far the container is filled with solid white Density.
To create the cloud effect, you texture the Density so
that some areas are transparent and some areas are opaque.
To texture the density of a fluid
- Turn on hardware texturing display so
you can see the effect of the textures on the fluid without rendering
by selecting Shading > Hardware Texturing from
the scene view menu.
- Open the Textures section
in the Attribute Editor.
- Turn on Texture Opacity to
apply the current texture to Opacity values.
The current texture is Perlin Noise,
defined by Texture Type.
Notice that the Density now
has a slightly blotchy look to it, with areas that are more opaque
and areas that are more transparent. This texture provides the standard
3D noise used in the 3D Solid Fractal texture included
- Change Texture
Type to Billow for a fluffy, cloud-like
The Billow texture
is computationally intensive and therefore slower than the other
- Change the look of the texture by setting
the following texture attributes:
- Amplitude: 0.5
- Depth Max: 4
Decreasing the Amplitude makes
the areas with low Density more transparent and
the areas with high Density more opaque.
Max adds detail. Increasing it will also increase render
- Stretch the texture in the X direction by changing the
X, Y, and Z components of the Texture Scale to
2, 1, 1.
- Change the following Billow texture attributes
to make the “billows” less dense, more spotty, and with randomly
- Billow Density: 0.6
- Spottyness: 2.0
- Size Rand: 0.40
the Opacity so that areas in the
container that are very dense appear less opaque, areas that have
very little Density become totally transparent,
and the transition between areas that are totally transparent and
areas that are more opaque is less gradual.
In the Attribute
Editor, go to the Shading section.
Look at the Opacity graph in the Opacity subsection. This
graph represents the relationship between Opacity values
and Density values (the Opacity
range from 0 on the bottom (totally transparent, no opacity) to
1 on the top (totally opaque).
range from 0 on the left side (no Density)
to 1 on the right side (high Density).
So for the linear graph
shown above, where Density values are 0, Opacity values
are 0, making the Density totally transparent,
where Density values are 0.5, Opacity values
are 0.5, making the Density partially opaque, and
where Density values are 1, Opacity values
are 1, making the Density totally opaque.
- Click the first dot on the Opacity graph
to select the position marker. Position markers mark the location
on the graph from left to right (the Opacity Input value).
The outline of the dot is white when a position is selected.
- Change Selected Position to
0.10 to change the position of the marker.
The position marker moves
to the right. Now, for Density values
between 0 and 0.10, the Opacity values
will be 0. This means that Density that
was previously partially transparent will be completely transparent.
The more transparent
areas of cloud disappeared, but now the solid areas of cloud are
- Click on the graph to create a new position
- Change the marker position and value
- Selected Position: 0.15
- Selected Value:
that are greater than 0.15 are now more opaque, and the transition
between areas of total transparency (Opacity 0),
and areas where the Density becomes more visible
(Density 0.15) is less gradual.