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Chapter 41: Creating Particles and Particle Flow
particles after collisions as a percentage of their collision speed. You can vary the amount of Bounce with
the Variation value.
Tutorial: Basketball shooting practice
When an entire team is warming up before a basketball game, the space around the basketball hoop is quite
chaotic—with basketballs flying in all directions. In this tutorial, you use a basketball object as a particle
and spread it around a hoop. (Watch out for flying basketballs!)
To use a basketball object as a particle, follow these steps:
1. Open the Basketballs at a hoop.max file from the Chap 41 directory on the DVD.
This file includes basketball and basketball hoop models created by Zygote Media.
2. Select the Create ➪ Particles ➪ Super Spray menu command, and drag the icon in the viewport.
Position the icon in the Front view so that its origin is above and slightly in front of the hoop and
the directional vector is pointing down. (You need to rotate the emitter icon.)
3. Open the Modify panel, and in the Basic Parameters rollout, set the Off Axis Spread value to 90
and the Off Plane Spread value to 40; this randomly spreads the basketballs around the hoop. In
the Viewport Display group of the Basic Parameters rollout, select the Mesh option. Set the
Percentage of Particles to 100 percent to see the position of each basketball object in the viewport.
Caution
Because the basketball is a fairly complex model, using the Mesh option severely slows down the viewport update.
You can speed the viewport display using the Bbox (Bounding Box) option, but you’ll need to choose it after
selecting the Instanced Geometry option. n
4. In the Particle Generation rollout, select the Use Total option, and enter 30 for the value. (This
number is reasonable and not uncommon during warm-ups.) Set the Speed value to 0.2 and the
Life value to 100 because you don’t want basketballs to disappear. Because of the low number of
particles, you can disable the Subframe Sampling option. Set the Grow For and Fade For values to
0.
5. In the Particle Type rollout, select the Instanced Geometry option and click the Pick Object but-
ton. Make sure that the Use Subtree Also option is selected to get the entire group, and then select
the basketball group in the viewport. At the bottom of this rollout, select the Instanced Geometry
option and click the Get Material From button to give all the particles the same material as the
original object.
6. In the Rotation and Collision rollout, set the Spin Time to 100 to make the basketballs spin as
they move about the scene. Set the Spin Axis Control to Random. Also enable the Interparticle
Collisions option, and set the Calculation Interval to 1 and the Bounce value to 100.
With the Collisions option enabled, the basketballs are prevented from overlapping one another.
7. At the floor of the basketball hoop is a Deflector Space Warp. Click the Bind to Space Warp but-
ton on the main toolbar, and drag from this floor deflector to the Super Spray icon.
This makes the basketballs bounce off the floor.
Figure 41.11 shows a rendered image of the scene at frame 30 with several basketballs bouncing chaotically
around a hoop.

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