In this lesson, you complete the first step by moving the biped body forward and its right foot to the contact position.

Set up the scene

• Continue from the previous lesson.

Lift the foot off the ground:

When the foot lifts off the ground completely, you’ll set a free key.

1. Drag the time slider to frame 15.
2. In the Left viewport, right-click the foot and choose Move from the quad menu. Move the foot up off the ground and forward.

   

   By moving the foot, you are seeing an example of Biped’s IK system. You are creating rotations for the upper and lower leg links as you move the foot.

3. On the Key Info rollout, click (Set Free Key) to keyframe the lifted position of the foot.
4. Scrub the time slider back and forth to observe the animation so far.

Lock down the opposite foot:

1. Drag the time slider back to frame 0 and select Bip01 L Foot.
2. On the Key Info rollout, click (Set Key).
3. Click (Set Planted Key) to set an initial key for the left foot at frame 0.

   This key locks down the foot for any subsequent movement in upcoming frames. If you were to grab the center of mass and move it down, both legs would bend instead of moving below the ground plane.

4. Turn on Select Pivot and pick the pivot point at the ball of the foot.

   

   The left foot with a new pivot point.

5. Click Select Pivot to turn it off.

Keyframe the center of mass:

1. On the Track Selection rollout, click (Body Horizontal).

   Bip01 is automatically selected.

2. At frame 0, click (Set Key) for Bip01.

   This creates a start key for the center of mass.

3. Drag the time slider to frame 15.
4. In the Left viewport, use the Move Transform gizmo to move the center of mass so the torso shifts forward, and then set another key.

   

   Note Because the center of mass is the root node, you can use only Set Key, not the specialized IK keys.
5. Use the Move Transform gizmo to move the center of mass down a little, so the left knee bends slightly, then set another key.

   The left leg bends automatically as the center of mass moves down.

   

6. Select Bip01 L Foot.
7. On the Key Info rollout, set a planted key for the ball of the foot.
8. Right-click the left foot and choose Rotate from the quad menu. Rotate the foot so the heel is lifting up off the ground, and then set another planted key.

   The heel is rotated off the ground.

   

9. Drag the time slider to frame 22, and click (Set Key).
10. Right-click the Perspective viewport, turn on Select Pivot, and then pick the pivot at the end of the toes of Bip01 L Foot.
11. On the Key Info rollout, click (Set Sliding Key), then turn off Select Pivot.
12. In the Left viewport, rotate the left foot up a little more, and set another sliding key.

    

13. On the Track Selection rollout, click (Body Horizontal). Move the center of mass forward again, and set a key.

    

Keyframe the right heel hitting the ground:

1. At frame 22, select Bip01 R Foot and move it forward, then set a sliding key.

   

2. Turn on (Select And Rotate), note the location of the gizmo intersection, and then turn on Select Pivot (this tuns off Select And Rotate). Pick the point at the ankle that lay at the gizmo intersection, and then set a sliding key.
3. Turn off Select Pivot. Rotate the foot so it's parallel to the ground, and then set a sliding key.

   

4. Turn on Select Pivot, and set the pivot to the heel. Set another sliding key.

   

   The pivot point moved to the heel.

5. Turn off Select Pivot. Drag the time slider to frame 27.
6. In the Left viewport, move the right foot forward a little.

   Notice that the foot moves away from the pivot point in the viewport.

   

   Sliding Key lets foot move away from pivot.

7. Set a sliding key.

   The pivot point in the viewport moves to the heel of the foot.

8. Move the right foot down so it touches the ground, and set another sliding key.

   

9. Turn on Select Pivot. Pick the pivot at the ball of the right foot.

   

   The pivot moved to the ball of the right foot.

10. Click (Body Horizontal), move the center of mass so that it is over the heel of the right foot, and set a key.

    

11. At frame 27, select Bip01 L Foot and set a free key.
12. Scrub the time slider and watch the animation of the foot and the pivot points.

Save your work:

• Save the scene as walkcycle_1step.max.