The Skin->Deformation Parameters commands in the Actor module allow you to modify the envelope deformation.

The Skin->Inner Side/Outer Side commands allow you to deform the inner or outer part of the envelope. "Inner" and "outer" sides of the envelope correspond to the way the joint bends. For example, on an arm, the inner side is the bicep and the outer side is the tricep. The means of deformation is a curve function, either predefined or user-defined.

You can set various parameters to:

• Control the strength of the deformation (deform it a little or a lot).
• Control where the deformation starts and ends in relation to a joint.

Note:

The associated dialogue box allows you to choose from two predefined curve functions (finger or biceps).

If you want to draw a custom deformation curve, use the Skin->Deformation Curves commands first. You can then set the same type of deformation parameters for your user-defined curve using the Skin->Deformation Parameters commands.

These commands work only on flexible envelopes and skeleton chains or joints: you cannot use them when working with rigid envelopes or objects used in skeletons.

Procedure

1. Select a chain root or joint to which you have already assigned a flexible type of envelope (Automatic, Local, or Global).
2. If you select a chain root, the whole envelope is affected along the inner or outer side of all joints when they bend. If you select a single joint, the envelope is affected by the deformation settings only around the selected joint when it bends.
3. Choose the Skin->Deformation Parameters->Inner Side/Outer Side command.
   
   The Flexible Envelope Parameters dialogue box is displayed.
   
   
4. Set the Beginning and End values to define the start and end points of the deformation. These are expressed as a percentage of the length of the selected joint(s). Beginning 0 to End 100 affects the entire joint until the beginning of the next joint. The value 50 is the midpoint.
5. Select the Type of deformation, if you like.
6. Set the Amplitude (strength) of the deformation.

• 0% amplitude shows no deformation.
• 100% amplitude doubles the thickness of the envelope at the point where the deformation peaks.

7. To exaggerate the deformation more, adjust the Scaling value.
8. Click Ok to accept the settings or Cancel to exit the dialogue box.

You should see a deformation effect immediately, unless the joint is not bent at all. In any case, when you move the effector, the envelope deforms according to the deformation profile and settings.

Parameters

Beginning and End

Defines the start and end points of the deformation, expressed as a percentage of the length of the selected chain or joint.

For example, if you set Beginning to 30 and End to 80, the deformation parameters apply from a point 30% of the way along the joint to a point 80% along the joint. A line graph representing the
x-axis of the chain or joint is displayed above the sliders to help you visualize the deformation area.

Type

No additional deformation is added. Envelope vertices simply follow their assigned skeleton elements, according to the current weighting assignments. This is the default type.

This option is useful if you wish to remove any deformation parameters you have set.

Two predefined deformation types are available: Finger and Biceps. Finger deformation imitates the inside of a finger joint when it is bent. Biceps deformation imitates bulging biceps when an arm is bent.

 

Note:

If a user-defined deformation curve is assigned to the selected chain or joint, these options are dimmed.

You can also create a custom deformation profile using the Skin->Deformation Curves command.

Amplitude

Defines the amplitude (strength) of the deformation inflation. Values range from 0% to 100%. A 0% amplitude shows no deformation, whereas a 100% amplitude doubles the thickness of the envelope at the point where the deformation peaks.

Scaling

Allows you to scale the defined deformation using positive values only. This exaggerates the deformation effect.

Joint Area

The Skin->Deformation Parameters->Joint Area command allows you to control the percentage of the envelope that is affected by rounding as the joint bends. On the envelope, every point whose projection falls within this region of the joint receives a rounding effect.

It is usually best to use values at or near the default value for joint area parameters as follows:

• For joints with Weighted envelopes, 0.0 or low joint area values.
• For joints with Full Weight envelopes, 0.2.

This rounding is most useful for tube-like envelopes assigned with the Full Weight option, in which case you might go as high as 8 or 9 percent. The maximum value is 50%.

You do not need to have assigned an envelope yet, but if you have one, you can see the results on it interactively.

Procedure

1. Select the joint or chain.
2. Choose the Skin->Joint Area command.
   
   The Joint Area Parameter dialogue box is displayed.
   
   
3. Define the percentage of the selected joint or chain that is to be affected by rounding by using the Joint Area slider.
4. Select Auto Refresh to automatically update the scene with the modifications you make. If you like, you can deselect this option and use the Refresh button only when you want to see the changes you have made.
5. Click Ok to accept the settings.

Last updated 02-apr-1998