Add tetrahedron

README.md

@@ -44,6 +44,8 @@ The output consists of a series of images, each depicting a layer of the solid,
 | --- | --- | --- |
 | `cube.solid` | Cube | A cube stood on its vertex |
 | `hcube.solid` | Hollow Cube | A hollow cube stood on its vertex |
+| `tetrahedron1.solid` | Tetrahedron | A tetrahedron stood on its edge |
+| `htetra1.solid` | Hollow Teterahedron | A hollow tetrahedron stood on its edge |
 | `sphere.solid` | Sphere | A sphere of radius s |
 | `torus1.solid` | Torus | A torus with a tube radius of s, and a hole radius of 2 * s |
 | `ramp.solid` | Ramp | A spiraling ramp |

examples/htetra1.solid

@@ -0,0 +1,16 @@
+# Hollow Tetrahedron
+
+define @ns s - 2
+
+-s < x < s
+-s < y < s
+-s < z < s
+
+{(x - s) + (y - s) - (z - s) < 0 ∧ \
+(x - s) - (y + s) + (z + s) < 0 ∧ \
+-(x + s) + (y - s) + (z + s) < 0 ∧ \
+-(x + s) - (y + s) - (z - s) < 0} ⊻ \
+{(x - @ns) + (y - @ns) - (z - @ns) < 0 ∧ \
+(x - @ns) - (y + @ns) + (z + @ns) < 0 ∧ \
+-(x + @ns) + (y - @ns) + (z + @ns) < 0 ∧ \
+-(x + @ns) - (y + @ns) - (z - @ns) < 0}

examples/tetrahedron1.solid

@@ -0,0 +1,10 @@
+# Tetrahedron
+
+-s < x < s
+-s < y < s
+-s < z < s
+
+(x - s) + (y - s) - (z - s) < 0
+(x - s) - (y + s) + (z + s) < 0
+-(x + s) + (y - s) + (z + s) < 0
+-(x + s) - (y + s) - (z - s) < 0