Post Effects Overview后处理全景

Pipeline Order — How Effects Chain管线顺序 — 效果如何串联

NeoX's post-processing pipeline is a fixed sequence of render passes. The final_composite.hlsl (1412+ lines) consolidates the final assembly stage — FXAA, bloom, DOF, tone mapping, color grading, sharpening, vignette, and grain all execute in a single pass to minimize bandwidth:

NeoX 的后处理管线是固定的渲染 Pass 序列。final_composite.hlsl（1412+ 行）整合了最终合成阶段——FXAA、泛光、景深、色调映射、调色、锐化、暗角和胶片颗粒均在单次 Pass 中执行以最小化带宽：

ACES Tone Mapping — Full Reference PipelineACES 色调映射 — 完整参考管线

aces.hlsl (1109 lines) implements the complete Academy Color Encoding System reference pipeline. This is the same standard used in film production. Three main stages:

aces.hlsl（1109 行）实现了完整的学院色彩编码系统参考管线。这与电影制作中使用的标准相同。三个主要阶段：

// ACES full path (aces.hlsl)
float3 ACESFilm(float3 scene_linear) {
  float3 aces = mul(sRGB_to_AP0, scene_linear);  // scene-linear sRGB → AP0
  float3 oces = RRT(aces);                        // RRT: AP0 → OCES
  float3 out  = ODT_sRGB_D65(oces);              // ODT: OCES → display sRGB
  return out;
}

// Glow module (applied before RRT desaturation)
// yc = rgb_2_yc(rgb)  -- luminance proxy with chroma boost
// glow_fwd: linear ramp from full gain at 2/3*mid to zero at 2*mid
float glow_fwd(float yc, float glowGain, float glowMid) {
  if (yc <= 2/3 * glowMid)       return glowGain;
  else if (yc >= 2 * glowMid)    return 0;
  else return glowGain * (2*glowMid - yc) / (4/3 * glowMid);
}

Temporal Anti-Aliasing (TAA)时间抗锯齿（TAA）

temporal_aa.hlsl (624 lines) implements 4 quality tiers. The highest quality mode uses Catmull-Rom history resampling and variance-based clamping with anti-flicker support:

temporal_aa.hlsl（624 行）实现 4 个质量等级。最高质量模式使用 Catmull-Rom 历史重采样和带防闪烁支持的方差截断：

// Key TAA steps (HIGH quality path)
// 1. Velocity dilation: find closest-depth neighbor in 5-cross
// 2. YCoCg color space + tone-mapped weighting (color/(luma+4))
// 3. Gaussian-weighted 3x3 current frame filter
// 4. Catmull-Rom bicubic history resampling (5-tap)
// 5. Variance clamping: sigma = stdDev * (1.5 + localizedAntiFlicker)
// 6. ClipHistory to neighbor AABB
// 7. Adaptive blend: base 0.12 modulated by speed + depth mismatch

// Anti-flicker: increase clamping box when neighbor variance is high
float localizedAntiFlicker = saturate(length(neighborhoodVariance) * antiFlickerStrength);
sigmaScale = 1.5 + localizedAntiFlicker;

Bloom — Threshold + Separable Gaussian泛光 — 阈值 + 可分离高斯

Bloom uses a 4-pass pyramid: threshold extraction → 3-4 levels of 5-tap Gaussian blur (separate H + V passes) → composite. The threshold uses a soft knee to avoid hard cutoffs:

泛光使用 4-Pass 金字塔：阈值提取→3-4 级 5 点高斯模糊（H+V 分离 Pass）→合成。阈值使用软膝盖避免硬截断：

// bloom_bright.hlsl — soft threshold
float TotalLuminance = Luminance(LinearColor) * ExposureScale;
float BloomAmount = saturate((TotalLuminance - Threshold) / 2.0);
return BloomAmount * LinearColor;

// bloom_blur_h.hlsl — 5-tap Gaussian kernel
// weights: {0.38774, 0.24477, 0.24477, 0.06136, 0.06136}
// offsets: {0, +1, -1, +2, -2} * BloomWidth / RT_size

Depth of Field — Standard + Bokeh SVD景深 — 标准 + 散景 SVD

Two DOF systems are available. Standard DOF is a simple separable Gaussian blur weighted by Circle of Confusion. Bokeh DOF uses SVD (singular value decomposition) approximation to simulate shaped aperture bokeh without expensive full 2D convolution:

提供两个景深系统。标准景深是按弥散圆加权的简单可分离高斯模糊。散景景深使用 SVD（奇异值分解）近似模拟异形光圈散景，无需昂贵的完整 2D 卷积：

// Bokeh SVD: separable rank-r approximation of aperture kernel
// Precomputed U[rank][pixel], S[rank], V[rank][pixel] from SVD of target kernel
// Horizontal pass: for each rank r, weight = V[r][x] * S[r]
// Vertical pass:   for each rank r, weight = U[r][y]
// Bokeh size scales with rcp(CoC) — wider CoC = larger bokeh disc

Eye Adaptation — Histogram-Based眼睛适应 — 基于直方图

eye_adaptation.hlsl offers two exposure computation methods. The histogram method uses a 64-bin histogram with percentile outlier removal for more robust metering in high-contrast scenes:

eye_adaptation.hlsl 提供两种曝光计算方法。直方图方法使用 64 个柱的直方图配合百分位异常值移除，在高对比度场景中实现更稳健的测光：

// Basic method: downsampled weighted average
float smoothedLum = lerp(prevLum, targetLum, 1 - exp2(-dt * AdaptSpeed));
exposure = LocalExposureMultipler / max(0.0001, smoothedLum);

// Histogram method: 64-bin log-luminance histogram
// ComputeAverageLuminanceWithoutOutlier:
//   remove bottom LowPercentile% and top HighPercentile% of histogram bins
//   compute weighted average of remaining bins

// AdaptationWeight(nx, slope): center-weighted metering
// triangle function: max(1 - 2*slope*|nx - 0.5|, 0)
// gives higher weight to center of frame

Color Grading — combine_lut.hlsl (677 lines)调色 — combine_lut.hlsl（677 行）

combine_lut.hlsl is the most complete color processing pass, baking a final 3D LUT that encodes white balance, film tone curve, Nuke-style color correction, gamut expansion, and device-specific output into a single texture lookup at runtime:

combine_lut.hlsl 是最完整的色彩处理 Pass，将白平衡、胶片色调曲线、Nuke 风格色彩校正、色域扩展和设备特定输出烘焙到单个 3D LUT 纹理，在运行时一次查找完成：

Final Composite — Everything in One Pass最终合成 — 单 Pass 完成所有

The final composite pass executes all remaining operations in sequence within a single full-screen quad draw. This avoids the bandwidth cost of separate passes for each effect:

最终合成 Pass 在单次全屏四边形绘制中按顺序执行所有剩余操作。这避免了每个效果独立 Pass 的带宽开销：

// final_composite.hlsl — execution order (simplified)
float4 ps_main(Fragment input) {
  float2 uv = input.uv;
  float3 color = FXAAPass(SceneColor, uv);   // FXAA 3.11 preset 5 (32 steps)
  color = DOFPass(color, uv, DOFBlur);       // Gaussian CoC blend
  color = BokehDOFPass(color, uv, bokehBuf); // SVD bokeh blend
  color += SunShaftPass(uv);                // additive volumetric shafts
  color += BloomPass(color, BloomTex)       // + dirty lens overlay
        + LensFlarePass(uv, sunPos);        // 8-ghost hexagon flare
  color = TonemapCommonPS(color, uv);       // ACES + color correct + LUT
  // Inside TonemapCommonPS:
  //   grain jitter (temporal noise) → chromatic aberration (CA fringe)
  //   → sharpen (neighbor luminance difference)
  //   → vignette (cos^4 law radial darkening)
  //   → grain intensity → color LUT lookup (3D unwrapped)
  //   → linear → sRGB gamma
  return float4(color, 1);
}

Effect Reference Table效果参考表