add stick_tower

examples/stick_tower.scad

@@ -0,0 +1,83 @@
+include <line3d.scad>;
+
+/* [Basic] */
+
+stick_leng = 80;
+stick_thickness = 5;
+inner_square_leng = 60;
+leng_diff = 1.75;
+min_leng = 13;
+stick_fn = 24;
+
+/* [Advanced] */
+
+cap_style = "CAP_CIRCLE"; // [CAP_BUTT, CAP_CIRCLE, CAP_SPHERE]
+angle_offset = 5;
+layer_offset = 1.2;
+
+module stick_square(inner_square_leng, stick_leng, stick_thickness, cap_style) {
+    diff_leng = stick_leng - inner_square_leng;
+    half_inner_square_leng = inner_square_leng / 2;
+    half_stick_leng = stick_leng / 2;
+    
+    module stick() {
+        line3d(
+            [0, -half_stick_leng, 0], 
+            [0, half_stick_leng, 0], 
+            stick_thickness,
+            cap_style,
+            cap_style
+        );
+    }
+
+    module sticks() {
+        translate([-half_inner_square_leng, 0, 0])
+            stick();
+        translate([half_inner_square_leng, 0, 0])
+            stick();
+    }
+
+    sticks();
+    translate([0, 0, stick_thickness]) 
+        rotate(90) 
+            sticks();
+}
+    
+module spiral_stack(orig_leng, orig_height, current_leng, leng_diff, min_leng, angle_offset, pre_height = 0, i = 0) {
+    if(current_leng > min_leng) {
+        angle = atan2(leng_diff, current_leng - leng_diff);
+        
+        factor = current_leng / orig_leng;
+        
+        translate([0, 0, pre_height]) 
+            scale(factor) 
+                children();
+         
+        next_square_leng = sqrt(pow(leng_diff, 2) + pow(current_leng - leng_diff, 2));
+        
+        height = factor * orig_height + pre_height;
+        
+        rotate(angle + angle_offset)
+            spiral_stack(
+                orig_leng, 
+                orig_height, 
+                next_square_leng, 
+                leng_diff, 
+                min_leng,
+                angle_offset,                
+                height,
+                i + 1
+            ) children();
+    } 
+}
+
+height = stick_thickness * layer_offset;
+$fn = stick_fn;
+
+spiral_stack(inner_square_leng, stick_thickness * 2, inner_square_leng, leng_diff, min_leng, angle_offset)
+    stick_square(
+        inner_square_leng, 
+        stick_leng, 
+        height, 
+        cap_style
+    );