Biped FAQs and Procedures

This topic contains procedures that answer frequently asked questions about Biped animation.

See also

To start a freeform animation

  1. Create a biped.

  2. Open the Motion panel to display Biped controls.

  3. Turn on the Animate button and move any part of the biped.

  4. Click Yes in the Freeform dialog.

  5. Turn on the Animate button and keyframe the biped limbs at various frames.

  6. Keyframe the biped center of mass position to move the entire biped.

    Keyframe the biped limbs and the center of mass at different frames to create your character animation. Click play to view results. The next How To explains how sliding feet can be rectified in a freeform animation.

To prevent sliding feet in a freeform animation

  1. Move the time slider to frame 0.

  2. Select a biped foot.

  3. Turn on the Animate button.

  4. On the Key Info rollout, set IK Blend to 1 and turn on Object (Body is selected by default).

    This puts the biped leg into world space. The foot stays planted if you move the center of mass to reposition the biped. New keys retain IK Blend and Object settings. IK Blend can be varied to 0 for foot keys in the air; this changes the foot trajectory from one footstep to the next. Tension, Continuity and Bias parameters also change trajectories.

  5. Repeat the process for the opposite foot.

    This makes it easier to re-position the biped without the feet sliding.

    Note: You can also use Set Planted Key in the IK Key Info rollout. This automatically sets IK Blend to 1 in Object space with Join to Prev IK Key turned on.

To reposition a biped with freeform animation

Unlike moving all the footsteps to reposition a character using footsteps, the center of mass is linked to a dummy and the dummy is moved to reposition a freeform animation.

  1. On the Create panel, click Helpers, then select Dummy.

  2. Create a dummy in the viewports.

    The dummy can be created anywhere.

  3. Select the biped center of mass.

  4. Click to turn on the Link tool on the 3DS MAX toolbar and drag from the center of mass object to the dummy object in the viewports.

  5. Select and move the dummy object to reposition the biped and its freeform motion.

    Note: The position spinners on the Motion Flow Script rollout can also be used to reposition a biped with freeform motion. After using the spinners to reposition the biped, use Save Segment to store a repositioned BIP file. Exit Motion Flow mode and load this BIP file (the one with the biped in a new position).

To make the biped stand still after a walk period (footstep animation)

This assumes you are working with a default walk, generated with Create Multiple Footsteps.

  1. Open Track View and stretch the tail edge of the last two footsteps to line up at the same frame in time to create a "stand still" period.

  2. In Footstep Mode, move the last footstep in space and position it next to the second-to-last footstep. The character's feet will be close together during the standing period.

    Note: The Bip01 transform track in Track View. The center of mass has a vertical, horizontal, and turning key at the end of the last footstep. The last frame of the footsteps should be lined up in time at this frame.

  3. Select Body Vertical in the Track Selection rollout, then use Next Key in the Key Info rollout to set the current frame at end of the last footstep.

  4. Click Copy Pose in the Keyframing rollout.

    This is a two-button flyout: be sure to click Copy Pose, not Copy Posture. The entire biped pose is stored.

  5. Use Previous Key in the Key Info rollout to find the vertical key at the start of the standing period and set the current frame.

  6. Click Paste Posture in the Keyframing rollout.

    The entire biped posture is pasted at this frame. Keys are inserted for the horizontal and turning tracks.

  7. In Track View, and for any biped track, delete keys that exist during the standing period.

  8. In the Key Info rollout you can decrease continuity for the vertical, horizontal and turning keys on either side of the standing period to eliminate motion between the keys.

To copy keys between bipeds

  1. Scrub the time slider to find a posture you want to copy.

  2. Select biped limbs and click Copy Posture on the Keyframing rollout.

  3. Select another biped in the scene.

  4. Click Paste Posture.

    Posture from the first biped is pasted to the second biped. One biped can remain in the scene as the posture biped; if you constantly need to use certain postures, key them at different frames on one biped, then copy and paste them to the biped you are animating. Use Copy Pose to copy the entire biped including the center of mass Position. Use Copy Posture to copy selected limbs.

To make the biped walk on a moving object in your scene

  1. Select the biped center of mass.

  2. Turn on the 3DS MAX link tool on the toolbar and drag from the center of mass to another object in the viewports.

    If the object is moving, the biped moves with it; biped animation is now relative to this object. Use this to animate a biped on a ship or train for example.