Reactor (software)

Reactor is a physics engine developed by the Irish software company Havok for use in Autodesk 3ds Max. Reactor was fully integrated with 3ds Max from versions 5 to 2011. In 3ds Max 2012, Reactor was replaced by a PhysX-based engine called MassFX.^[1] Reactor was often used for realistic physics simulation that would be difficult or time-consuming to animate by hand.

When 3ds Max 5 came out in 2002, Reactor turned into an essential tool for animators and 3D artists. It was one part of a bigger package of updates that boosted modeling, animation, and simulation features. The engine made it possible to create more complex and realistic physics effects without having to animate everything frame by frame. This sped up and simplified jobs like simulating cloth, soft objects, and dynamic collisions for users.^[2]

By the time 3ds Max 9 came out, the Reactor module had been upgraded to a new version. It worked with newer versions of the Havok physics engine, like Havok 1.5 and Havok 3.2. These changes improved the calculation efficiency, especially for rigid body simulations. That allowed larger and more complex scenes to be calculated in less processing time. Reviewers at that time pointed out how the improved Havok integration let you see smoother real-time previews right in the 3ds Max viewport. This made it quicker to test and tweak physical interactions, like collisions or dynamic constraints, over and over. The updates also made simulations more stable when you had tons of objects in play. Plus, it handled interactions between lots of moving elements more accurately. All this opened up new ways to use Reactor for things like animation, visual effects, and prepping assets for games. This release was a major step. It helped Reactor develop better hardware and meet the increasing needs of professional 3D content creation.^[3]

Reactor is capable of computing rigid body, soft body, cloth, and rope collisions. Reactor can also simulate dynamics of any supported type interacting with a water volume, with adjustable viscosity and depth.

Reactor includes a large number of forces that can be used in simulation, apart from the default gravity: springs, dashpots, motors, wind, fractures (breakable objects), and a "toy car" type, with definable body/axis/wheels. Reactor also has many constraints available, including hinges, point-to-point constraints, prismatic constraints, car-wheel constraints, point-to-path constraints, and ragdoll constraints to simulate a lifeless body. In addition, Reactor is compatible with Space Warp modifiers in 3ds Max.