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Add a new gun

A gun is three assets: an inventory item Data Asset, a held actor that carries the gun's skeletal mesh, and a weapon Data Asset that holds every number. Copy the sawed-off shotgun for all three. Then give the gun its animation Blueprint, and its fire and reload montages. You get a gun that can be picked up, fired and reloaded, without writing any logic.

If you have not read How weapons work, start there.

  • Weapon Data Assets: Content/MPFriendslop/Blueprints/DataAssets/Weapon/Childs/
  • Held actors: Content/MPFriendslop/Blueprints/Environments/Items/Wieldable/Childs/
  • Item Data Assets: Content/MPFriendslop/Blueprints/DataAssets/Item/Childs/

Before you start

You need two meshes of your gun:

  • a skeletal mesh, held in the hand, with two sockets: Muzzle, where the shot and the flash leave, and LeftHandGrip, where the left hand holds it. SKM_Tool_Shotgun_SawedOff has both.
  • a static mesh, used by the pickup on the ground. The shotgun's is SM_Tool_Shotgun_SawedOff.

The shotgun's sounds, effects and camera shake can be borrowed while you get the gun working.

Step 1, the weapon Data Asset

  1. In Blueprints/DataAssets/Weapon/Childs/, duplicate DA_Weapon_Shotgun_SawedOff.
  2. Name it after your gun, for example DA_Weapon_Rifle.
  3. Open it. Every field already holds a working value, so you replace rather than fill in.

Fire

Field What it does Shotgun
Fire Mode Single, Burst or Auto Single
Rounds Per Minute Fastest rate of fire. The server refuses shots that come faster 200
Burst Count Shots per trigger pull in Burst 3
Pellets Per Shot Traces per shot. 1 for a rifle or a pistol 8
Spread Degrees Half angle of the cone each pellet lands in 5
Range Trace length, in cm 3000
Damage Per Pellet Damage of each pellet that hits 9
Ammo Per Shot Charge taken from the slot per shot 1

Burst and Auto are built in, but no shipped gun uses them, so the shotgun is your only example.

Fire animations

Field What it does Shotgun
Fire Montage FPS Plays on the gun mesh in first person, for the shooter, on every shot AM_Shotgun_Fire
Fire Montage TPS Plays on the character body, in the UpperBody slot, for every player AM_Shotgun_Fire_TPS
Fire Montage World Plays on the gun mesh the other players see AM_Shotgun_Fire_World

Leave any of the three empty and that view simply has no fire animation. The shooter plays the FPS montage at once, with the flash and the recoil. The other players play theirs when the server confirms the shot.

Reload

Field What it does Shotgun
Reload Seconds Time before the slot is refilled 3.2
Reload Montage FPS Plays on the gun mesh in first person, for the shooter AM_Shotgun_Reload
Reload Montage TPS Plays on the character body, in the UpperBody slot AM_Shotgun_Reload_TPS
Reload Montage World Plays on the gun mesh the other players see AM_Shotgun_Reload_World

Recoil, effects and audio

Field What it does Shotgun
Recoil Pitch How far the view kicks up per shot 4
Recoil Yaw Random sideways kick, left or right 1.2
Recoil Recovery Speed How fast the view comes back down 6
Camera Shake Shake played on the shooter's camera CS_WeaponFire
Muzzle Socket Name Socket the flash spawns on Muzzle
Muzzle FX Niagara system at the muzzle NS_Shotgun_Fire
Impact FX Niagara system where a shot lands NS_Weapon_Impact
Fire Sound The shot CUE_ShotgunFire
Dry Fire Sound The click when the gun is empty, heard by the shooter only CUE_DryFire
Impact Sound Played where a shot lands CUE_Impact_Metal

Two things are set outside the Data Asset. The strength of the shake is on CS_WeaponFire in Blueprints/Effects/. Duplicate it if your gun should kick differently. How far away the shot is heard comes from the attenuation ATT_Weapon_Fire in Audios/Attenuation/.

Step 2, the gun's animation Blueprint

The gun mesh plays its own reload and fire montages, so it needs an animation Blueprint on its skeleton.

  1. Open Blueprints/Environments/Items/Wieldable/Animations/ABP_Shotgun. Its whole graph is a Slot 'DefaultSlot' node into the output pose.
  2. Create an animation Blueprint for your gun's skeleton and build the same graph.
  3. Make your FPS and World montages, reload and fire, on your gun's skeleton, in DefaultSlot.

The TPS montages play on the character, so they are made on the character's skeleton, in the UpperBody slot.

Step 3, the held actor

  1. In Wieldable/Childs/, duplicate BP_WieldedShotgun and name it, for example BP_WieldedRifle.
  2. Select ViewSkeletalMesh and set its Skeletal Mesh Asset to your gun and its Anim Class to your animation Blueprint.
  3. Do the same on HandSkeletalMesh.
  4. Select BP_WeaponComponent and set Weapon Data to your Data Asset from step 1.
  5. Select ViewMesh and move it until the gun sits right in first person: ViewSkeletalMesh follows it. The shotgun's is (30, 18, -19) with a yaw of 90, read from the player's eye (X forward, Y right, Z up).

Duplicate the shotgun rather than making a child of BP_WieldedItem. BP_WieldedItem shows the item's static mesh in the hand. BP_WieldedShotgun is already set up to hide it and show the skinned meshes instead.

ViewSkeletalMesh is the first person copy only the shooter sees. HandSkeletalMesh is the copy every other player sees. The flash is played on whichever one the viewer can see, which is why both need the Muzzle socket.

Step 4, the item Data Asset

  1. In Blueprints/DataAssets/Item/Childs/, duplicate DA_Item_Shotgun_SawedOff.
  2. Set Display Name, Icon and World Mesh (your static mesh).
  3. Set Wield Actor Class to your held actor from step 3.
  4. Set Max Charge to the size of the magazine. The shotgun's is 2: two shells.
  5. Set the hold pose and the hand IK, as in Make a held item, its hold pose and hand IK. Keep Left Hand IK Socket on LeftHandGrip if your mesh uses that name.

Ammo is the slot's charge. Each shot takes Ammo Per Shot from it, and a reload fills it back to Max Charge. There is no ammo item and no reserve to manage.

Use Type stays on Use: firing is an item use.

Step 5, put it in the game

  • In the level: drag BP_ItemPickup in, set Item Data to your item and Charge to the rounds it starts with (2 for a loaded shotgun).
  • In the shop: see Add an item to the shop. A gun bought in the shop arrives full.

Fire is the item use key, Right Mouse (IA_UseItem). Reload is R (IA_Reload). Players rebind both in the CONTROLS tab. To change the shipped keys, see The controls, and adding an input.

To turn a prop into a club instead, see Turn any grabbable object into a melee weapon.

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