Graphics Reference
In-Depth Information
The table is a fairly complex object, and it shouldn't be a surprise that it could slow down particle calcula-
tions to use something like this as a collision object. The system has to calculate the possible intersection
of every particle with every face of the table. To speed things up, you could add a simple filled circle to
the scene and position it to correspond with the tabletop. Enable collision for the filled circle, use the
Particle Cache
panel to bake the particle simulation, then move the circle to a nonrendering layer.
Once your particle system moves as you like in the 3D view, you need to assign materials properly for
rendering.
The Halo Material
The
Halo
material type was developed specifically for use with particle systems.
Figure 13.14
shows the
Material properties, set to Halo in the topmost panel. Also in the figure is a render of a cluster of points
with the default Halo properties.
Shading panel properties are reduced to an Alpha slider. On the Halo panel, the following options are
available:
●
Color:
The color of the halo
●
Size:
The apparent size of the halo. It isn't measured in Blender units, so you'll just have to execute
a trial-and-error process to find an appropriate value.
●
Hardness:
This controls the concentration of the “core” of the halo. The maximum value, 127,
creates a hard center with fuzz around it. The lowest, 0, spreads the core over the whole area of the
halo, creating a blob of fairly uniform density.
●
Add:
Halos are self-illuminated. They will render even in a scene with no lamps. With
Add
at 0.0,
the default, this self-illumination is the same no matter how many halos are in an area. When raised
up to 1.0 though, the illumination of stacked halos is reinforcing.
Figure 13.15
shows the difference.
In general, particles that are supposed to create their own light (fire, magic, etc.) should use the Add
property.
●
Rings/Lines/Stars:
These toggles add effects to the halo, letting you create sparkly magic for your
unicorn and pony animations. Each has a different visualization, shown in
Figure 13.15
. They are
independent, so you can enable them in any combination. The color swatches below Rings and Lines
control the effect's colorization.
●
Soft:
Halos aren't rendered as real geometry. They are a postprocessing effect that is blended into the
scene using the render's Z (depth) values. This can lead to halos ending abruptly when they intersect
rendered meshes. To eliminate this effect, enable
Soft
. Personally, I always enable it.
●
Shaded:
The last option of note. Halos, as we mentioned, are self-illuminating unless you enable
Shaded
. This option causes halos to receive their shadow and lighting from the surrounding scene.
Useful in the past for effects like smoke, it has mostly been supplanted by the smoke simulator and
volume rendering.
The real trick with setting up halo materials lies in achieving the right balance between Alpha, halo size,
and the total number of particles. All three of those values influence the visual density of the rendered
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