add 2d voronoi noise

1 files changed, 35 insertions, 3 deletions

diff --git a/math.cginc b/math.cginc
index b79d9b6..514d21f 100755
--- a/math.cginc
+++ b/math.cginc
@@ -213,8 +213,39 @@ float3 domain_warp_3d_tex(Texture3D noise_tex, SamplerState s, float3 uvw,
   return noise;
 }
 
-// Return distance to the nearest cell edge in a Voronoi pattern.
-float voronoi_edge_distance(float3 x) {
+// 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) {
+  float2 x_floor = floor(x);
+  float2 x_frac = frac(x);
+  float d1 = 1e6;
+  float d2 = 1e6;
+  float2 p1 = 0;
+  float2 p2 = 0;
+
+  for (int j = -1; j <= 1; j++) {
+    for (int i = -1; i <= 1; i++) {
+      float2 cell_offset = float2(i, j);
+      float2 r = cell_offset + hash22_fast(x_floor + cell_offset) - x_frac;
+      float d = dot(r, r);
+      if (d < d1) {
+        d2 = d1;
+        p2 = p1;
+        d1 = d;
+        p1 = r;
+      } 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 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_3d(float3 x) {
   float3 x_floor = floor(x);
   float3 x_frac = frac(x);
   float d1 = 1e6;
@@ -240,7 +271,8 @@ float voronoi_edge_distance(float3 x) {
       }
     }
   }
-  return (d2 - d1) / (2.0 * max(1e-4, length(p2 - p1)));
+  float d = (d2 - d1) / (2.0f * max(1e-4, length(p2 - p1)));
+  return max(0.0f, 0.5f - d);
 }
 
 float median(float3 x) {