godot-genre-shooter-fps

What this skill does

# Genre: Shooter (FPS/TPS)

Gunplay feel, responsive combat, and competitive balance define shooters.

## NEVER Do (Expert Anti-Patterns)

### Gunplay & Hit Registration
- NEVER use `_process()` for hit detection; strictly use `_physics_process()` to maintain frame-rate independent accuracy.
- NEVER apply recoil to the physical weapon model; strictly apply it to **Camera Rotation (kick)** and **Weapon Bloom (spread)**.
- NEVER trust the client for hit registration in multiplayer; strictly use **Server-Authoritative** validation with lag compensation.
- NEVER synchronize every bullet over the network; strictly use **Client-Side Prediction** and send only initial "Fire" events.
- NEVER use `Area3D` or `move_and_collide()` for high-speed ballistics; strictly use `PhysicsDirectSpaceState3D.intersect_ray()` for 100x better performance.
- NEVER forget to exclude the player's own RID from hitscan raycasts; otherwise, shots will collide instantly with the barrel.
- NEVER use exact floating-point equality (==) for weapon cooldowns or timers; strictly use `is_equal_approx()`.

### Performance & Polish
- NEVER use a single `AudioStreamPlayer` for gunfire; strictly use **Layered Audio** (Mechanical + Shot + Reverb Tail).
- NEVER instantiate and `free()` hundreds of projectile nodes; strictly use **Object Pooling** or the `RenderingServer`.
- NEVER use `Sprite3D` or `QuadMesh` for bullet impacts; strictly use the **Decal** node for surface-conforming texture projection.
- NEVER leave decals in the scene indefinitely; strictly implement a fade-out and cleanup cycle.
- NEVER use `Transform3D.looking_at()` for forward shooting vectors; strictly extract the direction from `-transform.basis.z`.
- NEVER multiply velocity by `delta` before `move_and_slide()`; the method internalizes the timestep automatically.

### Input & Architecture
- NEVER poll mouse motion inside `_physics_process()`; strictly use `_input()` for zero-latency camera look.
- NEVER accumulate mouse rotation directly onto a `Transform3D`; strictly store **Yaw/Pitch variables** to avoid gimbal lock.
- NEVER hardcode weapon statistics (Damage, Recoil) inside logic; strictly use **Resource-based WeaponData** for balancing.
- NEVER tightly couple damage logic to specific classes; strictly use **Duck-Typing** (`has_method("take_damage")`) for environment interactivity.
- NEVER use standard Strings for high-frequency state identifiers; strictly use `StringName` (e.g., `&"reloading"`).
- NEVER use the `!` (NOT) operator in AnimationTree expressions; strictly use `is_firing == false`.
- NEVER connect weapon signals via string-based calls; strictly use **Signal-Object syntax** (`fired.connect`).

---

## 🛠 Expert Components (scripts/)

### Original Expert Patterns
- [advanced_weapon_controller.gd](scripts/advanced_weapon_controller.gd) - Professional-grade weapon system with deterministic recoil, bloom, and dual hitscan/projectile modes.

### Modular Components
- [fps_camera_look.gd](scripts/fps_camera_look.gd) - Asynchronous mouse look for zero-latency aiming using raw input.
- [hitscan_weapon_query.gd](scripts/hitscan_weapon_query.gd) - Nodeless physics raycast pattern for instant hit registration.
- [fps_movement_logic.gd](scripts/fps_movement_logic.gd) - Physics-based movement with acceleration, friction, and gravity scaling.
- [weapon_bobbing_system.gd](scripts/weapon_bobbing_system.gd) - Procedural bobbing and sway using sine-wave oscillation.
- [bullet_decal_spawner.gd](scripts/bullet_decal_spawner.gd) - Dynamic surface decal projection for impact effects.
- [weapon_spread_calc.gd](scripts/weapon_spread_calc.gd) - Gaussian/Normal distribution logic for bullet clustering.
- [server_projectile_instance.gd](scripts/server_projectile_instance.gd) - High-volume visual bullets using RenderingServer RIDs.
- [weapon_state_machine.gd](scripts/weapon_state_machine.gd) - Optimized state transitions for fire, reload, and idle.
- [player_anim_bridge.gd](scripts/player_anim_bridge.gd) - Local velocity bridge for syncing movement with AnimationTree.
- [frame_perfect_input.gd](scripts/frame_perfect_input.gd) - Buffered semi-automatic input handling to prevent dropped shots.

---

## Core Loop

`Engage → Aim → Fire → Kill Confirm → Acquire Next`

---

## Weapon System Architecture

```gdscript
class_name Weapon
extends Node3D

@export_group("Stats")
@export var damage: int = 20
@export var fire_rate: float = 0.1  # Seconds between shots
@export var magazine_size: int = 30
@export var reload_time: float = 2.0
@export var range: float = 100.0

@export_group("Recoil")
@export var base_recoil: Vector2 = Vector2(0.5, 2.0)  # X, Y degrees
@export var recoil_recovery_speed: float = 5.0
@export var max_spread: float = 5.0

@export_group("Type")
@export var is_hitscan: bool = true
@export var projectile_scene: PackedScene

var current_ammo: int
var can_fire: bool = true
var current_recoil: Vector2 = Vector2.ZERO
var current_spread: float = 0.0

signal fired
signal reloaded
signal ammo_changed(current: int, max: int)
```

---

## Hitscan vs Projectile

### Hitscan (Instant Hit)

```gdscript
func fire_hitscan() -> void:
    if not can_fire or current_ammo <= 0:
        return
    
    current_ammo -= 1
    ammo_changed.emit(current_ammo, magazine_size)
    
    var camera := get_viewport().get_camera_3d()
    var ray_origin := camera.global_position
    var ray_direction := -camera.global_basis.z
    
    # Apply spread
    ray_direction = apply_spread(ray_direction)
    
    var space := get_world_3d().direct_space_state
    var query := PhysicsRayQueryParameters3D.create(
        ray_origin,
        ray_origin + ray_direction * range
    )
    query.collision_mask = collision_mask
    
    var result := space.intersect_ray(query)
    if result:
        var hit_point: Vector3 = result.position
        var hit_normal: Vector3 = result.normal
        var hit_object: Object = result.collider
        
        spawn_impact_effect(hit_point, hit_normal)
        
        if hit_object.has_method("take_damage"):
            var hit_zone := determine_hit_zone(result)
            var final_damage := calculate_damage(damage, hit_zone)
            hit_object.take_damage(final_damage, hit_zone)
    
    apply_recoil()
    start_fire_cooldown()
    fired.emit()

func determine_hit_zone(result: Dictionary) -> String:
    # Use collision shape name or bone detection for hitboxes
    if "headshot" in result.collider.name.to_lower():
        return "head"
    elif "chest" in result.collider.name.to_lower():
        return "chest"
    return "body"

func calculate_damage(base: int, zone: String) -> int:
    match zone:
        "head": return int(base * 2.5)
        "chest": return int(base * 1.0)
        _: return int(base * 0.8)
```

### Projectile (Physical Bullet)

```gdscript
class_name Projectile
extends CharacterBody3D

@export var speed := 100.0
@export var damage := 20
@export var gravity_affected := true
@export var lifetime := 5.0

var direction: Vector3
var shooter: Node3D

func _ready() -> void:
    await get_tree().create_timer(lifetime).timeout
    queue_free()

func _physics_process(delta: float) -> void:
    if gravity_affected:
        velocity.y -= 9.8 * delta
    
    velocity = direction * speed
    var collision := move_and_collide(velocity * delta)
    
    if collision:
        var collider := collision.get_collider()
        if collider != shooter and collider.has_method("take_damage"):
            collider.take_damage(damage)
        spawn_impact(collision.get_position(), collision.get_normal())
        queue_free()
```

---

## Recoil System

Three types of recoil working together:

```gdscript
class_name RecoilSystem
extends Node

var visual_recoil: Vector2 = Vector2.ZERO    # Camera kick
var pattern_offset: Vector2 = Vector2.ZERO   # Deterministic pattern
var spread_bloom: float = 0.0                # Accuracy loss

@export var recoil_pattern: Array[Vector2]   # Predefined spray pattern
var pattern_index: int = 0

fun