From f53c49c69ee42917e3789bbfe792c9d53c287e76 Mon Sep 17 00:00:00 2001
From: yum <yum.food.vr@gmail.com>
Date: Tue, 3 Jun 2025 18:24:11 -0700
Subject: begin work on fog

---
 2ner.cginc     | 13 +++++++++++++
 2ner.shader    | 11 +++++++++++
 features.cginc |  4 ++++
 fog.cginc      | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 globals.cginc  |  8 ++++++++
 5 files changed, 84 insertions(+)
 create mode 100644 fog.cginc

diff --git a/2ner.cginc b/2ner.cginc
index 6cea852..6e2b6e6 100644
--- a/2ner.cginc
+++ b/2ner.cginc
@@ -9,6 +9,7 @@
 #include "face_me.cginc"
 #include "false_color_visualization.cginc"
 #include "features.cginc"
+#include "fog.cginc"
 #include "globals.cginc"
 #include "harnack_tracing.cginc"
 #include "interpolators.cginc"
@@ -183,6 +184,18 @@ float4 frag(v2f i, uint facing : SV_IsFrontFace
   i.tangent = UnityObjectToWorldNormal(i.tangent);
   i.binormal = UnityObjectToWorldNormal(i.binormal);
 
+#if defined(_RAYMARCHED_FOG)
+  FogParams fog_params = {
+    _Raymarched_Fog_Steps,
+    _Raymarched_Fog_Density,
+    _Raymarched_Fog_Dithering_Noise,
+    _Raymarched_Fog_Density_Noise,
+    _Raymarched_Fog_Density_Noise_Scale
+  };
+  FogResult fog_result = raymarched_fog(i, fog_params);
+  return fog_result.color;
+#endif
+
 #if defined(_SHATTER_WAVE) || defined(_TESSELLATION_HEIGHTMAP)
   calcNormalInScreenSpace(i.normal, i.objPos);
 #endif
diff --git a/2ner.shader b/2ner.shader
index 258db61..439da3b 100644
--- a/2ner.shader
+++ b/2ner.shader
@@ -816,6 +816,17 @@ Shader "yum_food/2ner"
           //endex
         [HideInInspector] m_end_Decals("Decals", Float) = 0
 
+        //ifex _Raymarched_Fog_Enabled==0
+        [HideInInspector] m_start_Raymarched_Fog("Raymarched fog", Float) = 0
+          [ThryToggle(_RAYMARCHED_FOG)] _Raymarched_Fog_Enabled("Enable", Float) = 0
+          _Raymarched_Fog_Steps("Steps", Range(1, 32)) = 32
+          _Raymarched_Fog_Density("Density", Float) = 1.0
+          _Raymarched_Fog_Dithering_Noise("Dithering noise", 2D) = "black" {}
+          _Raymarched_Fog_Density_Noise("Density noise", 3D) = "black" {}
+          _Raymarched_Fog_Density_Noise_Scale("Density noise scale", Vector) = (1, 1, 1, 0)
+        [HideInInspector] m_end_Raymarched_Fog("Raymarched fog", Float) = 0
+        //endex
+
         //ifex _3D_SDF_Enabled==0
         [HideInInspector] m_start_3D_SDF("3D SDF", Float) = 0
           [ThryToggle(_3D_SDF)] _3D_SDF_Enabled("Enable", Float) = 0
diff --git a/features.cginc b/features.cginc
index 5fcdfbf..40ed4a1 100644
--- a/features.cginc
+++ b/features.cginc
@@ -311,5 +311,9 @@
 #pragma shader_feature_local _DEPTH_PREPASS
 //endex
 
+//ifex _Raymarched_Fog_Enabled==0
+#pragma shader_feature_local _RAYMARCHED_FOG
+//endex
+
 #endif  // __FEATURES_INC
 
diff --git a/fog.cginc b/fog.cginc
new file mode 100644
index 0000000..c0800bc
--- /dev/null
+++ b/fog.cginc
@@ -0,0 +1,48 @@
+#ifndef __FOG_INC
+#define __FOG_INC
+
+#include "cnlohr.cginc"
+#include "interpolators.cginc"
+#include "globals.cginc"
+
+#if defined(_RAYMARCHED_FOG)
+
+struct FogParams {
+    float steps;
+    float density;
+    texture2D dithering_noise;
+    texture3D density_noise;
+    float4 density_noise_scale;
+};
+
+struct FogResult {
+    float4 color;
+};
+
+float getRayLengthWorld()
+{
+  float2 screen_uv;
+  float perspective_factor;
+  {
+    float3 full_vec_eye_to_geometry = i.worldPos - _WorldSpaceCameraPos;
+    float3 world_dir = normalize(i.worldPos - _WorldSpaceCameraPos);
+    float perspective_divide = 1.0 / i.pos.w;
+    perspective_factor = length(full_vec_eye_to_geometry * perspective_divide);
+    screen_uv = i.screenPos.xy * perspective_divide;
+  }
+  float eye_depth_world =
+    GetLinearZFromZDepth_WorksWithMirrors(
+        SAMPLE_DEPTH_TEXTURE(_CameraDepthTexture, screen_uv),
+        screen_uv) * perspective_factor;
+}
+
+FogResult raymarched_fog(v2f i, FogParams params)
+{
+    float3 ro = _WorldSpaceCameraPos;
+    float3 rd = normalize(i.worldPos - ray_pos);
+
+
+}
+
+#endif  // _RAYMARCHED_FOG
+#endif  // __FOG_INC
diff --git a/globals.cginc b/globals.cginc
index 1d9f291..80ba634 100644
--- a/globals.cginc
+++ b/globals.cginc
@@ -535,4 +535,12 @@ float4 _SSAO_Noise_TexelSize;
 float _SSAO_Bias;
 #endif  // _SSAO
 
+#if defined(_RAYMARCHED_FOG)
+float _Raymarched_Fog_Steps;
+float _Raymarched_Fog_Density;
+texture2D _Raymarched_Fog_Dithering_Noise;
+texture3D _Raymarched_Fog_Density_Noise;
+float4 _Raymarched_Fog_Density_Noise_Scale;
+#endif  // _RAYMARCHED_FOG
+
 #endif  // __GLOBALS_INC
-- 
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