diff --git a/game/src/engine/math.rs b/game/src/engine/math.rs
index ad19d52..6e11ace 100644
--- a/game/src/engine/math.rs
+++ b/game/src/engine/math.rs
@@ -1,8 +1,9 @@
 use std::ops::{Add, AddAssign, Mul, MulAssign};
 
+#[derive(Clone, Copy, PartialEq, Debug)]
 pub struct V2(pub f64, pub f64);
 
-#[derive(Copy, Clone)]
+#[derive(Clone, Copy, PartialEq, Debug)]
 pub struct V3(pub f64, pub f64, pub f64);
 
 impl Add for V3 {
@@ -39,41 +40,28 @@ impl V3 {
     }
 }
 
-pub struct Vertex(V3, V3, V3);
+#[derive(Clone, PartialEq, Debug)]
+pub struct Vertex(pub V3, pub V3, pub V3);
 
-pub struct Cube {
-    vertices: [Vertex; 12],
-}
+#[cfg(test)]
+mod test {
+    use super::*;
 
-impl Cube {
-    pub fn new(V3(x, y, z): V3, V3(w, h, d): V3) -> Self {
-        Self {
-            vertices: [
-                Vertex(V3(x, y, z), V3(x, y + h, z), V3(x + w, y + h, z)),
-                Vertex(V3(x + w, y + h, z), V3(x + w, y, z), V3(x, y + h, z)),
-                Vertex(V3(x + w, y, z), V3(x + w, y + h, z), V3(x + w, y, z + d)),
-                Vertex(
-                    V3(x + w, y + h, z + d),
-                    V3(x + w, y, z + d),
-                    V3(x, y + h, z + d),
-                ),
-                Vertex(V3(x, y + h, z), V3(x + w, y + h, z), V3(x, y + h, z + d)),
-                Vertex(
-                    V3(x + w, y + h, z),
-                    V3(x + w, y + h, z + d),
-                    V3(x, y + h, z + d),
-                ),
-                Vertex(V3(x, y, z), V3(x, y + h, z), V3(x, y, z + d)),
-                Vertex(V3(x, y + h, z), V3(x, y + h, z + d), V3(x, y, z + d)),
-                Vertex(V3(x, y, z), V3(x + w, y, z), V3(x, y, z + d)),
-                Vertex(V3(x + w, y, z), V3(x + w, y, z + d), V3(x, y, z + d)),
-                Vertex(V3(x, y, z + d), V3(x + w, y, z + d), V3(x, y + h, z + d)),
-                Vertex(
-                    V3(x + w, y, z + d),
-                    V3(x + w, y + h, z + d),
-                    V3(x, y + h, z + d),
-                ),
-            ],
-        }
+    #[test]
+    fn v3_ops() {
+        let v2 = |v: f64| V2(v, v);
+        let v3 = |v: f64| V3(v, v, v);
+
+        assert_eq!(v3(1.0) + v3(2.0), v3(3.0));
+
+        let mut a = v3(1.0);
+        a += v3(2.0);
+        assert_eq!(a, v3(3.0));
+
+        assert_eq!(v3(2.0) * 2.0, v3(4.0));
+
+        let mut a = v3(2.0);
+        a *= 2.0;
+        assert_eq!(a, v3(4.0));
     }
 }
diff --git a/game/src/engine/mod.rs b/game/src/engine/mod.rs
index d48e81b..be969fd 100644
--- a/game/src/engine/mod.rs
+++ b/game/src/engine/mod.rs
@@ -2,6 +2,7 @@ mod error;
 mod game;
 pub mod math;
 mod sdl_io;
+pub mod shapes;
 mod system;
 
 pub use game::{Event, Game, Io, Object, Renderer};
diff --git a/game/src/engine/shapes.rs b/game/src/engine/shapes.rs
new file mode 100644
index 0000000..38f8dd3
--- /dev/null
+++ b/game/src/engine/shapes.rs
@@ -0,0 +1,50 @@
+use crate::engine::math::{Vertex, V3};
+
+pub struct Shape {
+    vertices: Vec<V3>,
+    fragments: Vec<(usize, usize, usize)>,
+}
+
+impl Shape {
+    pub fn new_cube(V3(x, y, z): V3, V3(w, h, d): V3) -> Self {
+        Self {
+            vertices: vec![
+                V3(x, y, z),             //  0 front top     left
+                V3(x + w, y, z),         //  1 front top     right
+                V3(x, y + h, z),         //  2 front bottom  left
+                V3(x + w, y + h, z),     //  3 front bottom  right
+                V3(x, y, z + d),         //  4 back  top     left
+                V3(x + w, y, z + d),     //  5 back  top     right
+                V3(x, y + h, z + d),     //  6 back  bottom  left
+                V3(x + w, y + h, z + d), //  7 back  bottom  right
+            ],
+            fragments: vec![
+                // back
+                (0, 1, 2),
+                (3, 2, 1),
+                // bottom
+                (4, 5, 0),
+                (1, 0, 5),
+                // left
+                (4, 0, 6),
+                (2, 6, 0),
+                // front
+                (5, 4, 7),
+                (6, 7, 4),
+                // top
+                (7, 6, 3),
+                (2, 3, 6),
+                // right
+                (1, 5, 3),
+                (7, 3, 5),
+            ],
+        }
+    }
+
+    pub fn iter<'a>(&'a self) -> impl Iterator<Item = Vertex> + 'a {
+        let verts: &[V3] = &self.vertices;
+        self.fragments
+            .iter()
+            .map(|(a, b, c)| Vertex(verts[*a], verts[*b], verts[*c]))
+    }
+}
diff --git a/game/src/main.rs b/game/src/main.rs
index 1fc203a..37da723 100644
--- a/game/src/main.rs
+++ b/game/src/main.rs
@@ -1,4 +1,5 @@
 #![allow(dead_code)]
+#![allow(unused)]
 
 use std::time::Duration;