3ds Max 2012 Bible - Kelly L. Murdock [462]
To animate marbles falling into a glass bowl, follow these steps:
1. Open the Glass bowl of marbles.max file from the Chap 43 directory on the CD.
This file includes a glass bowl and several marbles positioned above its opening.
2. Right-click the main toolbar, and select MassFX Toolbar. Then select all the marbles located above the bowl, and click the Set Selected as Dynamic Rigid Body button.
3. Select the tabletop object, and click the Set Selected as Static Rigid Body button. This button is a flyout under the Set Selected as Dynamic Rigid Body button. Then click the Start Simulation button in the MassFX toolbar, and notice how the marbles all fall and spread out on the tabletop.
4. Select the bowl object, and set it as a static object by repeating Step 3. This time, the marbles all fall into the bowl.
Figure 43.3 shows the bowl full of marbles positioned using MassFX.
FIGURE 43.3
MassFX can compute all the collisions between all these marbles.
Setting Object Properties
One of the first steps in creating with a simulation is defining the object properties. For example, a simple sphere object in Max could represent a bowling ball, an orange, or a tennis ball. Each of these objects responds very differently when being animated to drop on the floor.
Setting the object type
All objects involved in a MassFX simulation must be assigned one of three object types. The available object types are:
• Dynamic: These objects move when they collide with other objects. Dynamic objects also are affected by gravity.
• Kinematic: These objects impact other dynamic objects in the scene, but they don't move when they collide with dynamic objects. They can be animated and often provide the force to the simulation. Kinematic objects are not affected by gravity.
• Static: These objects have an infinite mass and don't move when they collide with other objects. They frequently are used for ground and walls. They also are not affected by gravity.
These object types are available as buttons in the MassFX toolbar. To specify an object as one of these types, simply select the object and click the object type button in the toolbar. Any object with a defined object type is automatically added to the simulation. Any scene object without an object type is simply ignored.
Kinematic objects can be animated using standard keyframe animation and then be changed to a dynamic object at a given frame using the Until Frame value located in the Rigid Body Properties rollout. This provides a way to add forces to the simulation such as a marble that is animated being shot at a group of marbles. Just before colliding, you can set the shot marble to become dynamic so it continues its motion and then interacts with the other marbles based on the physics.
When one of the object types is assigned to an object, it appears as a modifier in the Modifier Stack. If you remove this modifier, the object is removed from the simulation and returned to its original state.
When an object's type is defined as a dynamic, kinematic, or static, the system automatically assigns some rough physical properties based on the object's size in the scene. Static objects, for example, are given a large mass, which essentially makes them immovable, and small dynamic objects are given very small mass values.
The Rigid Body Properties rollout also includes options for disabling gravity and collisions and computing for high-velocity objects.
When dynamic objects are placed in the scene, it is often difficult to get them positioned exactly on top of one another. Actually, it is better to have a small gap between objects so they don't overlap. Overlapping objects will repel one another when the simulation first starts causing motion before you want it. Within the Rigid Body Properties rollout is the Start in Sleep Mode option that causes all dynamic objects to freeze in their initial positions until hit by another object. Enabling this option helps prevent the initial movement of stacked objects when the simulation