Animation
Keyframes and interpolation
Animation in 3ds Max is driven by keys on tracks. The Dope Sheet and Curve Editor expose keys and tangents. Candidates must know interpolation types: linear, smooth (Bezier), step, and ease curves. A classic trap: changing a key's tangent affects the segments on both sides, while moving a key changes timing only. Auto Key creates keys when a parameter changes; Set Key requires explicit key creation.
Controllers and constraints
The default controller is usually Bezier (Position XYZ for transforms). Controllers include Position XYZ, Euler XYZ, TCB, and List. Constraints such as Path, LookAt, Link, and Orientation drive transforms from other objects. Note that constraints override manual keys unless weighted or blended.
Hierarchies and rigging basics
Parent/child links propagate transforms; pivots and linking affect behavior. Bones, the Skin and Morpher modifiers, and CAT/Biped rigs are common. Understand that Skin binds mesh vertices to bones via envelopes or weights, and that Morpher blends between target shapes.
Time configuration and playback
Frame rate, playback range, and real-time playback settings affect previews but not the stored animation. Track View and the Motion panel (trajectories) help diagnose motion.
Worked example
A ball bounces: key position at contact frames with fast-in/fast-out tangents, then add a stretch on the way down and squash at contact using a scale key. Use the Curve Editor to shape the vertical position as a parabola rather than relying on default smooth tangents.
Rule of thumb
Animate the extremes and let interpolation do the in-betweens; adjust tangents to control weight and timing.