1 files changed, 30 insertions, 2 deletions
diff --git a/pbr.cginc b/pbr.cginc
index f172a98..dcb94c8 100755
--- a/pbr.cginc
+++ b/pbr.cginc
@@ -125,8 +125,36 @@ void propagateSmoothness(inout Pbr pbr) {
 void apply_marble(float3 world_pos, inout float3 albedo) {
 #if defined(_MARBLE)
   float3 uvw = world_pos * _Marble_Scale;
-  float3 noise = _Marble_Noise.Sample(aniso4_trilinear_repeat_s, uvw).rgb;
-  albedo = noise.x;
+
+  float3 noises[10];
+
+  float3 noise = 0;
+  float gain = 1;
+
+  float3 offset = 0;
+#if defined(_MARBLE_TIME)
+  offset += _Time[0] * _Marble_Speed * _Marble_Direction;
+#endif
+#if defined(_MARBLE_OFFSET)
+  offset += _Marble_Offset;
+#endif
+
+  uvw += offset;
+
+  for (uint ii = 0; ii < _Marble_Octaves; ++ii) {
+    noises[ii] = _Marble_Noise.Sample(aniso4_trilinear_repeat_s, uvw + noise * _Marble_Strength).rgb * gain;
+    noise += noises[ii];
+
+    uvw *= _Marble_Lacunarity;
+    gain *= _Marble_Gain;
+  }
+
+  // In general, the series 1 + r + ... + r^{n-1} = (1 - r^n) / (1 - r)
+  noise *= (1 - _Marble_Gain) / (1 - pow(_Marble_Gain, _Marble_Octaves));
+
+  noise = _Marble_Post_Ramp.Sample(linear_clamp_s, float2(noise.x, 0));
+
+  albedo = noise;
 #endif
 }