2nd/10_Wiki/Topics/Architecture/Stat-Injection-and-Visual-Renderer-Pipeline.md

---
id: wiki-2026-0508-stat-injection-and-visual-render
title: Stat Injection and Visual Renderer Pipeline
category: 10_Wiki/Topics
status: verified
canonical_id: self
aliases: [Stat Injection Pipeline, Visual Renderer Pipeline]
duplicate_of: none
source_trust_level: B
confidence_score: 0.8
verification_status: applied
tags: [game-engine, ecs, rendering-pipeline, data-flow]
raw_sources: []
last_reinforced: 2026-05-10
github_commit: pending
tech_stack:
  language: rust
  framework: bevy
---

# Stat Injection and Visual Renderer Pipeline

## 매 한 줄
> **"매 simulation stats (HP, mana, status) → 매 visual layer (sprites, VFX, UI) 의 one-way injection pipeline"**. 매 game engine 의 ECS pattern + 매 render system. 매 simulation tick 의 authoritative state → 매 frame-rate-independent rendering. 2026 매 Bevy ECS, Unity DOTS, Unreal MASS 가 매 reference.

## 매 핵심

### 매 데이터 흐름
1. **Simulation tick** (fixed 60 Hz): 매 stats mutation (Damage, Heal, StatusEffect).
2. **Stat aggregation**: 매 base + buffs + equipment modifiers.
3. **Injection layer**: 매 simulation stats → 매 visual components (HealthBar, SpriteTint, ParticleEmitter).
4. **Render pipeline**: 매 cull → batch → draw call → GPU.
5. **Frame interpolation**: 매 sim tick rate 와 매 render rate 의 mismatch 의 smooth.

### 매 layers
- **Authoritative**: simulation Components (Health, Mana, Position).
- **Derived/Display**: Visual Components (DisplayHealth, FlashTimer, FloatingText).
- **Renderer**: Sprite, Mesh, Material, Shader.
- **Pipeline stages**: Update → Late Update → PostUpdate → Render.

### 매 응용
1. RPG combat — damage number 의 popup, sprite flash on hit.
2. RTS — health bar, status icon, fog-of-war overlay.
3. Action game — hit-stop, screen shake, VFX 의 trigger.

## 💻 패턴

### Bevy ECS (Rust 1.83) — stat → visual injection
```rust
use bevy::prelude::*;

#[derive(Component)] struct Health { current: f32, max: f32 }
#[derive(Component)] struct HealthBar; // visual marker
#[derive(Component)] struct DamageFlash { timer: Timer }

fn inject_health_to_bar(
    actors: Query<&Health, Changed<Health>>,
    mut bars: Query<(&Parent, &mut Sprite), With<HealthBar>>,
) {
    for (parent, mut sprite) in bars.iter_mut() {
        if let Ok(h) = actors.get(parent.get()) {
            let ratio = h.current / h.max;
            sprite.custom_size = Some(Vec2::new(64.0 * ratio, 6.0));
            sprite.color = Color::rgb(1.0 - ratio, ratio, 0.0);
        }
    }
}
```

### Damage event → flash injection
```rust
#[derive(Event)] struct DamageEvent { target: Entity, amount: f32 }

fn on_damage(
    mut events: EventReader<DamageEvent>,
    mut commands: Commands,
    mut healths: Query<&mut Health>,
) {
    for ev in events.read() {
        if let Ok(mut h) = healths.get_mut(ev.target) {
            h.current -= ev.amount;
            commands.entity(ev.target).insert(DamageFlash {
                timer: Timer::from_seconds(0.15, TimerMode::Once),
            });
        }
    }
}

fn tick_flash(
    time: Res<Time>,
    mut q: Query<(Entity, &mut DamageFlash, &mut Sprite)>,
    mut commands: Commands,
) {
    for (e, mut f, mut s) in q.iter_mut() {
        f.timer.tick(time.delta());
        s.color = if f.timer.finished() { Color::WHITE } else { Color::RED };
        if f.timer.finished() { commands.entity(e).remove::<DamageFlash>(); }
    }
}
```

### Frame interpolation (fixed sim, variable render)
```rust
#[derive(Component)] struct Transform2D { pos: Vec2 }
#[derive(Component)] struct PrevPos(Vec2);

fn interpolate_render(
    fixed: Res<FixedTime>,
    q: Query<(&Transform2D, &PrevPos, &mut Transform)>,
) {
    let alpha = fixed.accumulated().as_secs_f32() / fixed.timestep().as_secs_f32();
    for (cur, prev, mut t) in q.iter_mut() {
        let p = prev.0.lerp(cur.pos, alpha);
        t.translation = p.extend(t.translation.z);
    }
}
```

### Render pipeline stages (Bevy schedule)
```rust
app.add_systems(FixedUpdate, (apply_damage, regen_mana))
   .add_systems(Update, (inject_health_to_bar, tick_flash))
   .add_systems(PostUpdate, (cull_offscreen, batch_sprites));
```

### Floating damage text
```rust
fn spawn_damage_text(mut commands: Commands, mut events: EventReader<DamageEvent>,
                     transforms: Query<&Transform>) {
    for ev in events.read() {
        let tf = transforms.get(ev.target).unwrap();
        commands.spawn((
            Text2dBundle { text: Text::from_section(format!("{}", ev.amount as i32),
                TextStyle { font_size: 24.0, color: Color::YELLOW, ..default() }),
                transform: *tf, ..default() },
            FloatingText { lifetime: Timer::from_seconds(1.0, TimerMode::Once), velocity: Vec2::Y * 50.0 },
        ));
    }
}
```

### Modifier aggregation (base + buffs + equipment)
```rust
fn aggregate_attack(
    mut q: Query<(&BaseStats, &Buffs, &Equipment, &mut DerivedAttack)>,
) {
    for (base, buffs, eq, mut atk) in q.iter_mut() {
        let mut v = base.attack;
        v += eq.iter().map(|i| i.attack_bonus).sum::<f32>();
        v *= 1.0 + buffs.iter().map(|b| b.attack_mult).sum::<f32>();
        atk.0 = v;
    }
}
```

## 매 결정 기준
| 상황 | Approach |
|---|---|
| Modern data-oriented engine | Bevy ECS / Unity DOTS / Unreal MASS |
| OOP legacy engine | Component pattern + observer for stat→visual |
| Multiplayer authoritative server | Server simulation, client interpolation |
| Animation-heavy | Skeletal animation system separate from stats |

**기본값**: ECS — sim Components → 매 system 의 derive Visual Components → renderer 의 read-only.

## 🔗 Graph
- 부모: [[Entity Component System]]
- Adjacent: [[Bevy]] · [[Fixed Timestep]]

## 🤖 LLM 활용
**언제**: 매 game development, 매 simulation/render decoupling, 매 ECS pipeline 의 design.
**언제 X**: 매 일반 web/backend, 매 simple tool — over-engineering.

## ❌ 안티패턴
- **Render reads sim mid-tick**: 매 tearing — 매 PostUpdate 의 inject 의 사용.
- **Visual mutates simulation**: 매 one-way 의 violation — 매 determinism 의 lost (multiplayer fatal).
- **Damage 의 main thread blocking VFX**: 매 frame drop. 매 event-driven, async.
- **Per-frame allocation**: 매 GC stutter — 매 object pool, 매 ECS의 contiguous storage.

## 🧪 검증 / 중복
- Verified (Bevy 0.14 docs 2025; Unity DOTS docs; *Game Engine Architecture* Gregory 3rd ed).
- 신뢰도 B (synthesis from multiple engine practices).

## 🕓 Changelog
| 날짜 | 변경 |
|---|---|
| 2026-05-08 | Phase 1 |
| 2026-05-10 | Manual cleanup — full ECS injection pipeline with Bevy patterns |