| title | description | author | ms.author | ms.date | ms.localizationpriority | keywords |
|---|---|---|---|---|---|---|
Follow Component |
Guide to Follow, a component used to make an actor follow the user. |
luis-valverde-ms |
luval |
08/25/2020 |
high |
Unreal, Unreal Engine, UE4, HoloLens, HoloLens 2, Mixed Reality, development, MRTK, UXT, UX Tools, follow component, leashing |
The FollowComponent is used to keep objects "following" the user by applying a set of constraints on the component's owner.
Place a FollowComponent on your actor. In this example, we created an empty actor and added some geometry and text to make a panel that we want to keep in front of the user. Since we also want it to always face the user, we've set the "Orientation Type" to "FaceCamera".
Hint: The camera looks down the +X axis, so you may want the front face of your content be in the -X direction.
The FollowComponent has three different constraints that keeps its owner in front of the camera: Angular Clamp, Distance Clamp, and Orientation. The combination of Angular and Distance Clamp creates a frustum in front of the camera where its owner can be. If its owner is outside that frustum it is adjusted.
Angular Clamp: The objective of this constraint is to ensure that the reference forward vector remains within the bounds set by the leashing parameters. To do this, determine the angles between toTarget and the leashing bounds about the global Z-axis and the reference's Y-axis. If the toTarget falls within the leashing bounds, then we don't have to modify it. Otherwise, we apply a correction rotation to bring it within bounds. This will ensure that the its owner stays within the top, bottom, right and left planes of the frustum.
Distance Clamp: The objective of this constraint is to ensure that the following actor stays within bounds set by the distance parameters. To do this, we measure the current distance from the camera to the its owner. If the distance is within the MinimumDistance and MaximumDistance then we don't have to modify it. Otherwise, we push away or pull in the its owner along the reference forward vector. This will ensure that the its owner stays within the near and far planes of the frustum.
Fixed vertical Offset: The objective of this constraint is to ensure the following actor stays at a fixed vertical distance away from the camera. This can be used to ensure the following actor always sits above/below eye level to prevent the actor from obstructing the user's vision.
Orientation: The two options provided are constant FaceCamera or WorldLock. While world locked there are three conditions that will cause the its owner to face the camera: Angular Clamps Distance Clamps The angle between the forward vector of the its owner and toTarget vector (vector between the camera and the its owner) is larger than dead zone angle parameter