reactor is a toolset that allows animators and artists to control and simulate complex physical scenes in 3ds Max. reactor supports integrated rigid and soft body dynamics, cloth simulation, and fluid simulation. It can simulate constraints and joints for articulated bodies. It can also simulate physical behaviors such as wind and motors. You can use all of these features to create rich dynamic environments.

In a reactor simulation, a rag-doll figure crashes through a window.

Once you have created an object in 3ds Max, you can assign physical properties such as mass, friction, and elasticity to it with reactor. Objects can be fixed, free, attached to springs, or attached together using a variety of constraints. By assigning physical characteristics to objects like this, you can model real-world scenarios and then simulate them to produce physically accurate, keyframed animations.

After you set up your reactor scene, you can preview it quickly using the real-time simulation display window. This allows you to test and play with a scene interactively. You can alter positions of all physical objects in the scene, dramatically reducing the design time. You can then transfer the scene back into 3ds Max with a single mouse click while retaining all the properties needed for the animation.

reactor frees you from having to hand-animate time-consuming secondary effects, like exploding buildings or draping curtains. reactor also supports all standard 3ds Max functionality such as keyframes and skinning, so you can use both conventional and physical animation in the same scene. Convenient utilities, such as automatic keyframe reduction, let you tweak and alter the physically generated parts of an animation after it has been created.

The remainder of this chapter describes each of reactor's features in detail. Also, the included tutorials step you through creating some typical reactor scenes. Together, we hope these will help you to get the most from reactor.

If you would like to find out more about dynamics simulation, see Introducing Dynamics Simulation.

Getting Started

This section shows you where to find the various reactor options in 3ds Max, as well as introducing you to reactor's helper icons. You'll see how to use each of the options in the relevant section of this guide.

Command Panel

You can use the reactor options on the Create panel to create various reactor elements. To find most reactor objects, go to the Helpers sub-panel, and then, from the drop-down list, choose reactor.

You can also find a space warp, used for water, in Space Warps reactor.

Once you've created a reactor object, selecting the object and opening the Modify panel allows you to configure its properties.

There are also three reactor modifiers, used to simulate deformable bodies:

You'll find most of the remaining reactor functions on the Utilities panel. This provides access to functionality such as previewing the simulation, changing world and display parameters, and analyzing the convexity of objects. It also lets you see and edit the rigid body properties associated with objects in the scene.

NoteThe reactor menus and toolbar provide shortcuts for many of the reactor functions provided in the command panel.

The reactor Toolbar

The reactor toolbar is a handy way to access much of reactor's functionality. It has buttons that let you quickly create constraints and other helpers, display physical properties, generate animations, and run the real-time preview.

To display the reactor toolbar:

  1. Right-click an empty area of the main toolbar to display a list of available toolbars.
  2. Click reactor.

The reactor Submenu

The main reactor submenu, available from the Animation menu, is another way to access reactor functionality.

The reactor Quad Menu

A further quick way to access reactor options is the reactor quad menu. To open this menu, press Shift+Alt and right-click in the active viewport.

Helper Icons

Many reactor elements, such as constraints and the Rigid Body Collection, have their own special helper icon that appears in the viewport when you add them to the scene. For instance, the following illustration shows the Hinge constraint icon:

Although the helper icon doesn't appear in your rendered scene, the icon's appearance (and in some cases, its position and orientation) will help you to set up your reactor scene correctly.

When selected, reactor icons are white and are also larger than when not selected. When not selected, the icon for a valid element is blue, and for an invalid element is red. What constitutes validity depends on the particular reactor element. For instance, a hinge is valid if it has the correct number of objects attached to it; a Rigid Body Collection is valid if it's not empty. Invalid elements are excluded from the simulation, and reported as errors.

Certain icons provide additional information about how the element behaves in the simulation. For example, the display for a valid hinge indicates the hinge position, and, when selected, the hinge axis and any limits youvl have specified for the movement of the hinged bodies.