Add hollow helix example

README.md

@@ -46,6 +46,7 @@ The output consists of a series of images, each depicting a layer of the solid,
 | `torus1.solid` | Torus | A torus with a tube radius of s, and a hole radius of 2 * s |
 | `ramp.solid` | Ramp | A spiraling ramp |
 | `helix1.solid` | Helix | A helix |
+| `hhelix1.solid` | Hollow Helix | A hollow helix |
 | `rotating_triangle_torus.solid` | RTT | A triangle rotating 2π around the z axis |
 | `hollow_rtt.solid` | RTT | A hollow triangle rotating 2π around the z axis |
 | `rotating_triangle_torus2.solid` | RTT | A triangle rotating 4π around the z axis |

examples/helix1.solid

@@ -3,8 +3,8 @@
 define @b (3 * s) / 2
 define @a @b / π
 
--5*s <= x <= 5*s
--5*s <= y <= 5*s
+-4*s <= x <= 4*s
+-4*s <= y <= 4*s
 -s <= z <= 2*s
 
 (ρ - 3*s)^2 + (z - @b  - (@a * φ))^2 <= s^2 \

examples/hhelix1.solid

@@ -0,0 +1,20 @@
+# Helix with radius s, inner radius 2s
+
+define @b (3 * s) / 2
+define @a @b / π
+
+-4*s <= x <= 4*s
+-4*s <= y <= 4*s
+-s <= z <= 2*s
+
+{(ρ - 3*s)^2 + (z - @b  - (@a * φ))^2 <= s^2 \
+∨ \
+(ρ - 3*s)^2 + (z - 3*s - @b  - (@a * φ))^2 <= s^2 \
+∨ \
+(ρ - 3*s)^2 + (z + 3*s - @b  - (@a * φ))^2 <= s^2} \
+⊻ \
+{(ρ - 3*s)^2 + (z - @b  - (@a * φ))^2 <= (s-1)^2 \
+∨ \
+(ρ - 3*s)^2 + (z - 3*s - @b  - (@a * φ))^2 <= (s-1)^2 \
+∨ \
+(ρ - 3*s)^2 + (z + 3*s - @b  - (@a * φ))^2 <= (s-1)^2}