From BlenderWiki
Introduction
For a long time, Blender had no mechanism by which the transformations of objects/bones could be clamped to user-defined ranges. Only a few releases ago, Blender got transform locks, which prevented the value of certain transform channels changing.
Transform Limiting Constraints fill in this void. Limit Location, Limit Rotation, and Limit Scale constraints, allow the selective clamping of transform channels to minimums and maximums. They can also be turned on and off by adjusting the influence of the constraint.
Being able to set limits on the range of motion able to be performed by an object/bone is especially important for riggers when rigging characters for animators. By setting limits on the transformations the object/bone is able to perform, it becomes more difficult for the animator to `break' the rig (i.e. pose it in ways which cause ugly distortions or un-intended positions), and also helps regulate the rig's behaviour.
Common Interface
All three constraints share a similar interface.
- For each axis (X, Y, Z) there are two toggle->value pairs.
- One of these controls the minimum value for that axis, and the other controls the maximum.
- The toggle determines whether the value it is attached to gets enforced.
Specifics of each constraint
Limit Location
As the name implies, the Limit Location constraint limits the location of the owner of the constraint to the defined ranges along each axis.
In most situations, there is an extra setting to control which co-ordinate space the limits specified apply to.
- Un-Parented Object:
No extra setting. Limits are relative to the world origin (i.e. where the x/y/z axes meet).
- Parented Object:
`Local' option defines whether limits are relative to the parent object's center instead of the world origin.
- Bones:
`Local' option defines whether limits are relative to the bone's rest-position or not.
Limit Rotation
The Limit Rotation constraint limits the rotation of the owner of the constraint to the defined ranges around each axis.
Only when the constraint is applied to a bone, there is an extra setting. This setting, again named Local, defines whether the limits are around bone's axes in bone-space.
Limit Scale
The Limit Scale constraint limits the scaling of the owner of the constraint to the defined ranges along each axis.
Only when the constraint is applied to a bone, there is an extra setting. This setting, again named Local, defines whether the limits are along bone's axes in bone-space.
In CVS since September 2006 (i.e. Blender 2.43) Developed by Joshua Leung
