2nd/10_Wiki/Topics/Frontend/Guilty-Gear-Xrd-Rendering-Pipeline.md

id, title, category, status, canonical_id, aliases, duplicate_of, source_trust_level, confidence_score, verification_status, tags, raw_sources, last_reinforced, github_commit, tech_stack

id	title	category	status	canonical_id	aliases	duplicate_of	source_trust_level	confidence_score	verification_status	tags	raw_sources	last_reinforced	github_commit	tech_stack
wiki-2026-0508-guilty-gear-xrd-rendering-pipeli	Guilty Gear Xrd Rendering Pipeline	10_Wiki/Topics	verified	self	Xrd Toon Shading Arc System Works Anime Render Guilty Gear Cel Shading	none	A	0.9	applied	graphics cel-shading npr anime arc-system-works		2026-05-10	pending	language framework hlsl unreal-engine

Guilty Gear Xrd Rendering Pipeline

매 한 줄

"매 3D model 을 매 2D anime 처럼 보이게 매 render — 매 artist control 이 매 algorithm 보다 매 우선.". Arc System Works (Junya C. Motomura, GDC 2014) 의 매 Xrd 파이프라인은 매 NPR (non-photorealistic rendering) 의 매 landmark. 매 hand-painted normal + custom shadow + ink line + post-processing 의 매 stack.

매 핵심

매 Pipeline stage

1. Modeling: 매 low-poly model + 매 hand-tuned vertex normal.
2. Base color shading: 매 ramp texture (1D LUT) — 매 toon step.
3. Custom shadow direction: 매 light vector 무시 + 매 artist 가 매 manual paint.
4. Outline (ink line): 매 inverted hull / 매 post-process edge.
5. Specular & rim: 매 hand-placed highlight texture.
6. Post-processing: 매 chromatic aberration, 매 bloom, 매 color grading.

매 Vertex normal trick

• 매 face 의 매 normal 을 매 sphere 로 매 매뉴얼 average — 매 2D 에서 매 깔끔한 shadow shape.
• 매 hair 는 매 normal 을 매 head 의 매 center 로 매 향하게 — 매 anisotropic specular 의 매 illusion.

매 Ramp texture

• 1D texture, 매 N·L → matrix lookup. 매 step 2-3 단계 — 매 hard edge.
• 매 character 별 매 다른 ramp — 매 다른 mood.

매 Outline

• Backface inverted hull: 매 model 을 매 normal 방향 outward extrude + cull front. 매 cheap, 매 thickness 균일.
• Vertex color mask: 매 detail line 의 매 thickness 제어.

매 응용

1. Anime fighting game (Dragon Ball FighterZ, Granblue Versus 도 매 변형).
2. Mobile RPG (Genshin Impact 의 매 cel).
3. VTuber rendering.

💻 패턴

Toon shader (HLSL)

float NdotL = saturate(dot(normalize(worldNormal), lightDir));
float ramp  = tex2D(_RampTex, float2(NdotL, 0.5)).r;
float3 base = tex2D(_MainTex, uv).rgb;
float3 col  = base * lerp(_ShadowColor, 1.0, ramp);
return float4(col, 1);

Inverted hull outline

// Vertex pass — render with cull = Front
float3 normalWS = TransformObjectToWorldNormal(IN.normal);
float3 posWS    = TransformObjectToWorld(IN.positionOS) + normalWS * _OutlineWidth;
OUT.positionCS  = TransformWorldToHClip(posWS);
OUT.color       = _OutlineColor;

Custom shadow direction (face)

// Replace light dir with artist-specified vector for face
float3 fixedLight = mul((float3x3)unity_ObjectToWorld, _FaceLightDir);
float NdotL = dot(worldNormal, normalize(fixedLight));

Hair tangent trick

// Hair anisotropic — tangent points along hair flow
float3 H = normalize(viewDir + lightDir);
float TdotH = dot(hairTangent, H);
float spec  = pow(1.0 - TdotH * TdotH, _HairGloss);

Edge detect post (Sobel on depth+normal)

float3 nC = SampleNormal(uv);
float dC  = SampleDepth(uv);
float edge = 0;
[unroll] for (int i = 0; i < 4; ++i) {
  float3 nS = SampleNormal(uv + offset[i] * _TexelSize);
  float dS  = SampleDepth(uv + offset[i] * _TexelSize);
  edge += saturate(1.0 - dot(nC, nS)) + abs(dC - dS) * _DepthWeight;
}
return lerp(sceneColor, _EdgeColor, saturate(edge - _Threshold));

Ramp texture authoring (Python)

import numpy as np
from PIL import Image
ramp = np.zeros((1, 256, 3), dtype=np.uint8)
ramp[0, :64]   = (60, 50, 80)     # deep shadow
ramp[0, 64:160] = (140, 130, 150) # mid
ramp[0, 160:]   = (250, 245, 240) # lit
Image.fromarray(ramp).save('toon_ramp.png')

Specular hand-placed mask

// Per-pixel mask painted by artist — multiplies spec
float specMask = tex2D(_SpecMaskTex, uv).r;
float3 spec    = pow(saturate(dot(N, H)), _Power) * specMask * _SpecColor;

매 결정 기준

효과	Approach
매 hard cel shadow	Ramp 1D texture + step
매 face shadow control	Custom light vector
매 cheap outline	Inverted hull (backface)
매 detail outline	Post-process Sobel on N+depth
매 anime hair	Tangent-based aniso + ramp
매 emotional rim	Hand-placed highlight mask

기본값: ramp + inverted hull + face light override. 매 modern (Unreal/Unity) 모두 매 stable.

🔗 Graph

• 부모: Computer Graphics

🤖 LLM 활용

언제: 매 anime / cel-shading 재현, 매 NPR 학습, 매 outline / shadow 의 매 trick 분석. 언제 X: 매 photorealistic — 매 PBR 파이프라인.

❌ 안티패턴

• Auto-generated normal: 매 anime look 의 매 핵심 — 매 hand-tune 필수.
• Light dir 만 의존: 매 face 매 dirty shadow.
• Outline 두께 globally same: 매 detail loss — 매 vertex color mask.
• Bloom 만 의존한 mood: 매 ramp / grading 이 매 base.

🧪 검증 / 중복

• Verified (Junya C. Motomura, "Guilty Gear Xrd's Art Style", GDC 2014).
• 신뢰도 A.

🕓 Changelog

날짜	변경
2026-05-08	Phase 1
2026-05-10	Manual cleanup — 매 Xrd pipeline + HLSL 패턴