Hello
and welcome to the third installment of my procedural tutorials. This will be
a quite advanced tutorial since the final result will include a ton of layered
procedurals, a vertex colour mask, some bitmap masks and a gradient ramp with
LOTS of flags. This is what my version looks like, hopefully the end result of
this tutorial will be somewhat similar (click the image for a larger version)
If
you don't have a clue what I'm talking about when I say procedural, I suggest
reading the help file that comes with 3dsmax. Or you can look through part one
of this series, Procedural Wood and then proceed to tutorial number two, Anisotropic
metal shader.
I
will asume that you know what you're doing in the material editor in 3dsmax and
that you don't need a number specific tutorials. Due to the complexity of this
material, I won't be putting up images for every little dialog that pops up. I
will however do my best to make it easy to follow my logic (what logic?).
One
VERY important thing to remember when dealing with procedural maps is that size
matters. The scale of your scene and the scale of my scene will most likely not
be the same. Thus, a size of 10 for a noise map might look right in my scene,
but be way too small or too big in your scene. I will put some scene specifics
at the beginning of the tutorial. Another thing to remember is that the scale
of the sphere in the material editor will of course affect the look of the material
in the material preview. Which is another thing I will touch on.
Lastly,
this material can be summed up in one sentence: you use vertex colours to specify
where you want the mud, then you use two bitmaps and some cellular trickery to
mask in the water between the cracks. That's the extremely short version of it.
Now on to the long version.
Maps used
First
of all, lets review what we'll be using for this shader.
•
Noise
map. We will be putting this one to good use. I recommend downloading
the Blur Noise map (avaliable from the Blur
Beta page) because you can have level settings higher than 10. This is very
good when you have a large size but you still want the fine detail. Regular noise
works well too of course since pretty much everything but the number of avaliable
levels is the same. One thing to take note of: the regular noise can be displayed
in the viewport, blur noise can't.
•
Cellular
map. This one is another very versatile map which will be used for the
cracked mud.
•
Mix
map. This map is impossible to do without. The ability to mix maps is
essential to a good material.
•
Composite
map. It does what it says. Composites different maps together, pretty
much the same way layers work in Photoshop, but without the lovely opacity controls
and blending modes. On a side note, there is a plugin in development that features
just that, Photoshop style blending of maps. It can be picked up from Michael
Spaw, the Max Plugin section.
•
Falloff
map. The falloff map is another map that is incredibly useful. You can
use it to fade between two colours or maps depending on light/shadow, perpendicularity
to the camera etc etc. Read all about it in the documentation.
•
Output
map. Another neat little map. This one will let you adjust the colour
values, output ammount, offset and a bunch of other stuff. One of the most interesting
uses, in this tutorial, is the Bump Ammount spinner. We will use it to tweak the
different layers of the bump maps used. It has two siblings by the name of RGB
Multiply and RGB Tint. They are geared towards colour correcting only though.
Lastly, I must mention Color Correct by
Cuneyt Ozdas which is like the output map on steroids. Visit that site for
more must-have plugins.
•
Raytrace
map. This is just to add reflections to the water. It's pretty darn slow
when you mask it as we will be doing though, so you might want to find another
solution (environment mapping for example) or render in passes.
•
Electric
map. The Electric map blended with the Noise map gives a very nice bump
map as I will be showing later. It's also handy for caustic effects in pools and
on sea floors for example. Avaliable from the Blur
Beta page.
•
Solid
Color map. This is just what the name says. A solid colour map. If, for
example you need a completely white material, this can give you that. And you
have controlable alpha value too. Very simple, and pretty usefull now and then.
Avaliable from the Blur Beta page.
What do we want?
When
I started making the canyon material, I had in mind something with sediment layers,
a rocky surface and a stream at the bottom. On either side of the stream there
would be a band of cracked mud, with water snaking trough the cracks. Since I
didn't plan on modeling the cracked mud, the snaking water would have to be part
of the material and not a separate plane with a water material applied. A separate
plane would've produced a very cg look because of the smooth intersection of water
and canyon wall. I set off to find reference, and for some reason I can't find
as nice refrences this time around. I found some really nice shots from Myst 3
- Exile and some other general images. I did a quick search for this tutorial
and came up with this photo, an
image from Myst 3 - Exile and another image from
Exile. They aren't the best, but as I had a pretty clear idea when I started,
I didn't really need much reference. Besides, I had an irc channel I could bug
with updates. Co-workers, friends and irc are great ways to get feedback fast.
Very much recommended.
Onwards!
General info
First
of all, in my canyon scene, you can fit a sphere with a 65 unit radius between
the canyon walls. The material editor 3d Map Sample Scale is set to 25 (it's in
the options dialog). This will affect how large the procedural maps will appear
in the material preview, and it will be one reason that your maps might not look
the same as the screenshots. I also cheated somewhat with the uv-mapping of the
walls and the vertex painting. I applied a uvw modifier, collapsed the stack and
then edited the geometry to get the sediments to be even more wavy than they actually
are. You don't have to do this, but it helps. For the vertex painting, the higher
resolution mesh, the smoother the vertex colouring. I started to paint the general
outline of the stream, then I applied a meshsmooth (1 iteration) and painted on
top of that to get more detail. You could keep doing this, but the end result
will be a fairly heavy mesh, and it's not always worth it.
The colour map
Lets
start with the colour map (aka diffuse map). It will need one layer with sediment,
a gradient ramp with a bunch of colours jammed together. Then there is the mud
layer, and some general splotches of colour to top it all off. The water will
be the last, and trickiest, layer. Here's a screenshot of the completed
diffuse tree including the water. Please note the naming of materials. VERY
IMPORTANT. When I did this material I didn't name a single map, and it's taken
me quite a while to sort it all out :) Below is a render of the diffuse map with
a vertex colour mask. Looks boring without the bump map...
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How the f...?
•
Start
by putting a Composite material, with two map slots, in the diffuse slot. The
first one will be the canyon wall and mud diffuse, the second will be used for
water. I will say this one last time, name the maps so you can easily navigate
the material tree later on. Right, the Composite map will be called "Diffuse
- Main Composite".
•
Put
a Mix map in slot one, this will be used to mix the mud and canyon wall diffuse
maps with a Vertex Colour map. Put a Cellular
map in the first mix slot and adjust the values accordingly, then put Noise
maps in the colour slot and the
first division slot. This is to give the mud more variation.
•
On
to the canyon wall. The canyon wall map is a mix between a Gradient Ramp and an
Electric map. Put a Mix map in the slot below the mud to begin with. Name it "canyon
wall diffuse mix" (or "blah" :) In the first slot you put the
Gradient Ramp, name it "sediment lines".
Here
comes one of the tedious parts: creating the sediment lines by adding a bunch
of flags and giving them slightly different colour. Just click in the gradient
some 10-20 times, then right click a flag, chose properties. Then you can just
use the arrows in that window to jump from flag to flag, adjust the position,
and the colour without having to select each flag individually. This is also where
canyon reference comes in handy, so you can get a general idea of how the sediment
lines look. Displaying the map in the viewport is a good way to get feedback on
how thick the bands are and how much the noise is affecting it. The reason I have
a 1.7 tile on the gradient ramp is that I uv mapped the canyon very sloppily,
and that it's easier to edit the gradient ramp when it's tiled. You don't have
to have as many flags to get thin stripes.
•
In
the second slot we dump an Electric map, the "general
splotch" map. This is just to get some general colour splotches on top
of the sediment layer. The mix value I used is around 35. Not too strong, or the
colour of the sediments will be all but lost.
•
Back
up one level to the "canyon wall diffuse mix". This is a neat little
trick: put a Vertex Colour Map in the mix amount slot. This will let you use the
nice little vertex colour map you painted (or will paint) as a mask. That's how
I did the smiley face on the sphere, just slap a Vertex Paint modifier on the
sphere, start drawing and you're set. Very handy in other cases too, for example
painting dirt, shadows etc. Be creative! Here's a screenshot of the canyon
and mud mix map.
I'm
going to discuss the water map last of all, because it will use a lot of map instancing
from the bump map for use as masks and some bitmap trickery. Which means, we move
on to the bump map.
