diff --git c/Cargo.lock i/Cargo.lock
index 9b8929c..8e1e923 100644
--- c/Cargo.lock
+++ i/Cargo.lock
@@ -303,6 +303,7 @@ dependencies = [
  "lodepng",
  "loop9",
  "natord",
+ "num-traits",
  "pbr",
  "quick-error",
  "resize",