Graphics Programs Reference
In-Depth Information
so that the empty local z -axis points in the same direction as the global y -axis. Increase
the “Strength” value to 10 and play the animation to see the sphere's particles being blown
(Figure 13.49). Wind strength is able to be animated, which creates a realistic wind effect.
13.9 Sample Particle Settings
The following are some sample settings for various uses. Follow the settings carefully other-
wise you will not get the results as demonstrated. Settings can be tweaked to produce what-
ever results you want and only by experimentation will you discover what can be achieved.
Remember to record settings for future use when you discover something especially neat.
13.9.1 Snow Effect
In a new scene, delete the cube and add a plane. Scale the plane up five times and subdivide
the surface four times. Position the plane at the top of the screen above the camera out of
camera view—the plane is there to emit particles, not to be included in the rendered image
or movie. Go to the properties window - “Scene” button and set “Gravity Z: -0.210.” This
is a low value since we want our snow to float down gently. Remember, if there are other
objects in the scene that are affected by gravity, they will also float.
Add a particle system to the plane. In the “Emission” tab, set “Lifetime: 200” and in the
“Velocity” tab set “Normal: 0.010” and “Random: 0.320.” We want the particles to display
for a fair amount of time, not go careering of at a hundred miles an hour. In the “Material”
button, add a material (white is appropriate) and set it as “Halo.” Set the halo size to 0.050
to make small snowflakes. Run the animation to generate particles then advance the anima-
tion to about frame 230 and render an image (Figure 13.50).
Animation as seen at frame 230
Figure 13.50
Place the plane above the
camera so it's out of view.
Rendered image
Snowflakes
 
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