begin roughing out marble gimmick

1 files changed, 15 insertions, 0 deletions

diff --git a/math.cginc b/math.cginc
index 4b91209..0d59121 100644
--- a/math.cginc
+++ b/math.cginc
@@ -4,6 +4,21 @@
 #define PI 3.14159265358979f
 #define RCP_PI (1.0f / PI)
 
+float sin_noise_3d(float3 uvw) {
+  return sin(uvw[0]) * sin(uvw[1]) * sin(uvw[2]);
+}
+
+float sin_noise_3d_fbm(float3 uvw, uint octaves, float k, float strength) {
+  float result = 0;
+  float factor = 1.0f;
+  for (uint i = 0; i < octaves; i++) {
+    result += sin_noise_3d(uvw) * factor * strength;
+    uvw *= k;
+    factor /= k;
+  }
+  return result;
+}
+
 // Wrap a dot product. Assume it's already clamped.
 // At k=0, you get standard lambertian shading.
 // At k=0.5, you get half-lambertian shading.