only this bottom color so
what I'll actually do here is I'll
switch these two around I'll just drag
the input up to this one and they'll
automatically switch and it'll organize
these a little bit better what it's
doing is it's only taking the light from
the upper input upper material and it's
projecting that color of light onto the
scene so right now our white cube is
pretty well white us because that's the
light color it's receiving but the sky
color is the bottom color so that's how
you use the light paths node to have a
different color light than your sky
color all right so now in our scene we
have light light with a blue background
and that's great but what about this
white cube here why is it green well the
way the cycles render engine works and
the way that light actually bounces in
the real world is when light bounces off
of an object with one strong color and
something else is very near to it the
light of that color will actually bounce
onto that second object so as you can
see we have an almost white cube that's
getting a lot of green especially on its
sides from the very green ground how do
we stop that well do that we're also
going to use the light paths node we're
going to use one more different output
that is diffuse ray output so I'm going
to switch back into my material notes
with this little button right here and
I'm going to select the ground now it is
actually selected and I might go back
into material viewport shading just so
we can see the object without the actual
light now again here we're going to have
to space our nodes out of this material
to add in a mixed shader and a second
node and a light passed note so I'll
quickly do that shift a I'm going to add
a shader it's going to be a mixture I'll
drag that into that noodle right there
I'm going to press shift a and we're
going to add another diffuse shader
remember that's an object so we're not
using background I'll drag it up there
and I'll connect this noodle with the
white color almost wet color into the
bottom input of this shader and I'll
change this material color to total
only white let's go ahead and add that
same light Pat's note so I'll press
shift a and it is in input and light
path
so I'll click and place it and then this
time I'm going to drag the is diffuse
ray option into the factor now when you
do this just like last time
this is diffuse ray option actually
takes over the factor so you no longer
get the slider but let's go ahead and
check out what this looks like now in
rendered viewport shading mode so I'll
go down here I'll change our viewport
shading to rendered and as you can see
now even though we have a green ground
and a white skylight that diffuse color
is not bouncing up onto the cubes let's
another use for the light path node
there are a lot more options for it but
that'll be a fence for you thanks for
watching and I'll see you next time