zebra: pull in phacelle noiseHEADmaster

1 files changed, 46 insertions, 8 deletions

diff --git a/math.cginc b/math.cginc
index 514d21f..0692440 100755
--- a/math.cginc
+++ b/math.cginc
@@ -110,7 +110,6 @@ float3 round_hex(float3 hex_coord) {
 float3 blendNormalsHill12(float3 n0, float3 n1) {
   n0.z += 1.0;
   n1.xy = -n1.xy;
-  
   return normalize(n0 * dot(n0, n1) - n1 * n0.z);
 }
 
@@ -213,19 +212,21 @@ float3 domain_warp_3d_tex(Texture3D noise_tex, SamplerState s, float3 uvw,
   return noise;
 }
 
-// Return distance to the nearest voronoi cell edge, clamped to [0, 0.5].
-// 0.5 is on the edge, 0 is far from it.
-float voronoi_d_2d(float2 x) {
+// Return distance to the nearest voronoi cell edge. Also returns p1 and p2,
+// vectors from the x to the nearest 2 lattice points, and p1_id, an identifier
+// for p1 which does not within the current cell.
+float voronoi_d_2d(float2 x, out float2 p1, out float2 p2, out float2 p1_id) {
   float2 x_floor = floor(x);
   float2 x_frac = frac(x);
   float d1 = 1e6;
   float d2 = 1e6;
-  float2 p1 = 0;
-  float2 p2 = 0;
+  p1 = 0;
+  p2 = 0;
 
   for (int j = -1; j <= 1; j++) {
     for (int i = -1; i <= 1; i++) {
       float2 cell_offset = float2(i, j);
+      // Radial vector from origin lattice point to current.
       float2 r = cell_offset + hash22_fast(x_floor + cell_offset) - x_frac;
       float d = dot(r, r);
       if (d < d1) {
@@ -233,14 +234,51 @@ float voronoi_d_2d(float2 x) {
         p2 = p1;
         d1 = d;
         p1 = r;
+        p1_id = x_floor + cell_offset;
       } else if (d < d2) {
         d2 = d;
         p2 = r;
       }
     }
   }
-  float d = (d2 - d1) / (2.0f * max(1e-4, length(p2 - p1)));
-  return max(0.0f, 0.5f - d);
+  return (d2 - d1);
+}
+
+// stripe_dir is the direction we want to draw stripes along. It must be
+// normalized.
+float4 phacelle_noise_2d(float2 x, float2 stripe_dir) {
+  float2 x_floor = floor(x);
+  float2 x_frac = frac(x);
+
+  float2 stripe_ortho = float2(-stripe_dir.y, stripe_dir.x) * TAU;
+
+  float2 vec = 0;
+  float normalization = 0;
+  for (int j = -1; j <= 2; j++) {
+    for (int i = -1; i <= 2; i++) {
+      float2 cell_offset = float2(i, j);
+      // Radial vector from origin lattice point to current.
+      float2 r = cell_offset + (hash22_fast(x_floor + cell_offset) - 0.5) * 0.5 - x_frac;
+      float d2 = dot(r, r);
+      // 0th cell is centered at 0.5.
+      float weight = max(0, exp(-2.0 * d2) - 0.01111);
+      normalization += weight;
+      float wave_input = dot(r, stripe_ortho);
+      // TODO what the fuck
+      // why is r not normalized
+      float vecs, vecc;
+      sincos(wave_input, vecs, vecc);
+      vec += float2(vecc, vecs) * weight;
+    }
+  }
+  vec /= normalization;
+  float magnitude = dot(vec, vec);
+  return float4(vec / magnitude, stripe_ortho);
+}
+
+float voronoi_d_2d(float2 x) {
+  float2 p1, p2, p1_id;
+  return voronoi_d_2d(x, p1, p2, p1_id);
 }
 
 // Return distance to the nearest voronoi cell edge, clamped to [0, 0.5].