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| Title:
Low Polygon
Hair Texturing |
| Artist: Ben
Mathis |
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Low
poly hair is the bane of most game artists
existence. Rarely is it done well, and
the majority of the time, a bald head,
or a slicked back look is taken as the
easy way out. For three months I was
in charge of creating the various hairstyles
for Dark Age of Camelots: Catacombs
expansion. Making the characters bald
was not an option, so I set out trying
to figure the best way to create low
polygon count, heavily textured hair.
Examples of my results can be seen here.
The PSD of the final hair texture created
in this tutorial is here.
First
you need to set up your arsenal, your
tool set. I used a few custom brushes
for this. Credit for the idea, goes
to Adobe with their hair tutorial. To
create a brush, make a new canvas roughly
the size of the brush you want. Create
a black and white image, and go to Edit>
Define Brush. The black areas will be
the brush bristles, and the White areas
will be transparent. You will also need
to lower the spacing, and have your
tablet pressure control the opacity
of the hair. It works best to have it
stay at a constant size, so do not let
pressure control size. Here are my brushes
(note that the last one is just a one
pixel brush set to hard, no need to
create that). Each is being displayed
four times their actual resolution.
You can actually drag these into Photoshop
and just click edit>define brush,
or you can download my set here.
I encourage you to make your own and
play around with the settings.
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The
first brush is for soft hair like fill.
It works at different sizes, and it
is fairly soft. The second is for adding
a bit of sharpness and definition over
top of the first. It should be used
in quick strokes. The second and third
are double hairs, used either horizontally
or vertically, and can come in handy
when the three hair brush is too much.
The final is a single pixel brush set
to hard, and is for precision placement
when things just need a little touching
up.
I
contemplated doing an entire head, but
each approach is specific to the hairstyle
you are wanting to do. I can not do
all the leg work for you, and figuring
new ways to use old techniques is one
of a Game artists greatest abilities.
So I will be only showing you a small
example of creating hair, but hopefully
you will be able to extrapolate out
how to tackle your specific problem.
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Reference is KEY! |
Always
find reference of the color and rough
style you want. then make a few rough
drawings of the style you are going
after. The less seams you can keep while
creating your hair, the better. Its
all about the quick uninterupted strokes.
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First
thing I do is pick a nice base color,
normally this is fairly dark, as I tend
to lighten things as I go. |
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Using
the soft hair brush, I rough out a general
flow of the hair. Lighter at the top,
and darker at the bottom. Keep the root
area (top) darker as well. |
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Now
I try to pick out a few shapes to make
it not just straight hair. Clump it together
in a few spots, and make it deep in a
few others. Every so often, I change the
brush from normal mode, to soft light
mode, in order to get some color variation
in. |
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I
used the three pixel hard hairbrush to
go in and add some more fine detail. Keep
in mind, you can and should use these
brushes in both brush mode and smudge
mode. Set pressure to control strength,
and pick these brush shapes for your smudge
tool. The lower resolution your hair is,
the more you will need to smudge. At this
resolution, a single pixel is fine for
a hairs width, but in a much smaller space,
a single pixel will be too large and will
make the hair look like yarn. So smudging
will keep the hair-ness look there. |
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Make
a selection over the areas that the highlights
should go using the polygonal lasso tool.
Hit ctrl+alt+D for the feather option,
and pick a feather size appropriate for
your texture. On mine I am going to use
a value of 5 |
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I
used the three pixel hard hairbrush with
a much lighter color to go in and add
the initial specular. By making a selection
and feathering it, you can use very fast
and very sharp strokes, with perfect fading
in and out. Hair specular is unique. Hairs
are translucent, so not only do they shine,
but they transmit that shine up and down
the shaft of the hair. There is normally
a base specular, which is the absorbed
light. That is what I painted in this
step. This highlight tends to be saturated
the color of the hair. |
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Make
another selection, this time smaller,
and put it about the two thirds of the
way up of the previous highlight area.
Feather this a smaller amount, I used
a value of 1.5. |
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I
highlighted within this area, then deselected,
and cleaned up in some other areas, using
the two pixel vertical hairbrush. I took
some redder colors and blended the highlights
into the lower parts. This is the primary
specular, and it is actually the hair
reflecting the light source. It tends
to be cooler and closer to white. |
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No
hair is complete without some scalp showing.
I cant think of many hairstyles where
you would not see at least some scalp.
I like to always show the scalp at the
crown of the head where all the hair grows
from, as well as any split going down
the center. This is merely a new layer,
filled totally with skin color. I applied
a mask, and painted on the mask to reveal
the skin. This is important because of
the next step, to have it on its own later,
and a mask revealing it. |
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Add
a layer effect to this layer. Inner shadow,
change the color to a dark skin color
like a deep orange red. Keep the inner
shadow set to multiply, and decrease the
distance to zero, and the size to 1 or
2. This makes it look like the hairs are
shadowing the scalp, and you can paint
on your actual layer to show the roundess
of the scalp, because all the hair shadowing
comes from the layer effects. |
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This
is a PIMM original technique. It just
came to me while thinking about what makes
most painted hair so fake. Real hair breaks,
and the shorter pieces will tend to stick
out. To simulate this, grab the three
pixel brush or the one pixel, and change
the opacity controls from pressure, to
"fade" play with the number of steps,
I use between 15-45 depending on the size
of the texture. This will force the stroke
to start at full opacity and fade to zero
over that many steps. Now brush into
the direction of the hair. This simulates
the broken edes of the hair. I normally
do this on a new layer, and then play
with the opacity of the layer before flattening.
Use both light and dark strokes, and it
will help make the hair look more realistic.
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Create
a new layer set to softlight mode. Using
your soft hairbrush, and a dark and light
color (pick them appropriate to your hair
style color) go in and reinforce the depth
of those clumps you made earlier. This
will help the hair read from further away
in the game. The dark bits will make the
hair seem like it has more of a sheen
to it. |
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Now
for tricks on making your 3D hair better.
The hair looks good as is, but its kind
of flat and lifeless, lets fix that. This
is assuming you only have 1bit alpha,
but it will work just as well if you have
8bit alpha. In fact it will look better
if you do. |
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Here
is my alpha mask for the hair. When you
are painting in the alpha channel, hit
"~" to get the color image overlayed on
the alpha. Hit it again to go back to
seeing the alpha channel only. |
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You
can see the edge of the hair looks much
nicer with the alpha map. Now comes the
fun part, making the hair more volumetric.
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Shift
click these faces, and select "clone to
element". Now convert your face selection
to vertices, by ctrl clicking on the vertices
element on the right control panel. (this
is all max specific) |
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Now
convert your face selection to vertices,
by ctrl clicking on the vertices element
on the right control panel. (this is all
max specific) Now subtract the top three
verts from the selection, so that you
can move just the bottom six. this will
make it look like the hair all stems from
the same place. This makes the hair look
thicker because as the model moves, you
will see the inner plane move behind the
outer plane. This parralax will make the
hair seem much more voluminous than it
is, and helps to kill the plane illusion.
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I
did this again at the tip, with the bottom
two planes. What can enhance the illusion
even more, is to darken the under planes
using vertex lighting if you have that
available. Or you can flip the uvs so
that you cannot see the mirroring of the
texture from one layer down to the next.
be sure to ofset them both in length,
as well as slide them a bit to one side
or the other, for a more random hair look.
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I
added one more flip outwards with a single
plane. Here you can see what it will look
like in a game with the wireframe turned
off. |
Closing
Points:
Create
the initial volume quickly with the
soft brush. It is very forgiving, and
will give a rough hairlike look right
away. Do not move past this stage until
the hair reads as a volume from far
away. Move on to picking out individual
clumps next, so that the hair reads
as fibers at any distance. Next use
the sharper brushes to detail the hair
a bit so that it looks nice from up
close. Use soft light layers to enhance
the sheen look, and deepen the volume
whenever you need to. Use the smudge
brush with these hairbrushes to blend.
Add random tips if your resolution allows
it. Use multiple planes to enhance the
volume of the hair. Use alpha maps when
possible to soften the edges of the
hair. Use Lasso selections with a bit
of feathering for highlights. Have fun,
and explore new techniques!
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