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Make a held item, its hold pose and hand IK

By the end of this page you have an item that appears in the player's hand when its slot is selected. It does its own thing when used. Other players see it held with a proper pose, with the left hand on the grip if it needs one.

If you do not have the item's Data Asset yet, start with Add an inventory item. This page picks up from its Wield Actor Class field.

  • The held actors: Content/MPFriendslop/Blueprints/Environments/Items/Wieldable/
  • Their components: Content/MPFriendslop/Blueprints/ActorComponents/
  • The item Data Assets: Content/MPFriendslop/Blueprints/DataAssets/Item/Childs/

How a held item works

When a slot is selected, the server spawns the item's Wield Actor Class, usually a child of BP_WieldedItem, and attaches it to the player's hand. The held actor carries two copies of the item mesh:

  • ViewMesh, the first person copy. Only its owner sees it, and it follows the camera.
  • HandMesh, the third person copy. Everyone except its owner sees it, and it rides the hand socket.

Both meshes are set on the held actor itself, so its Blueprint viewport shows the item and you place it there. Behaviour is added with components on the held actor: the flashlight has BP_FlashlightComponent, the shotgun has BP_WeaponComponent. BP_WieldedMedkit and BP_WieldedBattery have no graph and no component of their own, because their effect lives on the pawn: they only carry their mesh and its first person placement.

Step 1, make the held actor

Pick the shipped one closest to yours.

Start from Take this one when What it brings
BP_WieldedMedkit The item is a static mesh and needs nothing but to be held Both meshes, the sway
BP_WieldedFlashlight The item gives light and drains a charge A Light spot light, BP_LightComponent, BP_FlashlightComponent
BP_WieldedShotgun The item is a gun, or any skinned mesh that plays its own montages See Add a new gun
  1. In Childs/, duplicate the one you picked. A child of BP_WieldedItem works too.
  2. Name it BP_Wielded<YourItem> and keep it in Childs/.
  3. Select HandMesh, then ViewMesh, and set the Static Mesh of both to your item's mesh.
  4. Add your own components to it.
  5. Open your DA_Item_* and set Wield Actor Class to it.

Place it in first person

Where the item sits in front of the camera is the transform of ViewMesh in the held actor. Select ViewMesh in the Blueprint viewport and move it with the gizmo, or type the values in Details.

Read it as a position from the player's eye, in cm: X forward, Y right, Z up. The Blueprint's origin stands for the camera. A yaw of 90 points a mesh modelled along its Y axis forward.

Item Location Rotation
Flashlight, battery (35, 18, -19) yaw 90
Shotgun (30, 18, -19) yaw 90
Medkit (50, 16, -26) yaw 90

The medkit sits further away and lower because it is a wide box: at the flashlight's place it would fill a quarter of the screen. Compile the Blueprint, then take the item in hand to judge it in game.

The third person copy is placed by the hand socket instead (step 3).

Your own actor instead of a child

Wield Actor Class accepts any actor. The only thing the inventory requires of the held actor is the BPI_Wieldable interface, so an actor with another parent works too:

  1. Open your actor, then Class Settings, and add BPI_Wieldable to Implemented Interfaces.
  2. In Class Defaults, tick Replicates.
  3. Implement the SetWieldedItem event. Its Item Data input is the item's Data Asset, sent right after the actor spawns.
  4. If your actor needs the Data Asset later, store Item Data in a replicated variable: SetWieldedItem runs on the server only. BP_WieldedItem keeps it for hand IK.
  5. Put your meshes on the actor itself.

Such an actor gets none of what BP_WieldedItem does for you: the two meshes, the first person copy on the camera, the sway. Hand IK also comes from BP_WieldedItem. To keep it, implement BPI_HandIK and copy GetHandIKGrips from BP_WieldedItem (step 4).

Step 2, give it behaviour

Gameplay runs on the server. Your component finds BP_InventoryComponent on the player and binds its On Item Used dispatcher behind a Has Authority check. BP_FlashlightComponent does exactly this, so open it and copy the shape.

For an item with a charge (battery, ammo), the charge lives in the inventory slot, not on the held actor:

Function on BP_InventoryComponent What it does Call it on
ConsumeSelectedCharge Takes Amount off the selected slot's charge server
RefillSelectedCharge Fills the selected slot back to Max Charge server
GetSelectedChargeRatio Returns the charge from 0 to 1. An item with Max Charge at 0 returns 1 any machine

The dispatchers a held item can use:

Dispatcher On When Fires on
On Item Used BP_InventoryComponent The player used the selected item every player
On View Attached BP_WieldedItem ViewMesh has been attached to the camera owning player

A child binds On View Attached for its own setup. The flashlight uses it to hook its light onto the first person mesh.

Warning

On Item Used fires on every machine. A listener that changes the game (a charge, a door, damage) without checking Has Authority runs once per player, and nothing tells you. Cosmetic effects, like a sound, can listen everywhere.

The flashlight, as a model

BP_FlashlightComponent toggles the light on use, drains the charge while it is lit, blinks when the charge is low and turns off at 0.

Field What it does Shipped
Drain Per Second Charge taken per second while lit. At 1, a charge of 100 lasts 100 seconds 1
Low Charge Threshold Below this share of the charge, the light blinks 0.2
Turn On Sound Played when the light turns on CUE_Flashlight_Switch
Turn Off Sound Played when the light turns off CUE_Flashlight_Switch

The beam itself is the Light spot light on BP_WieldedFlashlight. Its brightness and blink are on the BP_LightComponent next to it (Strength, Blinking Interval, Blink Randomness). Strength is applied when play starts, so the editor viewport does not preview it. More on that component in Place, switch and make lamps.

First person sway

BP_WieldSwayComponent moves the first person mesh when you look around, walk, strafe, jump and land. It only runs on the owning player's machine.

Field What it does Shipped
Look Sway Gain How much the item tilts when you turn your head 9
Look Offset Cm How far the item slides sideways when you turn your head 3.5
Lean Gain How much the item reacts when you speed up or strafe 8
Walk Bob Cm Height of the walking bob, in cm 1.2
Vertical Gain How much the item moves on a jump, a fall and a landing 0.8
Sway Smoothing How fast the item follows its target, not how far it moves. Higher is snappier 16

Step 3, the hold pose

Other players see the item in the character's hand, with the upper body in a pose made for it. Apart from the socket, all of it is set on the item's Data Asset.

  1. On your character's skeleton or mesh, add a socket on hand_r where the grip should sit. Name it after the item.
  2. In the Data Asset, set Wield Socket Name to that socket.
  3. Set Overlay Pose to an upper body pose holding the item.
  4. If the item is aimed, set Overlay Aim Offset to a 1D aim offset so the torso follows the view up and down.
  5. If both hands hold it, tick Overlay Uses Left Arm.
Field What it does Flashlight Shotgun
Wield Socket Name Socket the held actor snaps to. Empty uses the Wield Socket Name of BP_InventoryComponent, hand_r FlashlightSocket ShotgunSocket
Wield Relative Transform Offset applied after the snap identity identity
Overlay Pose Upper body pose while held. Empty means no pose AS_Robot_Flashlight_Base AS_Robot_Shotgun_Base
Overlay Aim Offset Vertical aim on top of the pose BS_Flashlight_Aim none
Overlay Uses Left Arm Blends the left arm too, for a two handed item off on

The shotgun ships without an aim offset, so with it the torso does not follow the view pitch. Every shipped item puts the grip in the socket and leaves Wield Relative Transform at identity. Do the same, because you can preview a socket on the skeleton.

Two things to know about the sockets. FlashlightSocket is on the skeleton SKEL_Mannequin, so any mesh on that skeleton has it. ShotgunSocket is on the mesh SKM_Robot_Courier only: on your own character mesh, add it yourself. The held actor attaches to the first Skeletal Mesh component of the pawn, so the socket must be on that one.

The pose and the aim offset are blended in by ABP_FriendslopLocomotion. Its Overlay Blend Speed (12) sets how fast the pose blends in and out.

Step 4, hand IK

A two handed item puts the left hand on its grip with IK.

  1. Open the item's third person mesh and add a socket where the left hand grabs it. By default that mesh is the one on HandMesh. If your held actor shows another mesh, override its GetThirdPersonMesh function to return that mesh. The shotgun returns its HandSkeletalMesh, and its socket is LeftHandGrip on SKM_Tool_Shotgun_SawedOff.
  2. In the Data Asset, set Left Hand IK Socket to that socket name.
  3. For the right hand, Right Hand IK Socket works the same way. No shipped item uses it.

Hand IK Blend Speed on ABP_FriendslopLocomotion (12) sets how fast the hand goes on and off the grip.

Warning

Any montage that takes the hands off the item needs BP_HandIKSuspendNotifyState over that stretch. Without it, the left hand stays glued to the grip while the arm plays the animation. It is already on AM_Shotgun_Reload_TPS and on the three AM_Emote_* montages. Add it to your own reload and emote montages.

To sell your new item in the terminal, see Add an item to the shop.

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