3ds Max 2012 Bible - Kelly L. Murdock [469]
4. Set the Simulation to run from 0 to 10 frames, and then open and specify a stat file location. The path of the stat file location is displayed. Then click the Run button to start the simulation. The precomputed values are saved to stat files.
5. Select the Precomputed mode option and drag through the animation frames to see how the hair reacts.
Figure 44.2 shows the hair bending to one side as the female head moves.
FIGURE 44.2
Using precomputed hair can save you a bundle of time when rendering.
Simulating Cloth Dynamics
Hair isn't the only system that has the benefit of dynamic motion. Cloth also can benefit from dynamic simulations. The steps for setting up a dynamic cloth simulation are similar to those for hair. First, apply the cloth modifier and define the cloth properties and the environmental forces acting on the cloth. Then run the simulation.
Defining cloth properties and forces
To add objects (both cloth and collision objects) to the simulation, click the Object Properties button in the Object rollout. This opens the Object Properties dialog box, shown in Figure 44.3. Clicking the Add Objects button lets you select scene objects to add to the simulation. Only objects added to the scene are included in the simulation. If an object isn't added, it's ignored. All objects added to the simulation are added to the list at the left. Selected objects in the list can be specified as Inactive, Cloth, or Collision Object. For Cloth and Collision Objects, you can set properties. You also can load and save cloth presets. Cloth presets are saved using the .sti extension.
Tip
If the cloth tends to pass through objects, then you can increase the Offset value for the collision object. •
FIGURE 44.3
The Object Properties dialog box lets you define the properties of cloth and collision objects.
After all the objects involved in the simulation are included and defined, you can set the simulation range in the Simulation Parameters rollout. The initial state for the object to be draped may be set using the Set Initial State button, which is located in the Object rollout. The Cloth Forces button, in the Object rollout, opens a simple dialog box where you can select to add additional forces to the simulation. Gravity is added by default, but you can change its value in the Simulation Parameters rollout.
Creating a cloth simulation
After completing the initial setup, clicking the Simulate button starts the simulation process. The objects are updated in the viewport as each frame is calculated. After every frame is calculated, you can see the entire dynamic simulation by dragging the Time Slider or clicking the Play Animation button. If you want to drape the cloth without running it over several frames, you can use the Simulate Local button. The Simulate Local (damped) button causes the simulation to run local with a large amount of damping, which is useful if the cloth tends to drape too fast. If you want to remove the current simulation because some properties have changed, click the Erase Simulation button, or you can remove all frames after the current simulation frame with the Truncate Simulation button.
Tip
If the simulation is taking too long to compute, you can cancel the simulation by pressing the Escape button. •
If you need to change a cloth or force property, click Erase Simulation, make the change, and run the simulation again. Simulation motions can be saved as keys with the Create Keys button. Figure 44.4 shows a simple plane object that has been draped over a chair over the course of 100 frames.
FIGURE 44.4
After you've defined cloth and force properties, an executed simulation drapes the cloth over a chair.
Viewing cloth tension
For cloth objects created using the Garment Maker modifier, you can view the tension in the cloth using the Tension option in the Simulation Parameters rollout. This option shows the areas of greatest