From 03c6eff81b3a9034f2a8e8caaad84cdc29b29f23 Mon Sep 17 00:00:00 2001
From: yum <yum.food.vr@gmail.com>
Date: Sat, 2 Nov 2024 18:42:25 -0700
Subject: hack: Apply interleaved gradient noise to direct light

This minimizes color banding due to dim direct lighting
---
 pbr.cginc | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/pbr.cginc b/pbr.cginc
index d795267..e4e5ff1 100644
--- a/pbr.cginc
+++ b/pbr.cginc
@@ -347,6 +347,21 @@ float4 getLitColor(
     screenPos = float4(i.screenPos, 0, i.pos.w);
   #endif
 
+// TODO optimize this
+// Break up color banding by adding some dithering to direct light.
+{
+  float2 screen_uv;
+  {
+    float3 full_vec_eye_to_geometry = i.worldPos - _WorldSpaceCameraPos;
+    float3 world_dir = normalize(i.worldPos - _WorldSpaceCameraPos);
+    float perspective_divide = 1.0 / i.pos.w;
+    float perspective_factor = length(full_vec_eye_to_geometry * perspective_divide);
+    screen_uv = i.screenPos.xy * perspective_divide;
+  }
+  uint2 screen_uv_round = floor(screen_uv * _ScreenParams.xy);
+  direct_light.color += ign(screen_uv_round) * 0.00390625;
+}
+
 #if 1
   float reflection_strength = _ReflectionStrength;
 #if defined(_REFLECTION_STRENGTH_TEX)
-- 
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