Question: I am in the process of making a simple racing game using Apple's SceneKit library. I have modeled a left turn section of the race track. I am able to successfully load the model into an SCNGeometry that I can then render. However, I would like to be able to use this model for both a left and right turn segment. To do this, I need to mirror the SCNGeometry over the y-z plane, though I can't for the life of me figure out how.

In SpriteKit, one can mirror a sprite by setting the corresponding SKNode's scale to -1. However, if I set the SCNGeometry's SCNNode's x scale to -1, the SCNGeometry will not render at all. While I can mirror the model in my modeling software, I would prefer not to have two basically identical models. Any suggestions would be appreciated.

Answer: 
Alright, turns out setting the SCNNode's x scale to -1 does in fact mirror the SCNGeometry.The issue is, when an SCNGeometry is mirrored that way, all of the faces are pointed inwards instead of outwards so none are rendered. If the object's material is changed so that the front faces are culled instead of the back faces, the SCNGeometry will be mirrored as expected.
When you scale the geometry to any "-" negative it flip the normals face. the default for normal faces are "One sided"
Set the "Material" property to "Double Sided"

with swift it might look like this

```
yourNode.geometry?.firstMaterial?.doubleSided = true

```