Add fog gimmick

1 files changed, 92 insertions, 0 deletions

diff --git a/noise.cginc b/noise.cginc
new file mode 100644
index 0000000..a58e56d
--- /dev/null
+++ b/noise.cginc
@@ -0,0 +1,92 @@
+#include "math.cginc"
+
+#ifndef __NOISE_INC
+#define __NOISE_INC
+
+float cubic_interp(float x)
+{
+  return x * x * (3.0 - 2.0 * x);
+}
+
+float2 cubic_interp(float2 x)
+{
+  return x * x * (3.0 - 2.0 * x);
+}
+
+float3 cubic_interp(float3 x)
+{
+  return x * x * (3.0 - 2.0 * x);
+}
+
+float quintic_interp(float x)
+{
+  return x * x * x * (x * (x * 6 - 15) + 10);
+}
+
+float2 quintic_interp(float2 x)
+{
+  return x * x * x * (x * (x * 6 - 15) + 10);
+}
+
+float perlin_noise(float2 p)
+{
+  float2 sq = floor(p);
+  float2 sqi = frac(p);
+
+  float r0 = rand2(sq + float2(0,0));
+  float r1 = rand2(sq + float2(1,0));
+  float r2 = rand2(sq + float2(0,1));
+  float r3 = rand2(sq + float2(1,1));
+
+  float2 u = cubic_interp(sqi);
+
+  return lerp(r0, r1, u.x) +
+    (r2 - r0) * u.y * (1.0 - u.x) +
+    (r3 - r1) * u.x * u.y;
+}
+
+float perlin_noise_3d(float3 p)
+{
+  float3 sq = floor(p);
+  float3 sqi = frac(p);
+
+  float r0 = rand3(sq + float3(0,0,0));
+  float r1 = rand3(sq + float3(1,0,0));
+  float r2 = rand3(sq + float3(0,1,0));
+  float r3 = rand3(sq + float3(1,1,0));
+  float r4 = rand3(sq + float3(0,0,1));
+  float r5 = rand3(sq + float3(1,0,1));
+  float r6 = rand3(sq + float3(0,1,1));
+  float r7 = rand3(sq + float3(1,1,1));
+
+  float3 u = cubic_interp(sqi);
+
+  return lerp(
+      lerp(r0, r1, u.x) +
+        (r2 - r0) * u.y * (1.0 - u.x) +
+        (r3 - r1) * u.x * u.y,
+      lerp(r4, r5, u.x) +
+        (r6 - r4) * u.y * (1.0 - u.x) +
+        (r7 - r5) * u.x * u.y,
+      u.z);
+}
+
+float simplex_noise(float2 p)
+{
+  float2 sq = floor(p);
+  float2 sqi = frac(p);
+
+  float r0 = rand2(sq + float2(0,0));
+  float r1 = rand2(sq + float2(1,0));
+  float r2 = rand2(sq + float2(0,1));
+  float r3 = rand2(sq + float2(1,1));
+
+  float2 u = quintic_interp(sqi);
+
+  return lerp(r0, r1, u.x) +
+    (r2 - r0) * u.y * (1.0 - u.x) +
+    (r3 - r1) * u.x * u.y;
+}
+
+#endif  // __NOISE_INC
+