Shader modifiers have multiple entry points. Following this: http://wiki.unity3d.com/index.php?title=Silhouette-Outlined_Diffuse I should have two entry points, one after the Vertex shader (SCNShaderModifierEntryPointSurface) and the frag shader (SCNShaderModifierEntryPointFragment). Are these the correct entry points?
Also, if anyone has any tips on writing Metal shader code, that'd be greatly appreciated. Some general notes on how to translate it from the glsl shader would be amazing. Honestly, I've never had a problem reading code before, but this stuff is like Japanese to me.