Working with the Test Animation
After your initial pass at the envelopes, you can create a test animation for the biped and review the envelope performance. You’ll inevitably find vertices, usually in the hands and feet, that are not assigned or are incorrectly assigned. You can then do manual weighting of the vertices using the 3ds Max 8 Weight Tool to quickly adjust the vertex and bone association.
Create any kind of test animation you like, based on the animation required for your character. If the character is going to be walking, you can use the Footstep animation method is create a fast walk cycle for skinning purposes. If, however, your character needs to raise its hands above its head or do the splits, then you’ll want to create this kind of animation manually using Freeform mode. Or you can also just load in any BIP file to accomplish this motion testing. The footstep motion serves to help you see how the skinning deforms the mesh, any other BIP file with sufficient motion will do the same thing.
Exercise 3.2 Setting Up a Test Walk
In this exercise you’ll set up a walk for use in testing the skinning of the rabbit biped.
- Use the file you’ve been working on, or load Rabbit_skin.max from the CD that comes with the book.
- Press the h key and select the rabbit_lr object. Right-click and choose Properties, and turn off See-Through. Then, in the right-click quad menu, click Hide Selection to hide the display of the rabbit mesh in the viewport.
- Select any part of the biped.
- Go to the Motion panel.
- If necessary, turn off Figure mode and turn on Footstep mode.
- On the Footstep Creation rollout, click Create Multiple Footsteps.
The Create Multiple Footsteps dialog appears.
In later chapters we’ll examine the options in this dialog. For now, we’ll just create a few footsteps.
- Change Number of Footsteps to 8; then click OK to exit the dialog and create the footsteps.
The rabbit has large feet, and the footsteps are quite close together. You can scale the footsteps to better suit this rabbit.
- In the Footstep Operations rollout, use the Scale spinner to lengthen and widen the footsteps.
- Click Create Keys for Inactive Footsteps.
- Play the animation. The biped walks.
- Hide everything in the scene. Then unhide just the rabbit and play the animation again. Now you can see that the skin modifier is driving the animation of the rabbit mesh using the biped’s bones.
- Look for unnatural stretching as the character moves. In our rabbit, check the legs and the feet; they may be influenced by
the envelopes from the spine. Be sure to review the animation from several different views—you’ll be surprised what you find
when you look at it from the side, back, or from underneath.
This rabbit is a round and fat character, and his belly and love handles collide with the arms during the animation. The arms in fact pass through the sides of the rabbit’s hips. This is the fault of the animation, not the skinning.
- Exit Footstep mode. If you want to see a freeform animation instead of using footsteps, unhide the biped and select any biped part. Then in the Biped rollout of the Motion panel, choose Load File.
- Find the rabbit_test_animation.bip file on the CD and load it in. The rabbit raises his toes and hangs from one paw.
In the adjacent illustration, we’ve hidden the biped.