1 files changed, 4 insertions, 2 deletions
diff --git a/hittable.go b/hittable.go
index 42599ab..ac5e996 100644
--- a/hittable.go
+++ b/hittable.go
@@ -11,12 +11,14 @@ type HitRecord struct {
   P Vec3
   N Vec3
   T float64
+  F bool
   Mat Material
 }
 
 func (rec *HitRecord) SetFaceNormal(r Ray, out_n Vec3) {
-  if r.Direction.Dot(out_n) < 0 {
-    rec.N = out_n
+  rec.F = r.Direction.Dot(out_n) < 0;
+  if rec.F {
+    rec.N = out_n;
   } else {
     rec.N = out_n.Neg();
   }