MetalByTutorials/02-3d-models/README.md

Chapter 2: 3D Models

As I read this book, I summarize what I think is wrong. If you think my comments are wrong then please let me know. We can dicuss more and update your opinion.

Metal coordinate system

The book doesn't mention that The Metal NDC(Normalized Device Coordinate) system is the left-hand coordinate system.

To show the train, this book modified the model file itself. It's not bad but I believe that the model file should be remained to original. Instead of changing y position to -1, we can modify the vertex shader code like below and get the same result.

vertex float4 vertex_main(const VertexIn vertex_in [[ stage_in ]]) {
  float4 position = vertex_in.position;
  position.y -= 1.0;  // lower y position by -1
  return position;
}