How the player character works¶

The player is one Blueprint: Content/TheLastTemplate/Blueprints/PlayerCharacter/BP_PlayerCharacter. It is a plain Unreal Character. Everything it can do is an actor component sitting on it, and each component owns one system and nothing else.

This page says which component owns what, what drives the animation, and which page to open when you want to change something.

What is on the player character¶

Twelve components carry the gameplay. To change what a system does, open the component, not the character.

Component	What it owns	Where it is covered
`BP_VitalsSystem`	Health, stamina, dying	Health, stamina and new vitals
`BP_CombatComponent`	Melee attacks, dodges, stealth finishers	How melee works
`BP_HitReactionManager`	Physical hit reactions and the ragdoll handover	Tune hit reactions
`BP_FallDamageComponent`	Damage from a fall	Fall damage and death
`BP_FactionComponent`	Who counts as an enemy	Factions and targets
`BP_PlayerWeaponManager`	Guns carried, ammo, the weapon wheel	How guns work
`BP_WeaponUpgradeComponent`	Attachments and weapon upgrades	Add a weapon upgrade
`BP_PlayerThrowableManager`	Throwables and the throw arc	How throwables work
`BP_PlayerInventoryManager`	Backpack, crafting, collectibles	Add an item
`BP_PlayerSkillManager`	Skills and what they buff	Add or change a skill
`BP_PlayerInspectManager`	Holding an object up and turning it	How inspection works
`BP_PlayerPhotoModeManager`	Photo mode	Photo mode

The rest of the components are the rig, not gameplay:

boomTPS and cameraTPS, the camera you play on
boomDeath and cameraDeath, the camera that takes over when you die
lightSocket and BP_SocketLightChild, where the flashlight hangs
BP_MotionWarping, which lets traversal montages land your hands on the real edge

Six camera fields on the character are not the knobs they look like

Spring Arm Value, Spring Arm Value Crouch, Field Of View Camera, Capsule Radius Value, Socket Offset and Socket Offset Crouch all read 0 on BP_PlayerCharacter. They are filled in at Begin Play from the real boomTPS, cameraTPS and capsule components. Typing a value into them changes nothing. Set it on the component instead.

The one animation blueprint¶

One animation Blueprint drives the player, the NPCs and the zombies. Four assets are involved.

Asset	What it is
`Blueprints/PlayerCharacter/Animations/ABP_HumanoidCharacter`	The animation Blueprint on the mesh. It works out speed, angle, gait, aim, overlay and IK, and owns the aim offsets `AO_HumanoidAO` and `AO_WeaponAO`
`Blueprints/PlayerCharacter/Animations/ALI_LocomotionLayers`	The animation layer interface. It is the list of layers `ABP_HumanoidCharacter` links in
`Blueprints/PlayerCharacter/Animations/ABP_LocomotionLayers`	The base layer class. It holds the state machines, plus the lean and narrow passage blend spaces
`Blueprints/PlayerCharacter/Animations/Childs/ABP_LocomotionLayer_Unarmed`	The one child layer that ships. It holds no graph, only the animation assets

The split is the point. ABP_HumanoidCharacter decides what the character is doing. The layer decides which animation plays. So swapping animations means filling in a child layer class, not editing a graph.

How the character talks to the animation blueprint¶

Through Blueprints/Interfaces/BPI_LocomotionGaitInterface, in both directions. Any character that implements the interface can use ABP_HumanoidCharacter.

The character answers Get Gait Data. The animation Blueprint asks for the current gait and its settings.
The character calls Receive Aim State, Receive Overlay State, Receive Locomotion Extras, Receive Doing Traversal Action, Receive Use Overlay, Receive Traversal IK Left and Receive Traversal IK Right on the animation Blueprint when those things change.

BP_NPCCharacter and BP_ZombieCharacter answer the same interface, which is why they share the animation Blueprint with the player.

Turn in place¶

When you move the mouse standing still, the capsule turns at once. The mesh does not follow it. Root Yaw Offset holds the body back so it keeps facing where it was.

Once the offset is wide enough, the layer picks a turn animation and plays it, and that animation drains the offset back to zero through its own curves. Eight animations per stance, at 45, 90, 135 and 180 degrees, left and right:

standing, in Normal Turn In Place Animations, from Demo/Animations/Characters/TurnInPlace/Normal/
crouched, in Crouching Turn In Place Animations, from Demo/Animations/Characters/TurnInPlace/Crouch/

Both are fields on ABP_LocomotionLayer_Unarmed. Root Yaw Offset Mode on ABP_HumanoidCharacter ships as Accumulate, and the other two values, BlendOut and Hold, exist for the moments where the body must stop drifting.

Lean, direction and play rate¶

BS_HumanoidLean in Content/TheLastTemplate/Animations/BlendSpaces/ bends the body into a turn while running. It is driven by Lean Angle, and it is built from five poses in Demo/Animations/Characters/Lean/: base, front, back, left and right.

Direction is four values, not eight. E_LocomotionDirections is Forward, Backward, Right and Left, and the blend spaces cover everything between them. What comes in eight is the stop: Walking Stop Directions, Running Stop Directions and Crouching Stop Directions each hold four directions times which foot is planted, so the character stops on the foot that is down.

The blend spaces that ship:

Blend space	Where it is set
`BS_HumanoidWalking`	`Blendspace Walking` on the child layer
`BS_HumanoidRunning`	`Blendspace Running` on the child layer
`BS_HumanoidCrouching`	`Blendspace Crouching` on the child layer
`BS_HumanoidLean`	inside `ABP_LocomotionLayers`
`BS_HumanoidNarrowPassage`	inside `ABP_LocomotionLayers`

Footsteps¶

Animations/AnimNotifies/Character/AN_FootstepSound is the parent notify. It traces down from the foot, reads the physical material it lands on and plays the matching cue from Content/TheLastTemplate/Audios/Footsteps/. Six surfaces ship: concrete, grass, ground, metal, water and wood. The gait sets how loud it is.

AN_FootstepSound_L and AN_FootstepSound_R are its two children, one per foot. You do not place them by hand: Animations/AnimModifiers/AM_FootstepSounds is an Animation Modifier that adds them to a sequence for you, off the ball_l and ball_r bones.

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