Now
that we've completed the bump and diffuse maps, it's time to create the water
portion of the diffuse map. Some of you might wonder why I'm putting the water
in the same material as the rest instead of using a plane or something similar.
The reason for this is that the canyon mesh in itself is smooth. If you wanted
to have water between the cracks of the mud, yuo'd have to model the cracks by
using a displacement map (or by hand if you feel like going insane) This one uses
2 bitmaps to mask the water, and it will be very scene specific. First of all,
lets look at what we need for the water to work. Click the images for larger versions.
•
We
will need one bitmap for where the water flows. The main stream, small ringlets
of water joining or branching off from the main stream etc. On my model, that
looks like the picture on the right:
We
will also need a mask for the area where water has spread in between the cracks
in the mud material. It will basically be the same map as the water mask, but
a blurred and expanded version. On the left is the actual mudmask, on the right
it has been layered on top of the water mask:
The
small white area that we get with these two maps is where the water between the
cracks will appear.
•
If
we add the vertex colour map to the equation, you will see how it all fits together.
On the left, just the vertex colour map, on the right, all three elements together:
Here
you can see how you have the mud as a wide dark grey area, then you have the little
white band where the water has gathered in the cracks, and in the middle the actual
water.
These
are the only maps you need to make the water composite work. The order in which
you create the maps is entirely up to you, although I can offer some tips. Start
out by drawing a small stream with vertex colours on your model. It doesn't have
to be very detailed, just a gnereal purpose stream. Export this using Texporter
and bring it into Photoshop or other paint program to paint a detailed water mask.
That way, you get a rough sketch you can paint on top of. When you're done with
the water mask, show the texture in the viewport and paint the mud layer on top
of it with vertex colours. Since you can display both textures and vertex colours
in the viewport, it makes painting the mud a breeze. No guessing where the water
will be etc.
Next
we will put these maps to use. I've tried to name the materials so it's easy to
follow what each will do. Let's rock.
As
you can see, it looks fairly straightforward. But! Appearances can be decieving.
It's a neat little bit of mask trickery if I may say so myself. Lets begin.
•
In
the diffuse main composite map, put a new Mask map in slot two. Name this "water".
In the map slot, put another Mask map. Call it "water
diffuse mask". Please note that I've checked the "Invert Mask"
check box. If you don't want to do that, you will have to invert the colours of
most of the maps used in the water mask. I just checked that box instead.
•
In
the map slot, you will have a Noise map that will give the water it's colour.
I slapped a Noise map named "water diffuse"
in that slot and you will too. The colour settings is entirely up to you, maybe
you want a river of molten lava instead of plain boring water? Or maybe radioactive
waste? It's all possible! In the mask slot we will put a Composite map, aptly
named "water and mud masks", because
that's what we're putting there.
•
This
Composite map will have three slots. The first one will be "white base",
a completely white map thanks to the Solid Color map. It will be our tabula rasa
on which we will add our other maps. The second slot starts out with a Mask map,
"cracked mud mask". In the map
slot, put a Mix map, the "cracked
mud adjustment layer". The name describes the function perfectly. By
adjusting the mix value, you can adjust how opaque the water in the cracks will
be. Speaking of cracks, instance the "same settings as colour mud" Cellular
map from the bump tree into the first mix slot. I have the mix value at about
70, if you lower it, the water between the cracks will be more visible, and if
you raise it, the cracks will dissapear.
•
Go
back up one level to the "cracked mud mask"
and put the "extended mud mask bitmap"
in the mask slot. As you see, this one controls the cracks on top of the white
background. The one thing missing now is the water itself, which will appear in
slot number three.
•
Slot
number three is the last slot of our Composite map named "water and mud maks".
This one will host the water itself and it's pretty simple. Add a Mask map, named
"water transparency mask". In the map slot, a Noise map will reside,
named "water transparency map".
The mask will be the "water map" I talked
about earlier. The only thing to keep in mind here is that the colour of the noise
map, and the transparency of the cracks must be somewhat similar. You could elaborate
on the "water transparency map" setup, such as adding another Mix map
to control the overall transparency. This would make it easier to match it to
the transparency of the cracks. On the other hand, you can just wing it, which
I did. Or, if you don't want to simulate the slightly different transparency of
water with a noise map, you could just put a Solid Color map in there instead
of the Noise map. One last thing left for the water.
•
Go
back up to the first Mask map called "water". In the mask slot, put
a Falloff map, name it "fresnel transparency
fake". Using this, we can simulate the fresnel effect. Note that you
can adjust the IOR in the Falloff map or in the extended parameters of the material.
I set my IOR to 1.4, and tweaked the mix curve to make the water a little less
opaque.
Here
are a couple of sample images. Without the Falloff map:
With
the Falloff map:
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With
the Falloff map enabled, the bump maps and the mud diffuse:
For
some reason I really like that last version. I wonder why. Well, that concludes
the diffuse version of the water map. Now we can create the water part of the
bump map, the specular map and the reflection map. These will mostly be pretty
straight forward copying of the original water map we just created.
