add hollow_out_vase

examples/hollow_out/hollow_out_vase.scad

@@ -0,0 +1,66 @@
+use <hull_polyline3d.scad>;
+use <bezier_curve.scad>;
+use <rotate_p.scad>;
+use <paths2sections.scad>;
+use <experimental/hollow_out_sweep.scad>;
+use <experimental/tri_bisectors.scad>;
+
+t_step = 0.1;
+width = 3;
+fn = 18;
+line_style = "HULL_LINES"; // [LINES, HULL_LINES]
+
+p0 = [30, 0, 0];
+p1 = [80, 0, 50];
+p2 = [0, 0, 60];
+p3 = [25, 0, 120];
+p4 = [35, 0, 130];
+
+hollow_out_vase([p0, p1, p2, p3, p4], t_step, width, fn, line_style);
+
+module hollow_out_vase(ctrl_pts, t_step, width, fn, line_style) {
+    bezier = bezier_curve(t_step, 
+        ctrl_pts
+    );
+    
+    fpt = ctrl_pts[len(ctrl_pts) - 1];
+
+    a_step = 360 / fn;
+    sects = paths2sections([
+        for(a = [0:a_step:360 - a_step])
+        [for(p = bezier) rotate_p(p, [0, 0, a])]
+    ]);
+    
+    // body
+    hollow_out_sweep(sects, thickness = width, style = line_style, $fn = 4);
+
+    leng_sect = len(sects[0]);
+
+    // bottom
+    fst_sect = sects[0];
+    fst_tris = concat(
+        [for(i = [0:leng_sect - 2]) [[0, 0, 0], fst_sect[i], fst_sect[i + 1]]],
+        [[[0, 0, 0], fst_sect[leng_sect - 1], fst_sect[0]]]
+    );
+    for(tri = fst_tris) {
+        lines = tri_bisectors(tri);
+        for(line = lines) {
+            hull_polyline3d(line, thickness = width, $fn = 4);
+        }
+        hull_polyline3d([lines[2][1], [0, 0, 0]], thickness = width, $fn = 4);
+    }
+
+    // mouth
+    lst_sect = sects[len(sects) - 1];
+    lst_tris = concat(
+        [for(i = [0:leng_sect - 2]) [[0, 0, fpt[2]], lst_sect[i], lst_sect[i + 1]]],
+        [[[0, 0,  fpt[2]], lst_sect[leng_sect - 1], lst_sect[0]]]
+    );
+    dangling_pts = [for(tri = lst_tris) tri_bisectors(tri)[1][1]];
+    offset_z = [0, 0, width];
+    for(i = [0: leng_sect - 1]) {
+       hull_polyline3d([lst_sect[i] + offset_z, dangling_pts[i]], thickness = width, $fn = 4);
+       hull_polyline3d([lst_sect[(i + 1) % leng_sect] + offset_z, dangling_pts[i]], thickness = width, $fn = 4);   
+    }
+        
+}