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Ray-MMD "ReForge" Documentation

Welcome to the official documentation for Ray-MMD ReForge, the modern physical-based rendering (PBR) engine for MikuMikuDance (MMD).

Ray-MMD ReForge modernizes the classic Ray-MMD architecture with state-of-the-art rendering technology inspired by Unreal Engine 5, Blender 4.0, and modern computer graphics research while maintaining 100% backward compatibility with the existing Ray-MMD 1.5.2 material ecosystem.

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Key Highlights

• Modular PMX Controller Suite (LightingController.pmx, CameraController.pmx, FogController.pmx, etc.): The monolithic ray_controller.pmx has been completely decommissioned in favor of a modern suite of specialized, lightweight controllers with zero bloat and universal fallback bindings.
• Physical Volumetric Fog & Atmospheric Godrays (FogController.pmx): Comprehensive unified atmospheric engine featuring analytical dual-layer exponential height fog and physically raymarched volumetric godrays coupled to solar zenith angle and CSM shadow cascades, with real-time wind drift, mist turbulence noise, and 42 dedicated controller morphs.
• Google Filament PBR & Shading Algorithms: Belcour & Barla (2017) physical thin-film spectral iridescence for clear coat, Kulla-Conty multi-bounce specular energy conservation for IBL, Oat & Sander / Jimenez analytical spherical caps intersection for Specular AO, physical $(1 - F_c)$ energy conservation under clear coat, colored penumbra (Filament fake SSS) for soft organic transitions, and Jimenez specular multi-bounce AO for colored metals.
• 4-Wavelength Spectral Dispersion & Beer-Lambert Volume Absorption: Physically based optical depth attenuation ($T = e^{-\sigma_{\text{abs}} \cdot d}$) and 4-spectral wavelength dispersion ($K_0..K_3$ at 486.1, 546.1, 589.3, 656.3 nm) with temporal jitter for glass, gems, and deep water.
• Next-Gen PCSS & Screen-Space Contact Cone Tracing (SSCT): True physically based contact-hardening Percentage-Closer Soft Shadows (SUN_SHADOW_PCSS_ENABLE) driven by physical solar radius, Castaño (2013) 4-tap PCF 3x3 filtering for fast cascades, paired with SSCT cone tracing for razor-sharp contact grounding with expanding soft penumbra.
• Gran Turismo 7 (GT7) & AgX Golden Tonemappers: Polyphony Digital's SIGGRAPH 2025 physically based tone curve calibrated to 250 nits paper white, Troy Sobotka's AgX Golden Look, and Gjøl (2016) triangular TPDF RGB dithering eliminating 8-bit banding without colored artifacts.
• Clean 10-Domain Modular Shader Architecture: Reorganized 54 loose shader files in Shader/ into 10 structured, domain-isolated packages (Core/, Lighting/, Shadows/, Occlusion/, GI/, SSR/, Subsurface/, PostProcess/, AntiAliasing/, textures/) with zero broken includes.
• SSPT / RTGI & SSGI 3.0 (Screen-Space Path Traced Global Illumination): Next-generation screen-space path tracing engine (GI_ENABLE 3, default) inspired by Marty McFly's qUINT RTGI, alongside UE5 Lumen-style SSGI 3.0. Features golden angle spiral sampling, progressive quadratic ray stepping, depth thickness gating, secondary bounce feedback, escaped-ray sky radiance, skin albedo-driven multi-bounce, dielectric glass transmission, deferred post-GI ambient occlusion, and direct shadow retention.
• Anti-Aliasing Suite & SMAA Ultra+ (AA_QUALITY 5, Default): Native 1x Ultra SMAA with G-Buffer linear depth predication, dual-axis bilinear sample weights, and subpixel micro-feature reconstruction, plus G-DLAA and 5-tap Catmull-Rom bicubic TAA.
• Studio Color Grading Engine & Dedicated Controller (ColorGradingController.pmx): Pre-tonemap linear HDR 3-way split-toning (Lift/Gamma/Gain for Shadows, Midtones, Highlights) with Naka-Rushton perceptual luma partitioning, 2D white balance (Temperature + Tint), smart Vibrance, 3D Rodrigues Hue rotation, and cinematic presets (Teal & Orange, Bleach Bypass, Cross Process, Monochrome).
• Top-Down Sky Visibility (Snowdrop Engine): Directional heightfield horizon search and cone-tracing macro ambient occlusion preventing outdoor skylight / ambient IBL leakage under canopies, roofs, bridges, and doorways with dedicated SkyVisibilityController.pmx.
• Vectorized Screen-Space Reflections (SIMD SSRT) & Stabilized Glass Refraction: High-performance screen-space ray tracing using vectorized linear SIMD marching with 4-sample texture batching, dynamic slope-scaled tolerance, direct hit-tap binding, 4-tab per-material reflection masks (SSRMap, SSRReflectMap, SSRSelfMap, SSRBlurMap), and multi-mode diagnostic controller (SSRDebugController.pmx). Paired with Mayer et al. (2026) Newton's method 3D glass refraction.
• Unified UE Skin SSS Toolchain & Texture-Space Diffusion (SSSS_TEXSPACE 1): WrappedDiffuse, AO-scaled BackScatter, view-dependent InScatter, Beer-Lambert transmission with HSV hue shift, Henyey-Greenstein backlit glow, and camera-invariant model UV-space irradiance convolution.
• Band-Limited Hashed Alpha Hair Cutout & _realistic Presets: Dave Hoskins polynomial hash without sine, band-limited boundary stippling with 100% solid grain-free interior, plus 40 dedicated *_realistic.fx shaders across the hair library.
• ClearCoat Snell Refraction & Two-Sided Subsurface Transmission: Physical Snell angular deflection with Beer-Lambert absorption for ClearCoat, and Steve McAuley (2011) energy-conserving two-sided wrapped transmission for foliage, paper, and thin geometry.
• Real-Time Directional Water Caustics: Physically inspired underwater wave curvature flux concentration with dispersion and dedicated CausticsController.pmx.
• Atmospheric Volumetric Clouds 2.0: SA_DirectX 3.0 cumulus formations with Frostbite/Nubis multi-scattering lighting, adaptive empty space skipping, and planetary Earth curvature.
• Energy-Preserving Oren-Nayar (EON) BRDF: Exact Portsmouth et al. (JCGT 2025) diffuse BRDF preserving bounce energy across high roughness angles.
• Procedural Foliage Wind Engine: Zero-rigging vertex wind animation for trees, grass, vines, and palms — shadows, reflections, and GI bounce animate in sync.
• Eye Suite & Procedural Micro-Glitter: Refractive cornea dome with iris parallax mapping, analytical eye iris caustics, and multi-layer stochastic glitter presets.
• Panavision Flares & 35mm Film Halation: Cinematic cyan-blue streak profile and CineStill 800T multi-scale red-amber film emulsion bleed.

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Documentation Index

Section	Description
Quick Start Guide	Step-by-step setup in MikuMikuDance (Ray.x, Controller, Skybox, Materials).
Configuration Reference	Detailed parameter reference for all features in ray.conf.
Global Illumination (SSPT & SSGI 3.0)	Operating modes (RTGI / SSPT, Indirect, Accent), path tracing, 3D hemisphere raymarching, quality presets, and tuning knobs.
Materials & PBR Shading	Guide to Skin, Hair, Eye, Glass, Metal, Cloth, ClearCoat, and Subsurface materials.
ReForge Material Editor	Node-based PBR material authoring tool, PMX model studio, and batch converter.
Toon Shading	CEL / tone-based shading models, the Materials/Toon library, look grading knobs, and recommended config.
Lighting & Shadows	Directional Sun, Point, Spot, Tube, Sphere lights, PCSS, Contact Shadows, and Snowdrop Sky Visibility.
Color Grading & Tonemapping	Studio Color Grading Engine (ColorGradingController.pmx), AgX, ACES, Filmic operators, Bloom, Lens Flares, and Fog.
Troubleshooting & FAQ	Solutions for black screens, render limits, performance, and common setup errors.
Architecture & Changelog	Version history and technical architecture breakdown.