Add brightness clamping to fog

Use a nice "almost identity" function to create a smooth transition to
the clamped value.

5 files changed, 42 insertions, 3 deletions

diff --git a/Editor/tooner.cs b/Editor/tooner.cs
index df3fa9d..2f87fb3 100644
--- a/Editor/tooner.cs
+++ b/Editor/tooner.cs
@@ -2087,6 +2087,8 @@ public class ToonerGUI : ShaderGUI {
     RangeProperty(bc, "Ray origin randomization");
     bc = FindProperty("_Gimmick_Fog_00_Lod_Half_Life");
     FloatProperty(bc, "LOD half life");
+    bc = FindProperty("_Gimmick_Fog_00_Max_Brightness");
+    RangeProperty(bc, "Max brightness");
     bc = FindProperty("_Gimmick_Fog_00_Noise");
     TexturePropertySingleLine(
         MakeLabel(bc, "3D Noise"),
diff --git a/fog.cginc b/fog.cginc
index 51b0936..5eb2145 100644
--- a/fog.cginc
+++ b/fog.cginc
@@ -220,6 +220,34 @@ float3 ACES(float3 x) {
   return saturate((x*(a*x+b))/(x*(c*x+d)+e));
 }
 
+// Clamp x to [0, k].
+// Assumes that x is already on [0, 1].
+float3 SmoothClamp(float3 x, float k) {
+  // Derivation of `b` from `k`:
+  //  f(x, b) = b * x / (x + b)
+  //  We want f(1, b) = k.
+  //  In other words, we want the max value the function can take on [0, 1] to
+  //  be k.
+  //   k = f(1, b)
+  //     = b / (1 + b)
+  //   b = k * (1 + b)
+  //     = k + kb
+  //   1 = k/b + k
+  //   1 - k = k/b
+  //   1/(1-k) = b/k
+  //   b = k/(1-k)
+  float e = 1E-4;
+  k = min(1-e, k);
+  float b = k/(1-k);
+  return b * x / (x + b);
+}
+float SmoothClamp(float x, float k) {
+  float e = 1E-4;
+  k = min(1-e, k);
+  float b = k/(1-k);
+  return b * x / (x + b);
+}
+
 Fog00PBR getFog00(v2f i, ToonerData tdata) {
   float3 cam_pos = _WorldSpaceCameraPos;
   float3 obj_pos = i.worldPos;
@@ -382,10 +410,17 @@ Fog00PBR getFog00(v2f i, ToonerData tdata) {
 
   Fog00PBR pbr;
   pbr.albedo = acc;
-  pbr.albedo.rgb = ACES(pbr.albedo.rgb);
 
   // Add some dithering to lit color to break up banding
-  pbr.albedo.rgb += ign(tdata.screen_uv_round) * .00390625;
+  //pbr.albedo.rgb += ign(tdata.screen_uv_round) * .00390625;
+
+  // Remap onto [0, 1]
+  pbr.albedo.rgb = ACES(pbr.albedo.rgb);
+  // Clamp so max brightness is comfortable. Do it in perceptually uniform
+  // space to avoid affecting saturation.
+  pbr.albedo.rgb = LRGBtoOKLAB(pbr.albedo.rgb);
+  pbr.albedo.x = SmoothClamp(pbr.albedo.x, _Gimmick_Fog_00_Max_Brightness);
+  pbr.albedo.rgb = OKLABtoLRGB(pbr.albedo.rgb);
 
   float4 clip_pos = mul(UNITY_MATRIX_VP, float4(ro, 1.0));
   pbr.depth = clip_pos.z / clip_pos.w;
diff --git a/globals.cginc b/globals.cginc
index 1c81c2b..b5b2160 100644
--- a/globals.cginc
+++ b/globals.cginc
@@ -758,6 +758,7 @@ float _Gimmick_Fog_00_Normal_Cutoff;
 float _Gimmick_Fog_00_Alpha_Cutoff;
 float _Gimmick_Fog_00_Ray_Origin_Randomization;
 float _Gimmick_Fog_00_Lod_Half_Life;
+float _Gimmick_Fog_00_Max_Brightness;
 texture3D _Gimmick_Fog_00_Noise;
 #if defined(_GIMMICK_FOG_00_NOISE_2D)
 texture2D _Gimmick_Fog_00_Noise_2D;
diff --git a/oklab.cginc b/oklab.cginc
index 337eb94..004dbc4 100644
--- a/oklab.cginc
+++ b/oklab.cginc
@@ -29,7 +29,7 @@
 #ifndef __OKLAB_INC
 #define __OKLAB_INC
 
-#if defined(_OKLAB) || defined(_GIMMICK_LETTER_GRID_COLOR_WAVE) || defined(_GIMMICK_AL_CHROMA_00_HUE_SHIFT) || defined(_GIMMICK_FOG_00_RAY_MARCH_0)
+#if defined(_OKLAB) || defined(_GIMMICK_LETTER_GRID_COLOR_WAVE) || defined(_GIMMICK_AL_CHROMA_00_HUE_SHIFT) || defined(_GIMMICK_FOG_00)
 
 // Utilities relating to the OKLAB color space, as defined here:
 //   https://bottosson.github.io/posts/oklab/
diff --git a/tooner.shader b/tooner.shader
index e47f35c..6cf6c68 100644
--- a/tooner.shader
+++ b/tooner.shader
@@ -662,6 +662,7 @@ Shader "yum_food/tooner"
     _Gimmick_Fog_00_Alpha_Cutoff("Albedo cutoff (alpha)", Range(0,1)) = 0.9
     _Gimmick_Fog_00_Ray_Origin_Randomization("Enable ray origin randomization", Range(0,1)) = 1
     _Gimmick_Fog_00_Lod_Half_Life("fog", Float) = 5
+    _Gimmick_Fog_00_Max_Brightness("max brightness", Range(0, 1)) = 1
 
     _Gimmick_Fog_00_Emitter_Texture("Emitter texture", 2D) = "black" {}
     _Gimmick_Fog_00_Emitter_Variable_Density("Enable emitter variable density", Float) = 0