Charged Basic Attack: Long-Press Left Click · CultivatingImmortality

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The long-press left click charge wind-up only affects the upper body — whether ground WASD running (lower-body locomotion in progress) or airborne legs executing a flight animation, the charge wind-up overlays well. After release, the release (fling) connects into the follow-through. Short taps retain the original basic attack combo, with no effect on feel.

— Core requirement

1. Final spec settled after three iterations

Version	User feedback	Revisions
V1 first version	—	Long press → One, release → Two → connects to Three; auto-release on timeout
V2 after PIE	Held down without releasing, so it auto-completed. It should keep charging the whole time	Long press without release → stays in One, plays to frame 75 → 65↔75 oscillation (charge breathing motion); force-release if cumulative exceeds 2 s
V3 tuning	Two is too slow	Two playback speed ×1.5 → ×1.5 again (final 2.25); acceptance satisfied

2. Short tap vs long press detection window

Left click is a single key, routed with a 0.25 s detection window:

Released within 0.25 s of pressing → Short tap → follows original basic attack combo (DoAttack → PlayMontage)
Released after more than 0.25 s of pressing → Long press → follows the charge chain (One → Two → Three)
Long press beyond 2 s still not released → Force release (charge auto-releases)

// CharacterBase.cpp · Left click input guard
void ACharacterBase::OnAttackPressedKey()
{
    if (bIsCharging) return;                    // Do not re-trigger during charge
    bWasChargingReleased = false;
    GetWorldTimerManager().SetTimer(
        ChargeKeyPressTimer, this,
        &ACharacterBase::OnChargeDetected, 0.25f, false);  // Detect after 0.25s
}

void ACharacterBase::OnAttackReleasedKey()
{
    if (!bWasChargingReleased) {
        // Released within 0.25s → short tap, follow basic attack
        GetWorldTimerManager().ClearTimer(ChargeKeyPressTimer);
        DoAttack(); return;
    }
    // Long press release → trigger charge release
    if (bIsCharging) { ReleaseCharge(); }
}

3. AnimGraph four-layer structure (the upper-body layering key)

The original ABP AB_角色蓝图 only contained 1 Slot(DefaultSlot); after adding layered Slots it was extended to four layers:

Locomotion(StateMachine)
  └─> Slot(DefaultSlot)                          ← Original full-body montage still goes here, unaffected
        ├─> SaveCachedPose(ChargeBasePose)
        │      ├─> UseCachedPose A ──> LayeredBoneBlend.BasePose
        │      └─> UseCachedPose B ──> Slot(UpperBody).Source
        └─> Slot(UpperBody).Pose ──> LayeredBoneBlend.BlendPoses_0
LayeredBoneBlend.Pose ──> LocalToComponentSpace ──> ModifyBone ──> TwoBoneIK×2 ──> AnimDynamics ──> KawaiiPhysics×5 ──> Root

Why use SaveCachedPose + UseCachedPose:

Inside DefaultSlot is the full-body Locomotion (walk / run / airborne leg animation); it is the "base".
SaveCachedPose saves a copy of the base Pose for LayeredBoneBlend.BasePose to use (keeping the lower body on the full-body Pose).
Slot(UpperBody) is the new layering entry; LayeredBoneBlend only blends the bones above the spine (Branch Filter filled with spine bone names), so the charge stacks only on the upper body while the legs continue walk/flight animations.

4. Three-segment animation and timing

Animation	Frame count	Duration	Playback speed	Loop
AM_CL_Attack_01_One (charge wind-up)	76	2.533 s	1.25×	Yes (65↔75 oscillation)
AM_CL_Attack_01_Two (fling)	30	1.0 s	2.25×	No
AM_CL_Attack_01_Three (follow-through)	45	1.5 s	1.0×	No

Key point: this animation sequence has no corresponding montage; it is played by calling PlayAnimation directly. When the charge wind-up One plays to frame 75 and the key is still held → the AnimBP Event BlueprintUpdateAnimation in the AnimBP drives a per-frame Tick, playing back and forth between progress 65↔75 (charge breathing effect).

5. Event-driven chain in the AnimBP

// AB_角色蓝图's AnimGraph Event BlueprintUpdateAnimation (per-frame Tick)
// Inputs: Player → IsCharging(bool), ChargeProgress(0-1 float)
// Actions:
//   if IsCharging=true → Set Slot(UpperBody) Pose = PlayAnimation(One)
//     play to frame 75 → Reverse → Forward oscillation between 65↔75
//   if IsCharging=false and bJustReleased=true → Set Slot(UpperBody) Pose = PlayAnimation(Two, then Three)
//   else → Slot(UpperBody) cleared → upper body returns to full-body Locomotion

6. Issues and fix list

Isolated InputKey node: in the Blueprint Attack graph, K2Node_InputKey_2 is an isolated node; the actual left click input is driven entirely by C++ (bBindLegacyAttackKey → BindKey(LeftMouseButton, IE_Pressed)). Do not modify the Blueprint isolated node.
LayeredBoneBlend branch filter bone names: the Branch Filter must be filled with spine bone names (spine_01 / spine_02 / spine_03); if not filled, the entire body is covered by the charge animation.
C++ and AnimBP data sync: the two variables IsCharging / ChargeProgress in the Player Blueprint are written by C++ and read by the AnimBP. AnimBP Event BlueprintUpdateAnimation reads every frame and should not be read only once in Event Blueprint Initialize.
Charge timing independent of the montage system: because the charge animation is not a montage (no Slot Montage), the timing logic is managed separately on the C++ side TimeManager; the AnimBP only drives LayeredBoneBlend according to C++ state.
Dash during charge must be interrupted first: the dash guard if (bIsCharging) { StopCharge(); }; otherwise two AnimGraph sources drive the same Slot simultaneously, causing animation tearing.