Glitter: parameterize neighbor loop iterations

4 files changed, 25 insertions, 9 deletions

diff --git a/3ner.shader b/3ner.shader
index 5cc10be..66dfee8 100755
--- a/3ner.shader
+++ b/3ner.shader
@@ -661,6 +661,8 @@ Shader "yum_food/3ner"
           [ThryToggle(_GLITTER)] _Glitter_Enabled("Enable", Float) = 0
           _Glitter_Amount("Amount", Range(0, 1)) = 0.5
           _Glitter_Roughness("Roughness", Range(0.001, 0.1)) = 0.01
+          [IntRange] _Glitter_Spatial_Neighbor_Count("Spatial Neighbor Count", Range(1, 4)) = 4
+          [IntRange] _Glitter_Angular_Neighbor_Count("Angular Neighbor Count", Range(1, 4)) = 4
           _Glitter_Tint("Tint", Color) = (1, 1, 1, 1)
         [HideInInspector] m_end_Glitter("Glitter", Float) = 0
         //endex
diff --git a/glitter.cginc b/glitter.cginc
index 022b176..0588446 100644
--- a/glitter.cginc
+++ b/glitter.cginc
@@ -169,9 +169,14 @@ float3 disk_to_ndf_ggx(float2 v_disk, float alpha) {
   return float3(alpha * hemi.xy, hemi.z) / denom;
 }
 
+float2 GlitterNeighborOffset(float index) {
+  return float2(frac(index * 0.5) * 2.0, floor(index * 0.5)) - 0.5;
+}
+
 // Algorithm 1 from Kemppinen et. al.
 float D_Kemppinen(float3 h, float alpha, float glint_alpha, float2 uv,
-    float2x2 uv_J, float N, float filter_size, out float3 micro_normal) {
+    float2x2 uv_J, float N, float filter_size, float angular_neighbor_count,
+    float spatial_neighbor_count, out float3 micro_normal) {
   float res = sqrt(N);
   float2 x_s = uv;
   float3 x_a_and_d = ndf_to_disk_ggx(h, alpha);
@@ -199,13 +204,13 @@ float D_Kemppinen(float3 h, float alpha, float glint_alpha, float2 uv,
 
     float2 base_i_a = clamp(round(x_a * res_a), 1, res_a-1);
     [loop]
-    for (uint j_a = 0; j_a < 4; ++j_a) {
-      float2 i_a = base_i_a + float2(int2(j_a, j_a/2)%2)-.5;
+    for (float j_a = 0.0; j_a < angular_neighbor_count; j_a += 1.0) {
+      float2 i_a = base_i_a + GlitterNeighborOffset(j_a);
 
       float2 base_i_s = round(x_s * res_s);
       [loop]
-      for (uint j_s = 0; j_s < 4; ++j_s) {
-        float2 i_s = base_i_s + float2(int2(j_s, j_s/2)%2)-.5;
+      for (float j_s = 0.0; j_s < spatial_neighbor_count; j_s += 1.0) {
+        float2 i_s = base_i_s + GlitterNeighborOffset(j_s);
 
         float2 g_s = (i_s + Rand2D(i_s, i_a, l, 1u) - .5) / res_s;
         float2 g_a = (i_a + Rand2D(i_s, i_a, l, 2u) - .5) / res_a;
@@ -241,6 +246,7 @@ struct LightGlitter {
 // Glitter data getter to be run from lighting code.
 LightGlitter GetGlitterLighting(
     float glitter_amount, float glitter_roughness,
+    float glitter_spatial_neighbor_count, float glitter_angular_neighbor_count,
     float2 uv, float3x3 tbn, float roughness,
     float3 normal, float3 V, float3 direct_H, float3 indirect_dir) {
   LightGlitter g;
@@ -252,19 +258,23 @@ LightGlitter GetGlitterLighting(
   float3 direct_H_tangent = mul(direct_H, transpose(tbn));
   float3 direct_micro_normal;  // unused
   g.direct_D = D_Kemppinen(direct_H_tangent, roughness, glitter_roughness,
-      uv, uv_J, N, glitter_filter_size, direct_micro_normal);
+      uv, uv_J, N, glitter_filter_size,
+      glitter_angular_neighbor_count, glitter_spatial_neighbor_count,
+      direct_micro_normal);
 
   // Indirect
   float3 indirect_H = normalize(V + indirect_dir);
   float3 indirect_H_tangent = mul(indirect_H, transpose(tbn));
   float3 indirect_micro_normal;  // unused, but required by D_Kemppinen
   g.indirect_D = D_Kemppinen(indirect_H_tangent, roughness, glitter_roughness,
-      uv, uv_J, N, glitter_filter_size, indirect_micro_normal);
+      uv, uv_J, N, glitter_filter_size,
+      glitter_angular_neighbor_count, glitter_spatial_neighbor_count,
+      indirect_micro_normal);
   g.indirect_NoL = max(1e-4, dot(normal, indirect_dir));
   g.indirect_LoH = max(1e-4, dot(indirect_dir, indirect_H));
 
   return g;
 }
-#endif
+#endif  // _GLITTER
 
 #endif  // __GLITTER_INC
diff --git a/globals.cginc b/globals.cginc
index 88fb663..d3d8958 100755
--- a/globals.cginc
+++ b/globals.cginc
@@ -156,6 +156,8 @@ int _Details_UV_Channel;
 float _Glitter_Amount;
 float _Glitter_Roughness;
 float3 _Glitter_Tint;
+float _Glitter_Spatial_Neighbor_Count;
+float _Glitter_Angular_Neighbor_Count;
 #endif  // _GLITTER
 
 #if defined(_UV_SCROLL)
diff --git a/lighting.cginc b/lighting.cginc
index b6d3f8e..072e8d8 100755
--- a/lighting.cginc
+++ b/lighting.cginc
@@ -269,7 +269,9 @@ void GetLighting(v2f i, Pbr pbr, out LightData data) {
       data.indirect.L01g,
       data.indirect.L01b,
       data.indirect.dir);
-  data.glitter = GetGlitterLighting(_Glitter_Amount, _Glitter_Roughness,
+  data.glitter = GetGlitterLighting(
+      _Glitter_Amount, _Glitter_Roughness,
+      _Glitter_Spatial_Neighbor_Count, _Glitter_Angular_Neighbor_Count,
       i.uv01.xy, pbr.tbn, pbr.roughness,
       pbr.normal, data.common.V, data.direct.H, glitter_indirect_dir);
 #endif