Add quantization to rim lighting

Good for artistic effect.

4 files changed, 21 insertions, 1 deletions

diff --git a/Editor/tooner.cs b/Editor/tooner.cs
index 9190f0f..7063972 100644
--- a/Editor/tooner.cs
+++ b/Editor/tooner.cs
@@ -371,6 +371,11 @@ public class ToonerGUI : ShaderGUI {
           bc,
           "Rim lighting emission");
 
+      bc = FindProperty($"_Rim_Lighting{i}_Quantization");
+      editor.FloatProperty(
+          bc,
+          "Rim lighting quantization");
+
       bc = FindProperty($"_Rim_Lighting{i}_Glitter_Enabled");
       enabled = bc.floatValue > 1E-6;
       EditorGUI.BeginChangeCheck();
diff --git a/globals.cginc b/globals.cginc
index 6f7d459..e4708c0 100644
--- a/globals.cginc
+++ b/globals.cginc
@@ -193,6 +193,7 @@ float _Rim_Lighting0_Center;
 float _Rim_Lighting0_Power;
 float _Rim_Lighting0_Strength;
 float _Rim_Lighting0_Emission;
+float _Rim_Lighting0_Quantization;
 #if defined(_RIM_LIGHTING0_GLITTER)
 float _Rim_Lighting0_Glitter_Enabled;
 float _Rim_Lighting0_Glitter_Density;
@@ -212,6 +213,7 @@ float _Rim_Lighting1_Center;
 float _Rim_Lighting1_Power;
 float _Rim_Lighting1_Strength;
 float _Rim_Lighting1_Emission;
+float _Rim_Lighting1_Quantization;
 #if defined(_RIM_LIGHTING1_GLITTER)
 float _Rim_Lighting1_Glitter_Enabled;
 float _Rim_Lighting1_Glitter_Density;
diff --git a/tooner.shader b/tooner.shader
index 938a922..b747945 100644
--- a/tooner.shader
+++ b/tooner.shader
@@ -150,6 +150,7 @@ Shader "yum_food/tooner"
     _Rim_Lighting0_Power("Rim lighting power", Float) = 2.0
     _Rim_Lighting0_Strength("Rim lighting strength", Float) = 1.0
     _Rim_Lighting0_Emission("Rim lighting emission", Float) = 0
+    _Rim_Lighting0_Quantization("Rim lighting quantization", Float) = -1
     _Rim_Lighting0_Glitter_Enabled("Rim lighting glitter", Float) = 0
     _Rim_Lighting0_Glitter_Density("Rim lighting glitter density", Float) = 100
     _Rim_Lighting0_Glitter_Amount("Rim lighting glitter amount", Float) = 100
@@ -165,6 +166,7 @@ Shader "yum_food/tooner"
     _Rim_Lighting1_Power("Rim lighting power", Float) = 2.0
     _Rim_Lighting1_Strength("Rim lighting strength", Float) = 1.0
     _Rim_Lighting1_Emission("Rim lighting emission", Float) = 0
+    _Rim_Lighting1_Quantization("Rim lighting quantization", Float) = -1
     _Rim_Lighting1_Glitter_Enabled("Rim lighting glitter", Float) = 0
     _Rim_Lighting1_Glitter_Density("Rim lighting glitter density", Float) = 100
     _Rim_Lighting1_Glitter_Amount("Rim lighting glitter amount", Float) = 100
diff --git a/tooner_lighting.cginc b/tooner_lighting.cginc
index 7fbe4d1..1fddfca 100644
--- a/tooner_lighting.cginc
+++ b/tooner_lighting.cginc
@@ -325,7 +325,10 @@ float get_glitter(float2 uv, float3 worldPos,
     float3 normal, float density, float amount, float speed,
     float mask, float brightness, float angle, float power)
 {
-  precise float idensity = rcp(density);
+  // A regular divide here causes flickering. The leading guess is that NVIDIA
+  // hardware implements the divide instruction slightly differently on
+  // different cores.
+  precise float idensity = 1.0 / density;
   float glitter = rand2(floor(uv * density) * idensity);
 
   float thresh = 1 - amount / 100;
@@ -772,6 +775,10 @@ float4 effect(inout v2f i)
     {
       float rl = abs(theta) / PI;  // on [0, 1]
       rl = pow(2, -_Rim_Lighting0_Power * abs(rl - _Rim_Lighting0_Center));
+      float q = _Rim_Lighting0_Quantization;
+      if (q > -1) {
+        rl = floor(rl * q) / q;
+      }
       float3 matcap = rl * _Rim_Lighting0_Color * _Rim_Lighting0_Strength;
 #if defined(_RIM_LIGHTING0_MASK)
       float4 matcap_mask_raw = _Rim_Lighting0_Mask.SampleGrad(linear_repeat_s, i.uv.xy, iddx, iddy);
@@ -824,6 +831,10 @@ float4 effect(inout v2f i)
     {
       float rl = abs(theta) / PI;  // on [0, 1]
       rl = pow(2, -_Rim_Lighting1_Power * abs(rl - _Rim_Lighting1_Center));
+      float q = _Rim_Lighting1_Quantization;
+      if (q > 0) {
+        rl = floor(rl * q) / q;
+      }
       float3 matcap = rl * _Rim_Lighting1_Color * _Rim_Lighting1_Strength;
 #if defined(_RIM_LIGHTING1_MASK)
       float4 matcap_mask_raw = _Rim_Lighting1_Mask.SampleGrad(linear_repeat_s, i.uv.xy, iddx, iddy);