diff --git a/benchmarks/passing/raytrace.rs b/benchmarks/passing/raytrace.rs
index 7c936658..7539007f 100644
--- a/benchmarks/passing/raytrace.rs
+++ b/benchmarks/passing/raytrace.rs
@@ -8,8 +8,10 @@ fn main(xpos: f64, ypos: f64, zpos: f64, width: f64, height: f64) {
     let num_triangles: i64 = 100;
     let mut first_point: [f64; 3] = [0.0; 3];
     // 100 triangles, 3 points per triangle
+    // hack: need a single point to initialize the array
     let mut triangles: [[f64; 3]; 300] = [first_point; 300];
 
+    // allocate the rest of the points
     let mut ind: i64 = 1;
     while ind < 300 {
         let mut next_point: [f64; 3] = [0.0; 3];
@@ -17,7 +19,7 @@ fn main(xpos: f64, ypos: f64, zpos: f64, width: f64, height: f64) {
         ind = ind + 1;
     }
 
-    //build_cube(xpos, ypos, width, height, triangles);
+    build_cube(xpos, ypos, width, height, triangles);
 
     let res: f64 = triangles[10][0];
     let mut ind: i64 = 0;
@@ -34,14 +36,90 @@ fn build_cube(xpos: f64, ypos: f64, width: f64, height: f64, triangles: [[f64; 3
     let num_rectangles: i64 = 25;
     let rect_width: f64 = width / 25.0;
 
+    // build the front face, clockwise triangles
     let mut i: i64 = 0;
     let mut ti: i64 = 0;
-    let cx: f64 = xpos + width / 2.0;
+    let mut cx: f64 = xpos + width / 2.0;
     while i < num_rectangles {
+        // top left corner
         triangles[ti][0] = cx;
         triangles[ti][1] = ypos;
         triangles[ti][2] = 0.0;
 
+        // top right corner
+        triangles[ti + 1][0] = cx + rect_width;
+        triangles[ti + 1][1] = ypos;
+        triangles[ti + 1][2] = 0.0;
+
+        // bottom left corner
+        triangles[ti + 2][0] = cx;
+        triangles[ti + 2][1] = ypos;
+        triangles[ti + 2][2] = -height;
+
+        ti = ti + 3;
+        // top right corner
+        triangles[ti][0] = cx + rect_width;
+        triangles[ti][1] = ypos;
+        triangles[ti][2] = 0.0;
+
+        // bottom right corner
+        triangles[ti + 1][0] = cx + rect_width;
+        triangles[ti + 1][1] = ypos;
+        triangles[ti + 1][2] = -height;
+
+        // bottom left corner
+        triangles[ti + 2][0] = cx;
+        triangles[ti + 2][1] = ypos;
+        triangles[ti + 2][2] = -height;
+
+        ti = ti + 3;
+        cx = cx + rect_width;
         i = i + 1;
     }
+
+    // build the top face
+    let mut i: i64 = 0;
+    let mut cx: f64 = xpos + width / 2.0;
+    while i < num_rectangles {
+        // front left corner
+        triangles[ti][0] = cx;
+        triangles[ti][1] = ypos;
+        triangles[ti][2] = 0.0;
+
+        // back left corner
+        triangles[ti + 1][0] = cx;
+        triangles[ti + 1][1] = ypos + height;
+        triangles[ti + 1][2] = 0.0;
+
+        // back right corner
+        triangles[ti + 2][0] = cx + rect_width;
+        triangles[ti + 2][1] = ypos + height;
+        triangles[ti + 2][2] = 0.0;
+
+        ti = ti + 3;
+        // front left corner
+        triangles[ti][0] = cx;
+        triangles[ti][1] = ypos;
+        triangles[ti][2] = 0.0;
+
+        // back right corner
+        triangles[ti + 1][0] = cx + rect_width;
+        triangles[ti + 1][1] = ypos + height;
+        triangles[ti + 1][2] = 0.0;
+
+        // front right corner
+        triangles[ti + 2][0] = cx + rect_width;
+        triangles[ti + 2][1] = ypos;
+        triangles[ti + 2][2] = 0.0;
+
+        ti = ti + 3;
+        cx = cx + rect_width;
+        i = i + 1;
+    }
+
+    //if !(ti == 300) {
+    // this should never happen
+    // TODO we can't put an error message here, it's ignored by the rs2bril compiler
+    //println!("{}", ti);
+    //}
 }