rojo/.cursor/rules/roblox/en-us/physics/constraints/align-position.md

title	description
AlignPosition	The AlignPosition constraint applies force to move two attachments together, or to move one attachment to a goal position.

For an overview on creating, visualizing, and simulating mover constraints, including `Class.AlignPosition`, see [mover constraints](../../physics/mover-constraints.md). Also see [Roblox units](../../physics/units.md) to understand how Roblox units compare to metric units.

An Class.AlignPosition constraint applies force to move two attachments together, or to move one attachment to a goal position. As indicated by the name, it only affects the position of the attachments, not their orientation (to align attachments by orientation, see AlignOrientation).

By default, the constraint only applies force to `Class.Constraint.Attachment0|Attachment0`, although this behavior can be controlled through the constraint's [reactionary force](#reactionary-force).

Force location

By default, force is applied to the parent of Class.Constraint.Attachment0|Attachment0 at that attachment's location, meaning that if the parent's center of mass is not aligned with the direction of the force, torque will be applied as well as force. Alternatively, force can be applied to the parents' center of mass by toggling on Class.AlignPosition.ApplyAtCenterOfMass|ApplyAtCenterOfMass.

Force magnitude

You can configure the Class.AlignPosition constraint to apply the maximum force that constraints allow through the Class.AlignPosition.RigidityEnabled|RigidityEnabled property. When true, the physics solver reacts as quickly as possible to complete the alignment. When false, the force is determined by Class.AlignPosition.MaxForce|MaxForce, Class.AlignPosition.MaxVelocity|MaxVelocity, and Class.AlignPosition.Responsiveness|Responsiveness.

Reactionary force

By default, the constraint only applies force to Class.Constraint.Attachment0|Attachment0 while Class.Constraint.Attachment1|Attachment1 remains unaffected. If desired, force can be applied to both attachments in equal and opposite directions by enabling Class.AlignPosition.ReactionForceEnabled|ReactionForceEnabled.

Attachment mode

The Class.AlignPosition.Mode|Mode property specifies whether the constraint uses one or two attachments in calculating its goal. By default, this is Enum.PositionAlignmentMode.TwoAttachment|TwoAttachment, meaning that the constraint disregards Class.AlignPosition.Position|Position and attempts to move Class.Constraint.Attachment0|Attachment0 to the position of Class.Constraint.Attachment1|Attachment1. If set to Enum.PositionAlignmentMode.OneAttachment|OneAttachment, the constraint disregards Class.Constraint.Attachment1|Attachment1 and attempts to move Class.Constraint.Attachment0|Attachment0 to Class.AlignPosition.Position|Position.