Get Special Control

The Control->Get Special Control command in the Actor module allows you to incorporate various dynamic forces into your simulation. The dynamic forces are represented by control icons which are null models that can be animated, constrained, and incorporated in a hierarchy like other SOFTIMAGE 3D objects.

The Control->Get Special Control command is used in conjunction with Control->Select.

Procedure

1. Choose the Control->Get Special Control command.
2. Select the desired control from the command list.

The icon representing the control is created and displayed.

Gravity

Gravity vectors are used to apply gravity to an object or chain. The gravity icon (identified with a G) allows you to control the acceleration at which an object falls or moves in the direction of the gravity vector. The default value is earth's gravity, which is numerically set so that the default grid layout in the SOFTIMAGE 3D windows is measured in centimeters. You can modify the strength of the gravity by scaling the gravity vector in the y-direction. The position of the vector relative to the object is not important.

Note:

A gravity control that is assigned to a specific object overrides the default gravity for that object. Two or more gravity controls assigned to an object averages their combined values.

Force

The Force command creates a force icon (identified with an F) that allows you to assign a force to a joint.

You can modify the strength of the force by scaling the force vector in the y-direction. The position of the vector relative to the object is not important. The force is always applied to the object's centre of gravity.

Wind

The Wind command creates a wind icon (a fan) that allows you to assign a directional wind to an object. Set its effect on the object by using the Dynamics->Option Setup command.

You can modify the strength of the wind by scaling the wind icon in the y-direction. The distance of the wind icon relative to the object is not important.

Fan

The Fan command creates a fan icon (a fan with a cone) that allows you to assign a directional fan to an object.

You can define the strength of the wind generated, and the area and distance it affects using scaling as follows:

• x scaling modifies the length of the decay vector. This is the length of the line extending from the fan that defines the farthest point where the fan has an influence. The decay function between the fan and this point is linear.
• y scaling modifies the size of the fan to increase or decrease the air current generated by the fan.
• z scaling modifies the radius of influence of the cone. The radius of the cone defines the area affected by the fan.

Nail

The Nail command creates a nail control that allows you to assign a positional constraint to an individual joint of a chain. The selected joint is attached to the nail. When the chain is in a non-dynamic segment of its transition curve, the nail is considered to be an ordinary spatial constraint (see the Constraint commands starting on Constraint->Position).

You can define the point on the joint where it is attached to the nail and control the stiffness of the nail using scaling as follows:

• x scaling defines the point of attachment.
  • 0.0 x scaling attaches the joint at its origin (like a standard constraint).
  • 1.0 x scaling attaches the joint at its end.
• y scaling controls the stiffness or holding force of the nail. Values range from 0.0 to 1.0. The greater the value, the stronger the attachment.

Negative scaling disables the constraint.

Tip:

Modify the stiffness cautiously because the position of the joint may fluctuate if it is initially far away from the constraint.

Last updated 03-apr-1998