Use of generic parameter directly where possible in structures instead of Box'd values. Added Material implementations for Box<Material> and Arc<Material> to aid in the automatic conversion when necessary to use a Sized value for Material. Implement From trait for [f32;3] to Vec3 to make some APIs Into<Vec3> which is a bit nicer to use.
What?
Implementations of the concepts explored by Peter Shirley in "Ray Tracing in One Weekend"