aperiodic: let user specify colors, add normals

1 files changed, 108 insertions, 32 deletions

diff --git a/aperiodic_tiling.cginc b/aperiodic_tiling.cginc
index 78c911d..5e12ee0 100644
--- a/aperiodic_tiling.cginc
+++ b/aperiodic_tiling.cginc
@@ -10,6 +10,8 @@
 #include "globals.cginc"
 #include "math.cginc"
 
+#if defined(_APERIODIC_TILING)
+
 static const float M5 = sqrt(2.0 / 5.0);
 
 static const float4 basis_u5_03 = M5 * float4(
@@ -41,60 +43,134 @@ float2x2 inv2x2(float2x2 m) {
   return float2x2(m[1][1], -m[0][1], -m[1][0], m[0][0]) / d;
 }
 
-// Test if point p lies in one candidate tile.
-// m: inverse of the forward (barycentric -> projected) matrix.
-// s: barycentric center of the candidate tile.
-// a, b: axis selectors for this face orientation.
-float tile5(float4 p03, float p44, float2x2 m, float2 s,
-            float4 a03, float a44, float4 b03, float b44) {
+struct AperiodicTileSample {
+  float coverage;
+  float2 barycentric;
+};
+
+float2 tile5_barycentric(float4 p03, float p44, float2x2 m, float2 s,
+                         float4 a03, float a44, float4 b03, float b44) {
   float2 q = mul(s, m);
   p03 -= (1.0 - a03 - b03) * round(q.x * basis_u5_03 + q.y * basis_v5_03);
   p44 -= (1.0 - a44 - b44) * round(q.x * basis_u5_44 + q.y * basis_v5_44);
-  float2 f = abs(mul(m, proj5(p03, p44)) - s);
-  return max(0.0, 0.5 - max(f.x, f.y));
+  return mul(m, proj5(p03, p44)) - s;
+}
+
+float tile5_distance_from_barycentric(float2 barycentric) {
+  float2 f = abs(barycentric);
+  return 0.5 - max(f.x, f.y);
+}
+
+float aperiodic_edge_coverage(float distance_to_edge) {
+  float edge_width = saturate(_Aperiodic_Tiling_Edge_Thickness * 2.0) * 0.5;
+  float signed_distance = distance_to_edge - edge_width;
+  float aa_width = max(fwidth(signed_distance), 1e-4);
+  return smoothstep(-aa_width, aa_width, signed_distance);
 }
 
-// Test all 4 candidate tiles for one face orientation.
-// Returns barycentric distance to nearest edge (positive inside, zero outside).
-float t5(float4 p03, float p44, float4 a03, float a44, float4 b03, float b44) {
+#if defined(_APERIODIC_TILING_NORMALS)
+float3 aperiodic_tiling_normal(float2 barycentric) {
+  float bevel_width = min(_Aperiodic_Tiling_Normal_Thickness, 0.5);
+  if (bevel_width <= 1e-5) {
+    return float3(0.0, 0.0, 1.0);
+  }
+
+  float flat_limit = 0.5 - bevel_width;
+  float2 edge_factor = smoothstep(flat_limit, 0.5, abs(barycentric));
+  float2 xy = sign(barycentric) * edge_factor * _Aperiodic_Tiling_Normal_Strength;
+  return normalize(float3(xy, 1.0));
+}
+#endif  // _APERIODIC_TILING_NORMALS
+
+void choose_aperiodic_candidate(float2 barycentric, inout float distance_to_edge,
+                                inout float2 best_barycentric) {
+  float candidate_distance = tile5_distance_from_barycentric(barycentric);
+  if (candidate_distance > distance_to_edge) {
+    distance_to_edge = candidate_distance;
+    best_barycentric = barycentric;
+  }
+}
+
+AperiodicTileSample sample_aperiodic_orientation(
+    float4 p03, float p44, float4 a03, float a44, float4 b03, float b44) {
   float2 pa = proj5(a03, a44);
   float2 pb = proj5(b03, b44);
   float2x2 m = inv2x2(float2x2(pa.x, pb.x, pa.y, pb.y));
   float2 r = round(float2(dot5(p03, p44, a03, a44), dot5(p03, p44, b03, b44)));
   float2 s = float2(0.5, -0.5);
-  return tile5(p03, p44, m, r + s.xx, a03, a44, b03, b44) +
-         tile5(p03, p44, m, r + s.xy, a03, a44, b03, b44) +
-         tile5(p03, p44, m, r + s.yx, a03, a44, b03, b44) +
-         tile5(p03, p44, m, r + s.yy, a03, a44, b03, b44);
+
+  float2 best_barycentric = tile5_barycentric(p03, p44, m, r + s.xx, a03, a44, b03, b44);
+  float distance_to_edge = tile5_distance_from_barycentric(best_barycentric);
+  choose_aperiodic_candidate(
+      tile5_barycentric(p03, p44, m, r + s.xy, a03, a44, b03, b44),
+      distance_to_edge, best_barycentric);
+  choose_aperiodic_candidate(
+      tile5_barycentric(p03, p44, m, r + s.yx, a03, a44, b03, b44),
+      distance_to_edge, best_barycentric);
+  choose_aperiodic_candidate(
+      tile5_barycentric(p03, p44, m, r + s.yy, a03, a44, b03, b44),
+      distance_to_edge, best_barycentric);
+
+  AperiodicTileSample sample;
+  sample.coverage = aperiodic_edge_coverage(distance_to_edge);
+  sample.barycentric = best_barycentric;
+  return sample;
+}
+
+void apply_aperiodic_orientation(float3 face_color,
+                                 float4 p03, float p44,
+                                 float4 a03, float a44, float4 b03, float b44,
+                                 float3 edge_color,
+                                 inout float3 albedo, inout float2 normal_xy_acc) {
+  AperiodicTileSample sample =
+      sample_aperiodic_orientation(p03, p44, a03, a44, b03, b44);
+  albedo += (face_color - edge_color) * sample.coverage;
+#if defined(_APERIODIC_TILING_NORMALS)
+  normal_xy_acc += aperiodic_tiling_normal(sample.barycentric).xy * sample.coverage;
+#endif
 }
 
-float3 dim5(float2 uv) {
+void sample_aperiodic_tiling(float2 uv, out float3 albedo
+                             , out float3 tiling_normal_tangent
+                             ) {
   float4 p03 = uv.x * basis_u5_03 + uv.y * basis_v5_03;
   float p44 = uv.x * basis_u5_44 + uv.y * basis_v5_44;
 
   float2 u = float2(0, 1);
-  float3 edge = float3(0.04, 0.1, 0.04);
-  float3 c = edge;
+  float3 edge = _Aperiodic_Tiling_Edge_Color.rgb;
+  albedo = edge;
+  float2 normal_xy_accum = 0;
 
   // 10 face orientations = C(5,2) pairs of 5D axes
-  c += (float3(0.4, 0.9, 0.4) - edge) * t5(p03, p44, u.yxxx, u.x, u.xyxx, u.x);
-  c += (float3(0.6, 0.7, 0.2) - edge) * t5(p03, p44, u.yxxx, u.x, u.xxyx, u.x);
-  c += (float3(0.3, 0.5, 0.0) - edge) * t5(p03, p44, u.yxxx, u.x, u.xxxy, u.x);
-  c += (float3(0.2, 0.3, 0.0) - edge) * t5(p03, p44, u.yxxx, u.x, u.xxxx, u.y);
-  c += (float3(0.0, 0.3, 0.2) - edge) * t5(p03, p44, u.xyxx, u.x, u.xxyx, u.x);
-  c += (float3(0.0, 0.5, 0.4) - edge) * t5(p03, p44, u.xyxx, u.x, u.xxxy, u.x);
-  c += (float3(0.2, 0.7, 0.6) - edge) * t5(p03, p44, u.xyxx, u.x, u.xxxx, u.y);
-  c += (float3(0.3, 0.6, 0.0) - edge) * t5(p03, p44, u.xxyx, u.x, u.xxxy, u.x);
-  c += (float3(0.0, 0.4, 0.0) - edge) * t5(p03, p44, u.xxyx, u.x, u.xxxx, u.y);
-  c += (float3(0.0, 0.6, 0.3) - edge) * t5(p03, p44, u.xxxy, u.x, u.xxxx, u.y);
-
-  return c;
+  apply_aperiodic_orientation(_Aperiodic_Tiling_Color_0.rgb, p03, p44, u.yxxx, u.x, u.xyxx, u.x, edge, albedo, normal_xy_accum);
+  apply_aperiodic_orientation(_Aperiodic_Tiling_Color_1.rgb, p03, p44, u.yxxx, u.x, u.xxyx, u.x, edge, albedo, normal_xy_accum);
+  apply_aperiodic_orientation(_Aperiodic_Tiling_Color_2.rgb, p03, p44, u.yxxx, u.x, u.xxxy, u.x, edge, albedo, normal_xy_accum);
+  apply_aperiodic_orientation(_Aperiodic_Tiling_Color_3.rgb, p03, p44, u.yxxx, u.x, u.xxxx, u.y, edge, albedo, normal_xy_accum);
+  apply_aperiodic_orientation(_Aperiodic_Tiling_Color_4.rgb, p03, p44, u.xyxx, u.x, u.xxyx, u.x, edge, albedo, normal_xy_accum);
+  apply_aperiodic_orientation(_Aperiodic_Tiling_Color_5.rgb, p03, p44, u.xyxx, u.x, u.xxxy, u.x, edge, albedo, normal_xy_accum);
+  apply_aperiodic_orientation(_Aperiodic_Tiling_Color_6.rgb, p03, p44, u.xyxx, u.x, u.xxxx, u.y, edge, albedo, normal_xy_accum);
+  apply_aperiodic_orientation(_Aperiodic_Tiling_Color_7.rgb, p03, p44, u.xxyx, u.x, u.xxxy, u.x, edge, albedo, normal_xy_accum);
+  apply_aperiodic_orientation(_Aperiodic_Tiling_Color_8.rgb, p03, p44, u.xxyx, u.x, u.xxxx, u.y, edge, albedo, normal_xy_accum);
+  apply_aperiodic_orientation(_Aperiodic_Tiling_Color_9.rgb, p03, p44, u.xxxy, u.x, u.xxxx, u.y, edge, albedo, normal_xy_accum);
+
+#if defined(_APERIODIC_TILING_NORMALS)
+  tiling_normal_tangent = normalize(float3(normal_xy_accum, 1.0));
+#else
+  tiling_normal_tangent = 0;
+#endif
 }
+#endif  // defined(_APERIODIC_TILING)
 
-void apply_aperiodic_tiling(float2 uv, inout float3 albedo) {
+void apply_aperiodic_tiling(float2 uv, inout float3 albedo, inout float3 normal_tangent) {
 #if defined(_APERIODIC_TILING)
   uv *= _Aperiodic_Tiling_Scale;
-  albedo = dim5(uv);
+  float3 tiling_normal_tangent;
+  sample_aperiodic_tiling(uv, albedo
+                          , tiling_normal_tangent
+                          );
+#if defined(_APERIODIC_TILING_NORMALS)
+  normal_tangent = blendNormalsHill12(normal_tangent, tiling_normal_tangent);
+#endif
 #endif  // _APERIODIC_TILING
 }