add pnoise2_demo

src/experimental/demo/pnoise2_demo.scad

@@ -0,0 +1,48 @@
+use <util/rand.scad>;
+use <function_grapher.scad>;
+use <experimental/pnoise2.scad>;
+
+module demo1() {
+    points = [
+        for(y = [0:.2:10])
+            for(x = [0:.2:10])
+                [x, y]
+    ];
+    noise = pnoise2(points);
+    
+    for(i = [0:len(points) - 1]) {
+        c = (noise[i] + 1.1) / 2;
+        color([c, c, c])
+        translate(points[i])
+            square(.2, center = true);
+    }
+}
+
+
+module demo2() {
+    points = [
+        for(y = [0:.2:10])
+            [
+                for(x = [0:.2:10])
+                [x, y]
+            ]
+    ];
+
+    seed = rand(0, 256);
+    function_grapher(
+        [
+            for(ri = [0:len(points) - 1])
+                let(ns = pnoise2(points[ri], seed))
+                    [
+                        for(ci = [0:len(ns) - 1])
+                            [points[ri][ci][0], points[ri][ci][1], ns[ci]]
+                    ]
+        ], 
+        0.25)
+    ;
+}
+
+demo1();
+
+translate([12, 0]) 
+    demo2();