GAS, Animation & Input

V5 is one open-world narrative game that has to play like seven. A Hong Kong triad brawler diving into sticky cover, a 1947 detective thumbing a period sidearm, a 1899 outlaw fanning a revolver, a Witcher coating a silver sword in specter oil, a sci-fi marine snapping to a zero-G firing stance, a steampunk gadgeteer, and a cross-cell Mind Palace deducer all run on the same shared gameplay foundation — the same attribute machinery, the same animation catalog, the same input-context model — and differ only in which cell they are mounted as. That partitioning is the job of the four modules this page covers: V5Gameplay (the Gameplay Ability System layout), V5Combat (the third-person gunplay verbs that ride the GAS attributes), V5Animation (the motion-matching and AnimBP pipeline), and V5Input (the Enhanced-Input context model). The join key that stitches them together is one enum, EV5Cell (V5Core/Public/V5Types.h:7): Urban, Period, Frontier, Hunter, SciFi, Steampunk, MindPalace — seven values, not five, because the DLC Steampunk cell and the Mind Palace meta-layer carry tags and data even though only five cells ship combat at launch.

Unlike V5's per-cell ruleset plugins, this layer is cross-cell shared by construction: the modules forbid per-cell dependencies and key everything on EV5Cell so a new cell is a new enum arm plus data, not a fork. This page is part of the Shared Gameplay Foundations group; the section hub is ../V5_ARCHITECTURE.md.

What ships, honestly#

These four modules are real, building Unreal C++ with domain-specific math and genuine automation tests — not skeletons. But they sit at different distances from the engine's runtime, and the honest distance matters. Five qualifications, so the rest of the page reads at face value:

1. GAS is the most engine-integrated of the four. V5Gameplay links the real GameplayAbilities and GameplayTags modules (V5Gameplay.Build.cs), ships four concrete UAttributeSet subclasses and twenty concrete UGameplayEffect subclasses with modifiers configured in C++, and the V5.Gameplay.GE.* specs spawn the engine's real AAbilitySystemTestPawn into a UWorld, apply effects, and assert computed attribute values (V5GameplayEffectTests.cpp:27-97). These would fail against placeholders.

2. There is no central GAS pawn or ASC subclass in this layer. V4 had an AV4Pawn_Operator that owned a UV4AbilitySystemComponent, mounted one attribute set per cell, and switched cells by overwriting that pointer. V5 ships no equivalent — V5Gameplay provides the attribute sets, the gated ability base, and the effects as reusable building blocks, and the only place an ASC is wired to a set is the test (engine AAbilitySystemTestPawn + AddSpawnedAttribute, V5GameplayEffectTests.cpp:29-32). The pawn that mounts a set, grants abilities, and flips cells at runtime is an integration site this module does not contain.

3. V5Gameplay ships zero concrete abilities. The architecture lists ability families (V5_Ability_Sign_*, V5_Ability_DeadEye, V5_Ability_Biotic_*). In the shared module the only ability class is the abstract UV5_GameplayAbility_Base (V5GameplayAbilityBase.h:9); the cell verbs live in per-cell modules, not here. Treat the families as the contract the base enforces, not as classes in this module.

4. V5Animation and V5Input link no engine animation/input plugins. Both V5Animation.Build.cs and V5Input.Build.cs depend on only Core/CoreUObject/Engine/Json/JsonUtilities/V5Core. They do not link PoseSearch, MotionWarping, Chooser, or EnhancedInput. So their IK solvers, motion-match scoring, chooser selection, and IMC-stack swaps are honest standalone C++ computations and content-catalog validators — not calls into UE's Motion Matching / IKRig / Enhanced Input runtimes. The SimulatedLatencyMs field on the IMC swap result (V5InputTypes.h:138) is the honest tell: it is an arithmetic estimate, not a measured frame cost.

5. There are zero binary .uasset files in V5/ue/Content. What ships instead are large, real JSON catalogs the loaders parse and validate — the animation catalog alone is Content/V5Animation/Data/animation_catalog.json at ~390k lines (30,000+ clips). No compiled AnimBlueprint, pose-search database, IKRig, montage, or GameplayEffect .uasset exists for the soft names to resolve to.

Everything below is real where it cites a function and a line; where it names an authored asset or an engine plugin runtime, that is the specified-but-pending part.

GAS layout — attribute sets, a gated base, real effects#

Four attribute sets, 44 replicated fields#

Every stat the game tracks lives in one of four UAttributeSet subclasses, each declared with the V5_ATTRIBUTE_ACCESSORS macro (V5AttributeSets.h:8) that synthesizes the GAS getter/setter/initter quartet. Unlike V4, these derive directly from UAttributeSet and each carries its own clamp logic — there is no shared abstract base:

That is 44 replicated FGameplayAttributeData fields, each using ReplicatedUsing = OnRep_* with REPNOTIFY_Always (V5_REPLICATE_ATTRIBUTE, V5AttributeSets.cpp:12). The clamps are domain-specific, not boilerplate. Combat PreAttributeChange (V5AttributeSets.cpp:76) floors Health/Stamina/Toxicity/Mana at zero, holds CritChance to [0,1], and keeps CritMultiplier/AttackSpeed at a 0.1 minimum so a debuff can never zero out a multiplier; PostGameplayEffectExecute (:94) re-clamps current-vs-max pairs after an instant effect. Honor uses three different clamp bands (V5AttributeSets.cpp:148): Bounty ≥ 0, the Paragon/Renegade/WitcherHumanity meters to [0,100], and the cop/triad/family reputations to a signed [-100,100]. Ship deliberately exempts ThrustForward/ThrustLateral from the positive clamp (:223) because thrust is a signed vector component. The V5.Gameplay.GE.ReplicationMetadata spec reflection-counts these and pins 14 / 9 / 11 / 10 (V5GameplayEffectTests.cpp:128-131) — a test that fails the moment an attribute loses its RepNotify.

The cell-gated ability base#

UV5_GameplayAbility_Base (V5GameplayAbilityBase.h:9) is Abstract, Blueprintable and adds exactly what a multi-cell roster needs. Its constructor sets InstancedPerActor instancing and LocalPredicted net execution (V5GameplayAbilityBase.cpp:43-45), so every cell inherits client-predicted, replicated activation. It carries a CellContext (:17) and a resolved CellTag; SetCellContext (.cpp:48) maps the enum to a native tag — EV5Cell::Urban → V5.Cell.Urban, MindPalace → V5.Layer.MindPalace (ResolveV5CellTag, .cpp:7) — and adds it to AbilityTags. The gate lives in CanActivateAbility (.cpp:58): after the Super check it returns true only when the cell tag is invalid, the source tags are empty, or SourceTags->HasTag(CellTag) (.cpp:70). This is a source-tag gate, subtly different from V4's ASC-active-cell check: a frontier verb activates only when the activation context is tagged frontier, which keeps a stray tag from firing a foreign cell's verb.

Twenty effects with real GAS configuration#

This is where V5 departs most from V4. Where V4 used one enum, a resolve table, and SetByCaller scaling, V5 ships twenty concrete UGameplayEffect subclasses (V5GameplayEffects.h:7-165) whose constructors configure real GAS modifiers via three helpers (V5GameplayEffects.cpp:7-40):

• Instant damage. Damage_Physical is an Instant additive -20 to Health (.cpp:43); Damage_Energy is -15 (.cpp:49).
• Periodic bleed. Damage_Bleed (.cpp:55) is a HasDuration 6 s effect with Period.Value = 1.0, bExecutePeriodicEffectOnApplication = true, and a -3 health tick — a genuine periodic GAS effect, not a flat hit.
• Stacking buffs. ConfigureStackingBuff (.cpp:29) builds a 30 s effect with AggregateByTarget, StackLimitCount = 3, RefreshOnSuccessfulApplication, ClearEntireStack expiry, and bDenyOverflowApplication = true (.cpp:21-25). Stamina regen adds +10 per stack (.cpp:65); twelve buffs share this shape.
• Oil coatings. ConfigureOilEffect (.cpp:35) is a 300 s, single-stack effect adding a crit-chance and an attack-speed modifier; the specter oil grant is (+0.12 crit, +0.10 attack) (.cpp:124), tuned per monster class.
• Persistent honor. Persistent_HonorMod (.cpp:144) is an Infinite effect adding +5 HonorScore and +2 ParagonScore at once.

The V5.Gameplay.GE.Stacking spec applies the stamina buff four times and asserts the active count caps at 3 and stamina lands at 80 — 50 + 3×10, the overflow denied (V5GameplayEffectTests.cpp:91-97). The V5.Gameplay.GE.Cancellation spec applies once (stamina 50 → 60), removes the handle, and asserts the restore to 50 (:110-117). These pin specific computed values that a hardcoded return could not satisfy.

A companion piece, UV5_StateMachine (V5StateMachine.h:32), is the narrative flag store, not a combat machine: SetFlag/GetFlag/ClearFlag over cell-namespaced FV5NarrativeFlagState rows carrying a revision and a Unix timestamp (:8), plus ExportSnapshot/ImportSnapshot for save round-trips, verified cross-cell at V5GameplayEffectTests.cpp:143-154.

The tag side backs all of this. V5/ue/Config/DefaultGameplayTags.ini declares 22 native tags under FastReplication=True — seven cell roots, the honor/bounty/paragon/renegade axis roots, and input/save roots. The UV5_GameplayTagRegistry game-instance subsystem (V5GameplayTagRegistry.h:10) requests 17 required tags on Initialize, and fails loud: missing tags land in MissingRequiredTags, bReady goes false, and each absence is logged as an error (V5GameplayTagRegistry.cpp:99-106) rather than silently tolerated.

The combat verb layer (V5Combat)#

V5Combat is the third-person gunplay that rides those GAS attributes, and it is real pure-function C++, mostly UBlueprintFunctionLibrary resolvers over the data types in V5CombatTypes.h (14 weapon classes, 7 cover states, 12 hit-reaction classes, 5 friendly-fire policies). The load-bearing math:

• Bullet penetration. ResolvePenetration (V5CombatRules.cpp:3) computes EffectiveResistance = max(Resistance·(Thickness/10) − ArmorPen, 0), blocks hard cover above 0.85, scales damage by clamp(1 − resistance), and counts a penetration only when the through-damage clears a 12% floor. The mechanics spec drives 40 cm concrete (bIsHardCover) and asserts the shot is stopped (V5CombatTests.cpp:191).
• Hit reactions. ResolveHitReaction (.cpp:17) is a tiered selector: headshot ≥ 75 → KO; armor-break → WallSlam; Hunter cell ≥ 55 → KOBleed (a cell-specific arm); ≥ 90 → SpinFall; ≥ 65 → Knockdown; ≥ 35 → HeavyStagger. The spec pins the 90 + headshot → KO outcome (V5CombatTests.cpp:193).
• Friendly fire. GetPolicyForCell (.cpp:46) gives each cell its own doctrine — Period Blocked, Hunter Allowed, Sci-Fi SquadOnly, Urban/Frontier HonorPenalty — and GetReputationPenalty charges 25 for a civilian, 10 for an ally, 35 for a squadmate (.cpp:79).

The feel systems are equally concrete. AdvanceADS (V5CombatAimDownSight.cpp:27) blends FOV toward the weapon's zoom with alpha = clamp(dt·12), decays recoil by 1 − dt·7, and recomputes an accuracy scalar from movement and residual recoil. TryAttachToCover (V5CombatCover.cpp:8) only sticks when the approach faces the cover — dot(approach, −normal) ≥ 0.2 and height ≥ 60 cm — and flags vaultability below 145 cm. UV5_Combat_StanceSubsystem is a real UWorldSubsystem (V5CombatStanceSubsystem.h:10) that gates ZeroG to the Sci-Fi cell and Horseback to Frontier (.cpp:5-18) and returns per-stance accuracy/recoil/ profile/movement scalars (prone drops profile to 0.32, .cpp:48). FireAtRange (V5CombatWeaponBase.cpp:11) ties it together: damage-at-range ×2 for headshots, through the penetration resolver, into the hit-reaction selector, with a recoil key pulled from the pattern catalog. That catalog is a real 197-weapon roster expanded from weapon_roster.json and validated per cell — Urban 65, Period 40, Frontier 22, Hunter 32, Sci-Fi 38 — with a tuning assertion that the 1899 revolver kicks more than twice as hard as the sci-fi rifle (V5CombatTests.cpp:79-97). The seam this layer does not cross is applying its computed damage back through a GAS Damage effect onto UV5_AttributeSet_Combat::Health; the resolvers return values, and the integration pawn (qualification 2) would land them.

Animation pipeline (V5Animation)#

V5Animation is a library of standalone algorithms plus a catalog validator. The motion-matching contract from the architecture — 0.5 s past trajectory, 1.0 s future intent — is enforced as data: ValidateAnimationCatalogJson (V5AnimationSystems.cpp:207) parses the 390k-line catalog and requires schema version 1, 30,000+ clips across five cells and three traversal modes, and 15 pose databases of ≥ 2000 clips each, rejecting any clip below the quality bars (poseCoverage ≥ 0.86, qualityScore ≥ 0.82, ≥ 9 trajectory samples; ParseClip, :157). EvaluateTraversalMatch (:334) scores a request as alignment·0.5 + speed·0.3 + window·0.2, accepts above 0.68, and returns a blend time lerped between 0.18 and 0.06 s; SpeedScoreForMode (:169) tunes the ideal speed per mode (run 4.8, walk 1.5, crouch 0.9 m/s). The pose-database quality spec averages every database and asserts mean quality ≥ 0.86 and coverage ≥ 0.9 (V5AnimationTests.cpp:110-133).

The IK and retarget side is real geometry. Seven solvers (V5AnimationSystems.cpp:373-455) each return an FV5AnimIKResult with a validity flag, effector transform, blend alpha, and chain tag: foot-to-ground, hand-to-ladder, hand-to-cover (target offset 0.08 m along the normal, valid within 0.45 m), hand-weapon-grip, head-look-at (yaw/pitch clamped to limits), and full-body mount keyed by Cockpit/Airlock/Horse. Three retargeters build MetaHuman → quadruped (horse, scale clamped 0.5–2.0), → wildlife, and → alien (Sci-Fi-only, :479). ResolveRootMotion (:490) accepts a delta only when the montage is a server-authoritative cinematic finisher and flags a client correction past 2 cm — the "root motion is server-authoritative" rule made testable (V5AnimationTests.cpp:80-82). SelectHitReactVariant (:500) is the Chooser stand-in: it derives a direction from the impact angle (back > 110°, left < −35°, right > 35°, else front) and a tier from damage (finisher ≥ 90, knockdown ≥ 60, heavy ≥ 30), composing a per-cell variant id like hitreact.frontier.finisher.back. This is the genuine selection logic an AnimBlueprint would call; today the call site is the test, and the engine Motion-Matching/IKRig/Chooser nodes that would consume these results are unlinked (qualification 4).

Input pipeline (V5Input)#

V5Input models Enhanced Input as a catalog and a planner rather than a live subsystem binding. ValidateInputContextsJson (V5InputSystems.cpp:179) loads input_context_catalog.json (417 lines) and requires schema version 1, 25+ mapping-context specs spanning all seven cells, all remappable; the spec confirms the count and that, e.g., IMC_SciFi_Pilot advertises HOTAS, IMC_Urban_Combat advertises Trackball, and IMC_Steampunk_GadgetWheel targets the Steampunk cell (V5InputTests.cpp:35-47). The stack planner is the core: BuildStackForCellAndMode (:315) selects the shared Menu/Remapping contexts always, the Dialogue context when the mode is Dialogue, and the cell-and-mode match otherwise, then sorts by priority then id (SortStack, :155). SwapIMCStack (:336) diffs the current and target stacks into AddedContexts/RemovedContexts and estimates SimulatedLatencyMs = 0.25·(added+removed) + 0.08·stackSize (:363), flagging whether it stays inside the request's budget. The latency spec swaps Urban-Walk → Sci-Fi-Pilot, asserts the swap stays under 8 ms, adds IMC_SciFi_Pilot, and keeps IMC_Shared_Menu (V5InputTests.cpp:117-131). That SimulatedLatencyMs is an estimate, not a measured cost, and no UEnhancedInputLocalPlayerSubsystem is touched.

The rest of the module is honest device support: a dialogue-wheel cursor that resolves a stick vector to a spoke via atan2 and floor(angle/360·spokes) (EvaluateCursor, :368; the spec maps straight-up to spoke 2 of 8), plus builders for adaptive-controller, HOTAS cockpit (5 axes / 4 buttons), racing-wheel (valid only for Urban/Frontier, :421), trackball, arcade-panel (6–12 buttons), iPad touch (Mind-Palace-primary drops the virtual stick), and per-platform VR profiles.

How cells share and specialize#

The four modules repeat one pattern — one shared mechanism, seven narrow specializations, all keyed on EV5Cell:

• Shared: the four attribute sets and their clamps, the cell-gated ability base and its predicted/replicated defaults, the twenty effects, the combat resolvers and stance subsystem, the motion-match scorer and IK/retarget solvers, the input catalog and stack planner, and the native tag table.
• Specialized per cell: which oil/sign/biotic effect a cell grants, which friendly-fire doctrine and stance gates apply (ZeroG ⇒ Sci-Fi, Horseback ⇒ Frontier), which motion-match database and per-cell hit-react table load, and which IMC stack a cell-and-mode switch assembles. Adding the Steampunk cell is a new enum arm plus catalog rows — no change to the shared spine.

How it connects#

These modules are the seam where everything else attaches. Where V5Gameplay, V5Combat, V5Animation, and V5Input sit in the full module graph, and the one-way cross-cell dependency rule that keeps them shareable, is laid out in ./topology-layout-module-split.md. The honor and reputation attributes (UV5_AttributeSet_Honor) and the friendly-fire penalties this layer computes feed the morality compass and NPC perception described in ./perception-crowd-and-morality.md. The reload montage paths, hit-react variant ids, dialogue-wheel cursor, and cinematic-finisher root motion this layer selects are realized by the presentation systems in ./audio-vfx-cinematics-ui.md. For these sections in prose and the full subsystem glossary, return to the hub: ../V5_ARCHITECTURE.md.

Related#

• Topology, Layout & Module Split — where these modules live and the cross-cell dependency rule
• Perception, Crowd & Morality — the honor attributes and friendly-fire penalties this layer produces
• Audio, VFX, Cinematics & UI — the montages, hit-react variants, and finisher root motion this layer selects
• The section hub: ../V5_ARCHITECTURE.md