logic_measure_movement

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January 2024

Class hierarchy
CLogicMeasureMovement ↳CLogicalEntity ↳CServerOnlyEntity ↳CBaseEntity
logic_measure_movement.cpp

logic_measure_movement is a point entity available in all Source games. This entity measures the movement of an entity relative to another entity and then applies that movement to a third entity.

logic_measure_movement's process can be described like this:

1. The position of the Entity to Measure is obtained. Let's say it's [100 225 0].
2. The position of the Measure Reference is obtained. Let's say it's [50 300 0].
3. The position of the Entity to Measure is subtracted by the position of the Measure Reference, creating a "relative position" difference. In this case, it would be [100 225 0] - [50 300 0], which equates to [50 -75 0].
4. The position of the Movement Reference is obtained. Let's say it's [150 50 100].
5. The "relative difference" position is added onto the position of the Movement Reference. In this case, it would be [50 -75 0] + [150 50 100], which equates to [200 -25 100].
6. The Entity to Move is teleported to the sum of the "relative difference" position and the position of the Movement Reference, which in this case means the entity is teleported to [200 -25 100].

logic_measure_movement is very flexible and can be used to make one entity mimic the movement of another from another room (e.g. a point_camera in a script_intro). It can also be used to serve as an alternative to parenting, especially since it can simulate parenting on physics objects, which don't support parenting and would normally use phys_constraint.

Warning:Does not properly update collision physics on the object being moved.

Code:By default, logic_measure_movement calls SetAbsOrigin directly. Using Teleport instead updates entity interpolation correctly and may or may not solve the collision physics warning described above.

Keyvalues

Entity to Measure (MeasureTarget) <targetname>

Entity whose movement you want to measure.

Measure Reference (MeasureReference) <targetname>

The movement of Entity to Measure will be measured relative to this entity.

Entity to Move (Target) <targetname>

This entity will be moved to mimic the motions of Entity to Measure.

Movement Reference (TargetReference) <targetname>

The Entity to Move will move relative to this entity.

Movement scale (TargetScale) <float>

A scale to divide the measured movements by, before applying those movements to the Entity to Move.
1 = target entity moves as much as the measured entity,
2 = target entity moves half as far as the measured entity, and
0.5 = target entity moves twice as far as the measured entity.

Measurement Type (MeasureType) <choices>

What to measure.

• 0 : Position
• 1 : Eye position

Name (targetname) <string>

The name that other entities refer to this entity by, via Inputs/Outputs or other keyvalues (e.g. parentname or target).
Also displayed in Hammer's 2D views and Entity Report.

See also:  Generic Keyvalues, Inputs and Outputs available to all entities

Inputs

SetMeasureTarget <string>

Set the Entity to Measure, whose movement should be measured.

SetMeasureReference <string>

Set the Measure Reference entity.

Target <string>

Set the Entity to Move, which will be moved to mimic the measured entity.

SetTarget <string> !FGD

Set the Entity to Move, which will be moved to mimic the measured entity.

SetTargetReference <string>

Set the Movement Reference entity.

SetTargetScale <float>

Set the scale to divide the measured movements by.

Enable

Enable the logic_measure_movement.

Disable

Disable the logic_measure_movement.