If you were following Autodesk 3ds Max 2012 development process, you’ve already may know that built-in Havok Reactor physics simulation engine was replaced with a new MassFX unified simulation, using PhysX SDK integration.

However, since only mRigids solver (rigid body and joints dynamics) is available so far, one may say that Reactor was omitted too early, since not all the functionality (cloth, joint motors, forcefields, buoyancy) is present in MassFX currently.

Generally, MassFX is based on modified NVIDIA PhysX plug-in for 3ds Max (likely latest 2.60), and thus, resembles its basic functionality and interface, but several differences can be spotted:

Simulation in viewports runs much faster and smoother, thanks to new Nitrous graphics core. Performance Viewer tool, that can be found in PhysX plug-in 2.60, was removed.

tool, that can be found in PhysX plug-in 2.60, was removed. APEX Clothing functionality is not available.

functionality is not available. Dynamic ragdolls are not available.

are not available. Minor interface changes.

Note: MassFX does not support hardware acceleration currently.

Note #2: To avoid slowdowns while working with massive amount of objects, it is recommended to disable rendering of physical meshes (MassFX Toolbar > Display > Display Physical Meshes).

Previously, Autodesk has mentioned that future releases of MassFX will support cloth, softbody and ropes simulation, deformable meshes, fluids and forcefields.

Update: MassFX 2013 in review

Also, according to our knowledge, users will be able to install PhysX plug-ins from NVIDIA over MassFX, to enhance it with additional functionality.