add voronoi_penholder

examples/voronoi/voronoi_penholder.scad

@@ -0,0 +1,53 @@
+use <hull_polyline2d.scad>;
+use <shape_square.scad>;
+use <hollow_out.scad>;
+use <bend_extrude.scad>;
+use <experimental/voronoi2d_cells.scad>;
+
+xy = [100, 40];
+pt_nums = 20;
+thickness = 2;
+
+voronoi_penholder(xy, pt_nums, thickness);
+
+module voronoi_penholder(xy, pt_nums, thickness) {
+    xs1 = rands(0, xy[0], pt_nums);
+    ys1 = rands(0, xy[1], pt_nums);
+    points = [for(i = [0:len(xs1) - 1]) [xs1[i], ys1[i]]];
+
+    cpts = concat(
+        [for(p = points) if(p[0] > xy[0] - 10) p + [-xy[0], 0]],
+        points,
+        [for(p = points) if(p[0] < 10) p + [xy[0], 0]]
+    );
+
+    function default_region_size(points) = 
+        let(
+            xs = [for(p = points) p[0]],
+            ys = [for(p = points) abs(p[1])]
+        )
+        max([(max(xs) -  min(xs) / 2), (max(ys) -  min(ys)) / 2]);
+
+    size = default_region_size(cpts);  
+    region_shape = shape_square(size, corner_r = size / 5);
+
+    cells = voronoi2d_cells(cpts, region_shape);
+    bend_extrude(size = [xy[0], xy[1]], thickness = thickness, angle = 360, $fn = 48) 
+    {
+        for(i = [0:len(cpts) - 1]) {
+            cell = cells[i];
+            hull_polyline2d(concat(cell, [cell[0]]), width = thickness);
+            
+        }
+    }
+
+    r = 0.5 * xy[0] / PI;
+
+    linear_extrude(thickness)
+        circle(r, $fn = 48);
+
+    translate([0, 0, xy[1]])    
+    linear_extrude(thickness)
+    hollow_out(shell_thickness = thickness)
+        circle(r, $fn = 48);
+}