add rock_horn

examples/voronoi/rock_horn.scad

@@ -0,0 +1,71 @@
+use <golden_spiral.scad>;
+use <sweep.scad>;
+use <noise/nz_worley3.scad>;
+use <shape_circle.scad>;
+use <ptf/ptf_rotate.scad>;
+
+detail = 4;
+seed = 5;
+
+rock_horn(detail, seed);
+
+module rock_horn(detail, seed) {
+    $fn = 64 * detail;
+    point_distance = 1 / detail;
+
+    scale = 4;
+    radius = 6;
+    thickness = 1.5;
+    
+    c = shape_circle(radius = radius);
+
+    pts_angles = golden_spiral(
+        from = 8, 
+        to = 8, 
+        point_distance = point_distance,
+        rt_dir = "CT_CLK"
+    );
+
+    leng = len(pts_angles);
+    scale_step = scale / leng;
+    h_step = 2 * scale * radius / leng;
+    sections = [
+        for(i = [0:leng - 1])
+        let(
+            pts = [
+                for(p = c) 
+                let(
+                    s = 1 + scale_step * i,
+                    nzp = [p.x * s, p.y * s, h_step * i],
+                    nz = nz_worley3(nzp.x, nzp.y, nzp.z, seed, radius, "border")
+                )
+                [nzp.x, nzp.y, 0] + [sign(p.x), sign(p.y), 0] * nz[3] / scale
+            ]
+        )
+        [
+            each pts,
+            each [
+                for(p = pts) 
+                p - [sign(p.x), sign(p.y), 0] * thickness
+            ]
+        ]
+    ] / scale;
+   
+    rx = [90, 0, 0];
+    sweep(
+        [
+            for(i = [0:leng - 1])
+            let(
+                section = sections[i],
+                pt_angle = pts_angles[i],
+                off = [pt_angle[0].x, pt_angle[0].y, 0],
+                a = pt_angle[1]
+            )
+            [
+                for(p = section)
+                off + ptf_rotate(ptf_rotate(p, rx), a)
+            ]
+        ], 
+        "HOLLOW"
+    );
+}