From d4a703fffb2de50d43c25c4b607b7c7b252fd70e Mon Sep 17 00:00:00 2001
From: yum <yum.food.vr@gmail.com>
Date: Mon, 15 Jul 2024 00:36:05 -0700
Subject: Add Toon shading mode

Same as "realistic" except spherical harmonics all get the same normal.
Approach derived from Poiyomi Toon shader.
---
 Editor/tooner.cs |  3 ++-
 pbr.cginc        | 46 ++++++++++++++++++++++++----------------------
 poi.cginc        | 40 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 66 insertions(+), 23 deletions(-)

diff --git a/Editor/tooner.cs b/Editor/tooner.cs
index e7fdf6b..adc0fca 100644
--- a/Editor/tooner.cs
+++ b/Editor/tooner.cs
@@ -476,7 +476,8 @@ public class ToonerGUI : ShaderGUI {
   enum NormalsMode {
     Flat,
     Spherical,
-    Realistic
+    Realistic,
+    Toon
   };
 
   void DoShadingMode() {
diff --git a/pbr.cginc b/pbr.cginc
index 44e0b88..581df3f 100644
--- a/pbr.cginc
+++ b/pbr.cginc
@@ -97,12 +97,11 @@ float3 BoxProjection (
 	float4 cubemapPosition, float3 boxMin, float3 boxMax
 ) {
 	#if UNITY_SPECCUBE_BOX_PROJECTION
-		UNITY_BRANCH
 		if (cubemapPosition.w > 0) {
 			float3 factors =
 				((direction > 0 ? boxMax : boxMin) - position) / direction;
 			float scalar = min(min(factors.x, factors.y), factors.z);
-			direction = direction * scalar + (position - cubemapPosition);
+			direction = direction * scalar + (position - cubemapPosition.xyz);
 		}
 	#endif
 	return direction;
@@ -120,7 +119,11 @@ UnityIndirect CreateIndirectLight(float4 vertexLightColor, float3 view_dir, floa
   // Avatars are not static, don't use lightmap.
   indirect.diffuse = 0;
 #else
-  indirect.diffuse += max(0, ShadeSH9(float4(normal, 1)));
+  if (_Mesh_Normals_Mode == 3) {  // Toon
+    indirect.diffuse += max(0, BetterSH9(float4(0, 0, 0, 1)));
+  } else {
+    indirect.diffuse += max(0, BetterSH9(float4(normal, 1)));
+  }
 #endif
   float3 reflect_dir = reflect(-view_dir, normal);
   Unity_GlossyEnvironmentData env_data;
@@ -133,38 +136,37 @@ UnityIndirect CreateIndirectLight(float4 vertexLightColor, float3 view_dir, floa
   float3 probe0 = Unity_GlossyEnvironment(
       UNITY_PASS_TEXCUBE(unity_SpecCube0), unity_SpecCube0_HDR, env_data
       );
-  env_data.reflUVW = BoxProjection(
-      reflect_dir, worldPos,
-      unity_SpecCube1_ProbePosition,
-      unity_SpecCube1_BoxMin, unity_SpecCube1_BoxMax
-      );
+  indirect.specular = probe0;
 #if UNITY_SPECCUBE_BLENDING
-  float interpolator = unity_SpecCube0_BoxMin.w;
-  UNITY_BRANCH
-    if (interpolator < 0.99999) {
-      float3 probe1 = Unity_GlossyEnvironment(
-          UNITY_PASS_TEXCUBE_SAMPLER(unity_SpecCube1, unity_SpecCube0),
-          unity_SpecCube0_HDR, env_data
-          );
-      indirect.specular = lerp(probe1, probe0, interpolator);
-    }
-    else {
-      indirect.specular = probe0;
-    }
+  if (unity_SpecCube0_BoxMin.w < 0.99999) {
+    env_data.reflUVW = BoxProjection(
+        reflect_dir, worldPos,
+        unity_SpecCube1_ProbePosition,
+        unity_SpecCube1_BoxMin, unity_SpecCube1_BoxMax
+        );
+    float3 probe1 = Unity_GlossyEnvironment(
+        UNITY_PASS_TEXCUBE_SAMPLER(unity_SpecCube1, unity_SpecCube0),
+        unity_SpecCube0_HDR, env_data
+        );
+    indirect.specular = lerp(probe1, probe0, unity_SpecCube0_BoxMin.w);
+  }
 #else
   indirect.specular = probe0;
 #endif  // UNITY_SPECCUBE_BLENDING
 
+  // Lifted from poi toon shader (MIT).
+  float horizon = min(1 + dot(reflect_dir, normal), 1);
+  indirect.specular *= horizon * horizon;
+
 #if defined(_CUBEMAP)
   float roughness = GetRoughness(smoothness);
-  probe0 =
+  indirect.specular =
     UNITY_SAMPLE_TEXCUBE_LOD(
         _Cubemap,
         reflect_dir,
         roughness * UNITY_SPECCUBE_LOD_STEPS);
 #endif  // _CUBEMAP
 
-  indirect.specular = probe0;
 #endif  // FORWARD_BASE_PASS
 
   indirect.diffuse *= ao;
diff --git a/poi.cginc b/poi.cginc
index 5e31a42..1d2b846 100644
--- a/poi.cginc
+++ b/poi.cginc
@@ -57,4 +57,44 @@ float3 HSVtoRGB(in float3 HSV)
   return ((RGB - 1) * HSV.y + 1) * HSV.z;
 }
 
+float shEvaluateDiffuseL1Geomerics_local(float L0, float3 L1, float3 n)
+{
+  // average energy
+  float R0 = max(0, L0);
+
+  // avg direction of incoming light
+  float3 R1 = 0.5f * L1;
+
+  // directional brightness
+  float lenR1 = length(R1);
+
+  // linear angle between normal and direction 0-1
+  //float q = 0.5f * (1.0f + dot(R1 / lenR1, n));
+  //float q = dot(R1 / lenR1, n) * 0.5 + 0.5;
+  float q = dot(normalize(R1), n) * 0.5 + 0.5;
+  q = saturate(q); // Thanks to ScruffyRuffles for the bug identity.
+
+  // power for q
+  // lerps from 1 (linear) to 3 (cubic) based on directionality
+  float p = 1.0f + 2.0f * lenR1 / R0;
+
+  // dynamic range constant
+  // should vary between 4 (highly directional) and 0 (ambient)
+  float a = (1.0f - lenR1 / R0) / (1.0f + lenR1 / R0);
+
+  return R0 * (a + (1.0f - a) * (p + 1.0f) * pow(q, p));
+}
+
+half3 BetterSH9(half4 normal)
+{
+  float3 indirect;
+  float3 L0 = float3(unity_SHAr.w, unity_SHAg.w, unity_SHAb.w) + float3(unity_SHBr.z, unity_SHBg.z, unity_SHBb.z) / 3.0;
+  indirect.r = shEvaluateDiffuseL1Geomerics_local(L0.r, unity_SHAr.xyz, normal.xyz);
+  indirect.g = shEvaluateDiffuseL1Geomerics_local(L0.g, unity_SHAg.xyz, normal.xyz);
+  indirect.b = shEvaluateDiffuseL1Geomerics_local(L0.b, unity_SHAb.xyz, normal.xyz);
+  indirect = max(0, indirect);
+  indirect += SHEvalLinearL2(normal);
+  return indirect;
+}
+
 #endif  // __POI_INC
-- 
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