add pnoise2

src/experimental/_impl/_pnoise2_impl.scad

@@ -0,0 +1,36 @@
+use <experimental/_impl/_pnoise_comm.scad>;
+
+function _pnoise2_grad2(hashvalue, x, y) = 
+    let(case = hashvalue % 8)
+    case == 0 ? y :
+    case == 1 ? x + y :
+    case == 2 ? x:
+    case == 3 ? x - y:
+    case == 4 ? -y:
+    case == 5 ? -x - y:
+    case == 6 ? -x : -x + y;
+
+function _pnoise2(x, y, seed) =
+    let(
+        xi = floor(x),
+        yi = floor(y),
+        xf = x - xi,
+        yf = y - yi,
+        u = _pnoise_fade(xf),
+        v = _pnoise_fade(yf),
+        aa = _pnoise_lookup_poise_table(_pnoise_lookup_poise_table(seed + xi) + yi),
+        ba = _pnoise_lookup_poise_table(_pnoise_lookup_poise_table(seed + xi + 1) + yi),
+        ab = _pnoise_lookup_poise_table(_pnoise_lookup_poise_table(seed + xi) + yi + 1),
+        bb = _pnoise_lookup_poise_table(_pnoise_lookup_poise_table(seed + xi + 1) + yi + 1),
+        y1 = _pnoise_lerp(
+            _pnoise2_grad2(aa, xf, yf),
+            _pnoise2_grad2(ba, xf - 1, yf),
+            u
+        ),
+        y2 = _pnoise_lerp(
+            _pnoise2_grad2(ab, xf, yf - 1),
+            _pnoise2_grad2(bb, xf - 1, yf - 1),
+            u
+        )             
+    )
+    _pnoise_lerp(y1, y2, v);

src/experimental/pnoise2.scad

@@ -0,0 +1,6 @@
+use <util/rand.scad>;
+use <experimental/_impl/_pnoise2_impl.scad>;
+
+function pnoise2(points, seed) = 
+    let(sd = is_undef(seed) ? floor(rand(0, 256)) : seed % 256)
+    [for(p = points) _pnoise2(p[0], p[1], sd)];