257
Chapter 9
Light Fog, Fluids, and
Another Look at Materials
W
    take another look at materials. We will tile a texture to cover a large
area, experiment with a few dierent ways to make glass, render with the mental
ray renderer, and make a material look like a light source. Along the way, we will slip in a
light eect called fog and we will use a uid particle eect.
FIXING A TILED TEXTURE WITH OVERLAYS
A common task when creating 3D models is prepping a le texture that looks great on its
own but needs to be repeated in order to cover a large area. Most of the time you cannot
simply enlarge the texture. Even if you have a photo-enlarging application that will allow
you to add pixels so that the image does not become pixelated as you enlarge it, it is usually
true that there is some natural granularity of the texture that needs to be preserved when
applying it to your model. If you have a brick wall, you do not want a twenty-foot expanse
of it covered with a single giant brick; what you need to do is take the texture you have on
hand and tile it.
We are going to look at the key problem of concealing what are oen obvious borders
between the individual tiles. With a brick wall, one way to do this is to use interlocking
sections of brick texture. is makes the job of tiling it very easy. Later, we will look at the
tougher problem of tiling a texture that does not have this interlocking property. Once
a texture has been prepped to be tiled without the edges of the tiles showing, we call it a
“seamless” texture.
If you do need a photo-enlarging application, a good product for enlarging images with-
out having to stretch the pixels is the onOne Perfect suite. It works as a stand-alone applica-
tion and as a Photoshop/Aperture/Lightroom plug-in.
258 3D Animation for the Raw Beginner Using Maya
Experimenting with Textures
Right now, we will look at a simple way to make those
seams between tiles less obvious. e goal is to get the
tiled texture to a point where the seams will not be
easily visible from whatever perspective and distance,
and under whatever lighting we plan to render it.
Adding Noise to the Tiling Lines
Remember our cactus texture? e tiled version of it is
shown in Figure9.1. We can clearly see the horizontal
lines in it, because they cut against the grain of the tex-
ture. What we want to do is soen those lines. One way
to do this is to use another texture to add some noise
to that tiled grain. We will do some experimentation to
see just what sort of texture, if added as a layer to our
tiled cactus texture, will get the job done.
Consider Figures9.2 and 9.3, these are the rust tex-
tures we looked at earlier. Now look at Figures9.4 and
9.5, these are organic textures, both of bushes. All four
of these textures oer a more irregular grain.
First, though, we need to decide just how to add this
layer to the tiled cactus texture. What we will use is a
“saturation” layer. Saturation refers to the brightness of
colors. Another way to look at it is that low saturation
tends to wash out a color. High saturation means the
color is more vibrant. Our goal will be to use the colors
of the new texture layer to inuence the colors of the
FIGURE 9.1 Original cactus patches.
FIGURE 9.2 Rusty metal 1. FIGURE 9.3 Rusty metal 2.

Get 3D Animation for the Raw Beginner Using Maya now with the O’Reilly learning platform.

O’Reilly members experience live online training, plus books, videos, and digital content from nearly 200 publishers.