To make the revolving door spin, first you'll link the four doors to the hub. Then, using the time slider, you'll animate the rotation of the hub to spin the doors.

Set up the lesson:

• Continue from the previous lesson, or open start_door_link.max in the \startup folder.
  NoteIf you see the File Load: Units Mismatch dialog, choose the default option: Adopt The File's Unit Scale.

Link the doors to the hub:

1. In the Perspective viewport, zoom so you have a close-up view of the hub and the four doors. It might help to pan and orbit the view, as well.
   
2. On the toolbar, click (Select And Link).
3. In the viewport, drag from one of the pivot door objects to the hub. You will see a dotted line drawn between your cursor and the original door as you drag. Release the mouse over Cylinder01. Cylinder01 should highlight briefly to show it has been linked.
4. Repeat step 3 for each of the other three doors.
5. Click (Select Object) to deactivate Select And Link.
6. To verify that you correctly linked the four doors to the hub, do the following:
   1. Click (Select By Name), or press H on the keyboard.
   2. On the Select From Scene dialog, choose Display Display Children, and then if the Cylinder01 object node is collapsed, click to expand it.

      In the list, all four Pivot Door objects should be indented as children of the Cylinder01 object.

      

      If the list doesn’t appear like this, link the doors that don't appear as children of Cylinder01 to the hub again.

   3. Close the Select From Scene dialog.

      Now you are ready to animate the revolving door.

Replace the rotation controller:

3ds Max Design performs animation by means of software devices called controllers that are assigned to individual objects. Typically an object has three types of controllers assigned: for position, rotation, and scale. The default rotation controller is good for character animation, but you'll replace it with a controller that is better for mechanical aimation.

1. Select the hub, Cylinder01.
2. Go to the Motion panel and expand the Assign Controller rollout.
3. In the Assign Controller window, click to highlight the Rotation: Euler XYZ item.
   
4. Click (Assign Controller).
5. On the Assign Controller dialog, click TCB Rotation, then click OK.
   

   The rotation controller listed in the Assign Controller rollout changes to TCB Rotation.

   

   TCB stands for Tension, Continuity, Bias.

6. Scroll down to the bottom of the Key Info rollout and turn on Rotation Windup. This will allow you to set rotation keys greater than 180 degrees.
   
   ImportantYou must turn on Rotation Windup, or the animation won't work correctly.

Animate the hub:

1. Turn on (Auto Key).
2. Drag the time slider to frame 100.
3. Click (Select And Rotate), then click the hub.
   
4. Rotate the hub 360 degrees about the Z axis. Watch the coordinate display to get the correct rotation.
   TipTo make setting rotations easier, turn on Angle Snap by pressing the A key.

   The Time Slider now shows keyframes as small squares at the beginning and at the end of the time segment.

   

   Rotation key at frame 100

5. Turn off (Auto Key).
6. In the animation playback controls, rewind the animation by clicking (Go To Start), and then click (Play Animation).

   Watch your revolving door rotate in the viewport.

7. Click (Stop, in the same location as the Play button) when you are done watching the animation.

Slow down the animation:

To slow down the rotation of the revolving door, do the following:

1. Click (Time Configuration).

   3ds Max Design opens the Time Configuration dialog.

   
2. In the Animation group, click Re-scale Time.
   
3. On the Re-scale Time dialog, change End Time to 200, then click OK.
   
4. Click OK to close the Time Configuration dialog.

   The Time Slider now displays 200 frames, with a key at frame 0 and frame 200.

5. Click (Play Animation) and watch the revolving door go around.

   The animation plays more slowly than before.

6. Stop the playback.

Save your work:

• Save the scene as as my_revolving_door_animated.max.