Page 1109 - Kitab3DsMax

Chapter 43: Simulating Physics-Based Motion with reactor
Note
After you’ve clicked the Create Animation menu command, a warning appears stating that the operation cannot
be undone. n
Analyzing the scene
After the Preview window is opened, a warning dialog box appears if the scene has any errors or warnings
that could cause trouble with the simulation. It also warns of unrealistic data, such as property settings that
are too high or too low.
Tip
The one warning that isn’t included in the warning dialog box is if objects have no Mass value. If objects in your
simulation are just sitting there, then make sure that they have a Mass value. n
If you want to check your scene without opening the Preview window, you can use the Animation ➪ reac-
tor ➪ Utilities ➪ Analyze World menu command. This command checks your scene for any trouble and
presents problems in a dialog box. If no problems are found, then a separate dialog box tells you that no
problems were found.
Tutorial: Dropping a plate of donuts
All the great books have an element of tragedy, so consider a policeman carrying a dozen donuts on a plate
when he stumbles and drops the plate. Donuts everywhere, how tragic! This animation sequence would be
difficult or at least time-consuming if it were not for reactor.
To use reactor to animate a falling plate of donuts, follow these steps:
1. Open the Falling plate of donuts.max file from the Chap 43 directory on the DVD.
This file includes a simple plate of donuts created from primitives.
2. Select the Animation ➪ reactor ➪ Create Objects ➪ Rigid Body Collection menu command, and
click in the Front viewport. In the RB Collection Properties rollout, click the Pick button and
select the plate object. Click the Pick button again, and select the Box object that represents
the floor.
3. Select the Torus objects, and choose Animation ➪ reactor ➪ Apply Modifier ➪ Soft Body Modifier
(or click the Soft Body Modifier button in the reactor toolbar).
4. Then select Animation ➪ reactor ➪ Create Objects ➪ Soft Body Collection, and click again in the
Front viewport. In the SB Collection Properties rollout, click the Add button and select all the
Torus objects again.
5. Select Animation ➪ reactor ➪ Open Property Editor, and select the Box object; in the Properties
rollout, enable the Unyielding option. Select the plate object, and make its Mass value 5.0. Then
select all the donuts, and make their Mass value 0.25. Enable the Mesh Convex Hull option.
6. The last step is to execute the simulation: Select the Animation ➪ reactor ➪ Create Animation
menu command. It takes some time to compute a solution for this example. When it completes,
press the Play Animation button (or press the / key) to see the results.
Figure 43.10 shows the upturned plate of donuts.

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