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Update(10,Dec)
Since some people have emailed me for
explainations, I have decided to added
a sample file for this tutorial get
it here, it shows the basic concept
at work.
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..::[Intro]::..
Creating cg hair
in 3D is a difficult task, the most
common approach uses geometry surface
with texture mapping. There are a few
disadvantages to this method, that makes
it difficult to work with. First of
all to to tweak the look of your hair
requires repainting texture maps, and
to control the form requires careful
planing and placing each geometry piece.So
why Paint Effects? Pfx is a very effective
tool suited for creating hair, it gives
you ultimate control on exactly how
you shape your hair, with no texture
painting/alpha maps and lesser time
to setup. Changing the looks of your
hair can be done on the fly with instant
feed back. It is very faster to render,
takes very little memory. The render
that appears on the above image will
take no more than 30 seconds on a 1Ghz
machine. "Did you say 30sec!?"
"Yes I did", "But I heard
in the Final Fantasy Movie it took ..xxxxx
amount of days with xxxx machines and
xxx mount of people...." Haha...I
was only joking this is nothing compare
to FF of course, but with performance(speed)
to quality ratio, Paint Effects can
prove very effective, just read on and
I shall you how.
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..::[Part1
setup ]::..
First you'll
need to have a clear vision of what
kind of hair you want for your character,
otherwise you'll find your self tweaking
endlessly in Maya without any satisfaction.
If the image of the hair you want
is not in your head then its best
to work against a image plane of a
photo or sketch. OK so you have a
head of some character, we need to
make that surface live
and draw curves on top of the skull.
If you have a subd surface just convert
to poly for makelive. Select the head,
Modify->Make Live ,
Create->CV curve tool, start from
the back and middle of the head to
the front. This curve determines where
the hair splits, check my reference
for how long this should be. Now EditCurves->Rebuild
curve , rebuilt it to uniform and
around 9 spans, degree 3. You should
also turn on show CV for the curve,
you are going to need this often in
this tut. You should assign
this command to a hotkey,like Cntrl-Alt-V,
rename this curve to hair_split_curve01.
Now select the curve, Duplicate then
move the two
curves apart a little so that mid
line of the head is in between the
two curves(below)rename the second
curve hair_split_curve02. Also draw
a small curve between at the front
of these two hair_split curves, so
they join. Doesn't have to be too
accurate, 2 spans should do(below).
Lower and scale these 3 curves so
they are borrowed inside the head.
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..::[Part2
hair control curves]::..
We are going
to draw a series of curves that roughly
resembles how the hair should flow.
Select the head, Make Live, CV curve
tool, start off by snapping the first
point on to the front CV of hair_split_curve01.
Then place about 4-6 CVs on the side
of the head(left). The number of CV
should be as little as possible while
still able to give enough control
to shape your hair later on. You can
start off a bit more and then delete
the CVs later on if the controls takes
too long to tweak. Continuously place
new curves this way snapping the start
of the each new curve to the CVs on
the hair_split_curve01. This way the
main hair_control_curve are evenly
spread, and will result better optimization
for paintfx later on. If your
hair_split_curve01 has 9 spans you
should end up drawing 9 to 11 hair_control_curves
on one side of the head. Now select
first hair_control_curve and move
the CVs out from the head, so they
don't
intersect with the head.Tweak the
CVs on this curve so they take the
shape of your hair in that region.(i.e.
front, side). Now tweak all the CVs
of the hair_control_curves, so they
don't intersect and take on the shape
of your hair. Take your time, the
better resemblance of your hair you
achieve here with few curves/CVs the
better look/optimized paintfx will
perform later on. I' would say spending
a good 30min tweaking will be while
worth it :) check the images below
for reference.After tweaking them
Group the hair_control_curves and
Duplicate to the other side Then tweak
a little to make the difference between
the two sides. Now draw the curves
the same way for the front hair_split_curve,
so that you have a some hair control
curves for the front. 3 curves would
be
good, make sure those curves looks
continuous to the curves control curves
on the left and right side.(More below)
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..::[Part3
Power of Pfx]::..
Now we are ready
to make some hair! Go to the visor
and open up the *brushes/hair/ folder
and select a hair brush that mostly
resembles your
hair design. If you have followed
my hair design then select the hairRed1.mel(right,
make sure its highlighted). We are
going to base on this brush to start
off, select hair_split_curve01,
PaintEffects->Curve Utilities->Attach
Brush to Curves, this will create
a new brush for the the stroke hair_split_curve01,
and some hair of course. Don't worry
if the hair looks like lightning strikes
:) Rename the new stroke to hair_side_stroke01(outliner),
and the new brush to hair_side_brush.
If you select the stroke in the outliner
and bring up attribute editor. Check
the brush tab, there's a load of sliders
here,
don't be put off by it, its categorized
well so you don't have to access many
settings that's not required here,
I'll go through all the ones that
requires to design our hair :)We'll
need to adjust the Global Scale according
to the size of the head, you can see
I have 0.150, but that is my character
is at 8cm tall. You should adjust
this so that the hair looks very short.
If your character is 160cm then leave
the Global scale at 3. This is your
over all pfx brush scale setting.
Open Brush Profiles and look at the
Brush Width, this will resemble the
how wide our hair emits grows from
the hair_split _curves, set it to
0.8,
just don't make it too low otherwise
your hair will look too flat. Leave
the rest of the slider default, oh
yeah ignore those other tabs on my
screenshots.
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