Page 1043 - Kitab3DsMax

Chapter 41: Creating Particles and Particle Flow
the advanced systems—Particle Flow Source, Super Spray, and Blizzard—include multiple Parameters roll-
outs. The PArray and PCloud systems have similar multiple rollouts, with a few subtle differences, and the
Particle Flow system includes several rollouts, but most of the action is with the Particle Flow window. The
following sections describe how to use these rollouts to set the parameters for the various particle systems.
Using the Spray and Snow Particle Systems
All I can say about the Spray and Snow particle systems is that when it rains, it pours. The Spray Parameters
rollout includes values for the number of particles to be included in the system. These values can be differ-
ent for the viewport and the renderer. By limiting the number of particles displayed in the viewport, you
can make the viewport updates quicker. You also can specify the drop size, initial speed, and variation. The
Variation value alters the spread of the particles’ initial speed and direction. A Variation value of 0 makes
the particles travel in a straight line away from the emitter.
Spray particles can be Drops, Dots, or Ticks, which affect how the particles look only in the viewport. Drops
appear as streaks, Dots are simple points, and Ticks are small plus signs. You also can set how the particles are
rendered—as Tetrahedron objects or as Facing objects (square faces that always face the viewer).
Note
The Facing option is visible only in the Perspective view but can be rendered using any viewport, including a
camera viewport. n
The Timing values determine when the particles appear and how long the particles stay around. The Start
Frame is the first frame where particles begin to appear, and the Life value determines the number of frames
in which the particles are visible. When a particle’s lifetime is up, it disappears. The Birth Rate value lets
you set how many new particles appear in each frame; you can use this setting or select the Constant
option. The Constant option determines the Birth Rate value by dividing the total number of particles by
the number of frames.
The emitter dimensions specify the width and height of the emitter gizmo. You also can hide the emitter
with the Hide option.
Note
The Hide option hides the emitter only in the viewports. Emitters are never rendered. n

The parameters for the Snow particle system are similar to the Spray particle system, except for a few
unique settings. Snow can be set with a Tumble and Tumble Rate. The Tumble value can range from 0 to 1,
with 1 causing a maximum amount of rotation. The Tumble Rate determines the speed of the rotation.

The Render options are also different for the Snow particle system. The three options are Six Point,
Triangle, and Facing. The Six Point option renders the particle as a six-pointed star. Triangles and Facing
objects are single faces.

Tutorial: Creating rain showers
One of the simplest uses for particle systems is to simulate rain or snow. In this tutorial, you use the Spray
system to create rain and then learn how to use the Snow system to create snow.
To create a scene with rain using the Spray particle system, follow these steps:
1. Open the Simple rain.max file from the Chap 41 directory on the DVD.

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