INSIDE 3DS MAX® 7 [Electronic resources] نسخه متنی

1.

Start or reset 3ds max. In the Create panel, click Systems (Figure 15.38) and then Biped.

2.

In the center of the Perspective viewport, drag upward to create a Biped about 72 units high (Figure 15.39).

Note

By default (in the United States), a system unit in the 3ds max measurement system is equal to an inch, so this figure is about 6 feet tall.

3.

Go the Motion panel, and in the Biped Apps rollout, click the Mixer button. This opens the Motion Mixer dialog (Figure 15.40). In the dialog, you can see a single track for the Biped, named Bip01. As you'll see shortly, you can do quite a bit with this one track.

First you'll set a few options so you see the same thing as what's shown in this section. Click the Preferences button; it's the second button from the right end of the toolbar. In the Mixer Preferences dialog, in the Clips group, turn on Scales if necessary. Also, in the Other group, turn off Balance Curves if necessary. Click OK to close the dialog.

4.

Position the mouse cursor over the track so it resembles a cross, and then right-click and choose New Clips > From Files.

5.

You'll start with a clip of a Biped walking backwards. From the project folder for this chapter on the accompanying DVD, open the walk_backward.bip file. The clip appears in the Motion Mixer window, but it doesn't quite fit at the default zoom level.

Note

When you load a clip, Motion Mixer assigns it a random color. You can change all of a Biped's clips to another color with the Track Color command, available from the Biped menu.

6.

On the Motion Mixer toolbar, click the Zoom Extents button (Figure 15.41).

You can now see that the clip is 108 frames, a bit longer than the default 3ds max animation length of 100 frames. Unlike the standard Biped function (Load File), opening a clip in Motion Mixer doesn't automatically adjust the overall animation length. In a little while you'll repeat this clip, so you might as well make the animation a lot longer now.

7.

Near the bottom right of the max window, click the Time Configuration button. In the Time Configuration dialog, set Length to 500, and then click OK to close the dialog.

8.

Play the animation. The Biped walks backward for 108 frames and then stops. You needn't wait for the program to play all 500 frames to continue.

9.

Click Go To Start to stop and rewind the animation.

The instruction "play the animation" assumes that you then click Go To Start to stop and rewind the animation.

1.

Near the top left corner of the track, right-click the word All, and from the menu that appears, choose Filter (Figure 15.42). This opens the Trackgroup Filter dialog, which controls which parts of the Biped the tracks in the current group control. By default, it controls all available parts. Note that parts not present in the Biped, such as the tail, appear in the dialog but can't be activated.

2.

Click the None button to turn off all the parts, and then click the Legs button to activate just the right and left legs and feet (Figure 15.43). Click OK to accept the change and close the dialog.

Note

The Trackgroup Filter dialog is modal, so you can't do anything else in the program while it's open.

3.

Play the animation and then rewind it when the motion stops. The legs and feet move as before, but the Biped stays where it is. That's because all the movement buttons are off.

4.

Reopen the Trackgroup Filter dialog. You can now see the Movement Filter buttons; they're the three arrow buttons under the big Spine button. From left to right, they filter horizontal, rotational, and vertical movement.

5.

Click the Horizontal movement button to turn it on, and then click OK and play the animation (Figure 15.44). Now the Biped travels backward again, but there's something a little different about its motion.

6.

Play it again in the Left viewport (adjust the zoom if necessary), and watch the pelvis. The pelvis travels in a completely straight horizontal line, because the vertical motion created by the original walk animation is still filtered out.

7.

Turn the vertical Movement Filter button back on and play the animation again in the Left viewport. Now the pelvis travels up and down as the Biped walks, creating a more natural-looking motion.

Note

The walk motion was created by using the standard Biped function Create Multiple Footsteps and then moving the footsteps behind the character. The Footsteps functionality in Biped is dismissed as a crutch by many animators, but it can be a valuable starting point for many animation tasks.

Before leaving the Filter function, you'll try one last experiment.

8.

Use the Trackgroup Filter dialog to turn off the Left Leg and Foot, close the dialog, and then play the animation. The Biped walks backward using only its right leg and foot. Not too realistic, but somewhat humorous. Before continuing, reopen the Trackgroup Filter dialog and click All to turn all the body parts back on.

1.

Continuing from the previous tutorial, right-click the walk_backward_1 clip and then choose Tile Range. Click Zoom Extents on the Motion Mixer toolbar to see all the copies (Figure 15.45). Motion Mixer has made as many copies as it can fit within the 500-frame animation length and placed them end to end in the current track.

2.

Play the animation. The Biped repeats the backward walk all right, but when it gets to the end of a clip, it just jumps back to the starting point again, instead of continuing to walk backward from the current location. That's not quite what we had in mind. You'll use Motion Mixer's transition track functionality to make it right.

3.

Press Control-Z to undo the Tile Range command, and then right-click the track (not the clip) and choose Convert To Transition Track. The transition track lets you sequence animation segments along the timeline and automatically creates transitions between them so that the motion continues smoothly.

The walk_backward_1 clip now appears at the bottom of the transition track, with brackets above it. These brackets determine the amount of overlap between this clip and the one to which it transitions. In this case, the clip will transition to a copy of itself. You'll use the default transition length.

4.

Right-click the track to choose New Clips > From Reservoir, and open the walk_backward.bip clip again. The Reservoir lets you easily reuse any existing clips in Motion Mixer. Motion Mixer places the new clip in the upper part of the Trackgroup, slightly overlapping the first clip. It also creates a transition, which is the darker bar between the two clips. This is where the software changes over from the first clip to the second (Figure 15.46).

5.

Play the animation; if necessary, adjust the viewport so you can see the whole thing. The first thing you'll notice is that the Biped doesn't return to its starting point before executing the second clip, which is what we wanted. You might also notice that there's a pause during the transition. You can fix this easily.

6.

Right-click the transition, and then choose Optimize. In the Transition Optimization dialog, click OK to accept the default settings and perform the optimization.

Now, when you play back the animation, the pause is gone. Pretty slick! And now for an even slicker trick:

7.

Right-click the transition again, and then choose Convert to Loopable Clip. A loopable clip is one that ends at a pose very close to that of the starting pose, so you can tile it without any glitches in between. It's the animation equivalent of a seamless texture.

8.

The program opens the Save As dialog and prompts you for a file name. Change the file name from the default, clip00.bip, to walk_backward_loopable.bip and then click Save. The two clips are modified and the transition is deleted, creating a new, loopable clip.

9.

Finally, right-click the second, upper clip and choose Tile Range.

1.

Reset or start 3ds max, add a Biped, then go to the Motion panel and open Motion Mixer.

2.

Add the walk_backward.bip file to the available track, as before.

3.

In Motion Mixer, under the Bip01 label, right-click the All label and choose Add Trackgroup Below. A new Trackgroup appears (Figure 15.47).

Note

You can use multiple Trackgroups to control a Biped, or combine tracks in a single Trackgroup; how you group the tracks is up to you. One difference is that you can collapse a Trackgroup by clicking the (minus sign) button next to the Filter label ("All"by default), but you can't collapse individual tracks.

4.

Into the new Trackgroup, import the walk_forward.bip file.

5.

Click the Zoom Extents button on the Motion Mixer toolbar so you can see all of both clips. The walk_backward clip is a bit longer. Make sure the Scales box is checked in the Mixer Preferences dialog.

6.

Drag the right ends of both clips to the 100-frame mark. Note that each track's label changes to reflect its scaling. The upper track is 93 percent of its original length, while the lower track is 8 percent longer than before.

7.

Play the animation. The Biped walks backward, as if the walk_forward clip didn't exist. Given two or more tracks with a weight of 1.0 (100 percent) affecting the same body parts, the uppermost track always takes hold.

1.

At the left end of the first clip, click the "m" button (Figure 15.48). In this case, "m" stands for "mute," which works the same way as the Mute button in an audio-editing program: It temporarily turns off the track. Now, when you play the animation, the Biped walks forward, because only the second clip is in effect.

2.

Click the "m" button again to turn it off, and then click the second track's "s" button. To continue with the audio-program metaphor, "s" (for "solo") allows only the second track to control the Biped. Try clicking the upper "s" button and then the lower one again; they turn each other off. You can mute any number of tracks, but only one can play a solo.

3.

Play the animation. Again, only the forward motion takes hold.

4.

Click the lower track's "s" button again to turn off Solo mode.

1.

Start by setting both weighting values to 0.5 (Figure 15.49).

The black line that previously ran across the top of each clip now starts at the vertical center of the left end of its clip and travels diagonally to the top of the right end. This line depicts how the Weight value changes over time (Figure 15.50).

2.

Play the animation. The Biped starts walking backward slowly and then gradually accelerates to the full speed of the first clip. You'll see why this happens in a moment.

3.

At the right end of the first clip, click the "w" (Edit Weight Curve) button. The weighting line turns red to show that you can now create and edit different Weight values over the course of the animation. Also, the numeric value field for Weight becomes blank, because no vertices on the line are active.

At this point, you can edit anywhere on the line except the start point; to access the first point, you have to turn off the "w" button.

4.

Position your cursor over the red dot at the right end of the red line and click. The red dot turns white, and its Weight value appears in the numeric field. You can now edit this value, either by dragging the dot vertically or by editing the numeric field.

5.

Set both Weight endpoints of each track to 0.5, and then turn off the "w" buttons.

Tip

You can toggle all tracks' Edit Weight buttons by clicking the "w" button at the right end of the Motion Mixer toolbar. To select multiple weighting vertices, drag a rectangle over them.

The black lines are now horizontal, showing that both clips' Weight values are 0.5 throughout the animation (Figure 15.51). Can you predict the effect this will have?

6.

Play the animation. The Biped walks slowly backward, with much sliding of feet. This happens because the distances traveled in the backward and forward walk animations are mostly canceling each other out. However, because the backward walk motion contains more footsteps, it overrides the forward motion slightly. If both had the same number of steps, the Biped would walk in place.

1.

Turn on both Edit Weight Curve buttons again, and then position the mouse cursor over the center of the weighting line in the upper clip (Figure 15.52). The mouse cursor image becomes a thin, downward-pointing arrow with a starburst at the end.

2.

Click and then drag in any direction. When you click, a new vertex appears at the cursor location and then follows the mouse when you drag. You can move it anywhere between the two existing vertices, within the limits of the clip.

3.

Position the vertex at the top of the clip at about frame 33, and then click in an empty area to deselect it.

4.

Add three more vertices as shown in Figure 15.53. Remember to deselect each vertex after adding it so you don't accidentally move it when adding another.