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Make Wire from Joint Motion
Creates a multi-segmented wire based on the animated motion of a bone. A new segment is generated at the end of each frame; the segment is a straight line between the previous position of the joint and its position at the current frame.
This operation can be used to create "motion wires" which can be used with the IK Move Along Wire operation if you want to "fine tune" the motion capture data.
Figure 3.15 Wires can be generated from any joint on a skeleton
The generated wire is created from the tip of the bone that is further from the root.
The Make Wire from Joint Motion operation should come after the Update Skeleton operation.
Table 3.10 Make Wire from Joint Motion parameters
The Quaternion Rotate Bone operation lets you rotate a bone using "quaternion" notation, which describe the orientation of an object in 3D space using four values rather than three (as with X, Y, Z rotations).
Using a quaternion rotations avoids "gimbal lock" which can sometimes happen when a bone is closely aligned with the global X, Y, or Z axes. Some animators find it easier to use than other rotation commands, since you pose the skeleton and copy the current state of one or more bones into a cue (much like keyframing).
Figure 3.16 Left, original skeleton; right, copy, with upper left arm rotated with Quaternion Rotate Root
To use the Quaternion Rotate Bone operation:
1. Create a Quaternion Rotate Bone channel.
2. Insert a cue where you want the rotation to occur.
3. (CLICK-M) on a cue.
- The following menu appears:
Figure 3.17 Using Quaternion Rotate Root on a bone
4. Rotate the target bone into the desired pose.
5. (CLICK-L) on CopyOrientation.
6. (CLICK-L) on the Animate button in the N-Dynamics script editor.
- The script animates, and the bone rotates, hitting each cue in the channel.
Table 3.11 Quaternion Rotate Bone parameters
Quaternion Rotate Root
The Quaternion Rotate Root operation is similar to the Quaternion Rotate Bone operation described previously. This operation lets you rotate the root of the skeleton using "quaternion" notation, which, as mentioned before, describe the orientation of an object in 3D space using four values rather than three (as with X, Y, Z rotations).
Using a quaternion rotations avoids "gimbal lock" which can sometimes happen when a skeleton is closely aligned with the global X, Y, or Z axes.
Figure 3.18 Left, original skeleton, right, skeleton root rotated on the Y axis with Quaternion Rotate Root
To use the Quaternion Rotate Bone operation:
1. Create a Quaternion Rotate Bone channel.
2. Insert a cue where you want the rotation to occur.
3. (CLICK-M) on a cue.
- The following menu appears:
Figure 3.19 Using Quaternion Rotate Root on a skeleton
4. Rotate the target bone into the desired pose.
5. (CLICK-L) on CopyOrientation.
6. (CLICK-L) on the Animate button in the N-Dynamics script editor.
The script animates, and the bone rotates, hitting each cue in the channel.
Table 3.12 Quaternion Rotate Root parameters
Reads in Acclaim format motion capture data (including the .asf and .amc files). To animate using this operation you need:
To animate a skeleton using this operation, you'll typically include this channel as one of the first skeletal operations in the script; to animate the selected skeleton, use an Update Skeleton operation.
The Read Acclaim Data operation should come before the Update Skeleton operation.
Table 3.13 Read Acclaim Data parameters
Reads in Biovision motion capture data. To animate using this operation you need:
To animate a skeleton using this operation, you'll typically include this channel as one of the first skeletal operations in the script; to animate the skeleton, use an Update Skeleton operation.
The Read Biovision Data operation should come before the Update Skeleton operation.
Table 3.14 Read Biovision Data parameters
Reads a Motion Analysis motion capture data file. To animate using this operation you need:
To animate a skeleton using this operation, you'll typically include this channel as one of the first skeletal operations in the script; to animate the skeleton, use an Update Skeleton operation.
The Read Motion Analysis Data operation should come before the Update Skeleton operation.
Table 3.15 Read Motion Analysis Data parameters
The Rotate Root operation lets you dynamically rotate the root of the skeleton around the X, Y, or Z axes.
Figure 3.20 Using rotate root on a skeleton
As with any dynamic operation, you can specify any number of cues in any channel. You might, for instance, want the skeleton to change its X, Y, and Z rotation at frame about a third of the way into the script, then change its X rotation twice more near the end of the script:
Figure 3.21 Enter cues in the appropriate channel wherever you want the skeleton to rotate
After inserting the cues where you want the rotations to occur, you can edit the cue values:
1. (CLICK-M) on the cue.
2. Adjust the value using the slider.
3. (CLICK-L) on the Animate button.
The following parameters can be set for the Rotate Root operation:
Table 3.16 Rotate Root parameters
Scales the length of the selected bone using the dynamic value in Factor. You can scale the bone using one of the three modes described below. This technique can be used on several bones to create cartoonish effects, as described in the Skeletal Animation System Tutorial.
Figure 3.22 Scaling a bone
- Note. You must make sure that the bone being scaled does not have a fixed length. If the DOF defined for this bone does not allow it to be scaled, the operation executes, but the bone doesn't change length.
To check the DOF for the referenced bone, (SHIFT-L) on the bone in the N-Geometry window and try to resize it using the Scale Bone operation. If the bone has a fixed length, the following dialog box appears:
Figure 3.23 Scaled bones cannot have fixed length
You can (CLICK-L) on Yes to free the bone.
To check the fixed length setting for multiple bones at the same time, (SHIFT-L) on the skeleton and (CLICK-L) on DOF Editor, then make sure the Scale DOF is checked for that bone:
Figure 3.24 Use the DOF editor to set the "scalability" of multiple bones at once; Min and Max values are displayed if the Scale DOF is active
In Figure 3.24, the second bone can be scaled; all others are of fixed length.
Table 3.17 Scale Bone parameters
If you want to transform (move, rotate, or scale) the entire skeleton, you can use the Transform Root operation. This operation is actually performed on the skeleton object.
Figure 3.25 Transforming the Root node
This operation could be used to move the entire skeleton in 3D space, to rotate the skeleton around its root, or scale the entire skeleton object larger or smaller. Note that by default the scale subchannel is not dynamic, although it can be made so. Dynamic channels are created for XYZ rotations and offsets:
Figure 3.26 In a Transform Root operation, rotate and translation channels are automatically dynamic
The following parameters can be set with the Transform Root operation:
Table 3.18 Transform Root parameters
If you want to translate the entire skeleton (move it along one or more axes), you can use the Translate Root operation. This operation is actually performed on the skeleton object.
Figure 3.27 Translating the Root, in this case, along the Z axis
This operation has fewer parameters than the Transform Root operation described earlier; translations do not include scaling or rotation of the target object.
Table 3.19 Transform Root parameters
As mentioned in the section "Skeletal Operation Order in N-Dynamics Scripts," on page 3-2, the Update Skeleton operation applies the changes specified in other skeletal operations to the skeleton.
The Update Skeleton operation is visually divided into several logical sections:
If you do a simple dynamic operation such as Move or Rotate to a skeleton after the Update Skeleton operation, any skins are not updated. Update Skins updates the skins according to the new skeleton position (and should obviously go toward the bottom of the script).
Table 3.21 Update Skin parameters
Writes an .amc file based on the animated motion of a skeleton.
This operation might be used, for example, after you had used the IK Move along Wire operation to tweak a previously saved motion capture (.amc) file. These saved files can then be reread using the Read Acclaim Data operation.
Table 3.22 Write Acclaim Data parameters
- Note. If you write out a frame range of the script, written frames are numbered 1 through N, regardless of their frame number in the script.
Rotates a bone around its local X axis.
Table 3.23 X Rotate Bone parameters
Rotate a bone in any or all three planes. Separate subchannels are created for each dynamic value.
Table 3.24 XYZ Rotate Bone parameters
Rotates a bone around its local Y axis. See X Rotate Bone, above, for details.
Rotates a bone around its local Z axis. See X Rotate Bone, above, for details.
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