Metal-Tutorial | LWJGL OpenGL Tutorials by Thin Matrix | iOS library

Quoting from this forum question

OpenGL uses different clip-space coordinates than Metal (in GL, z goes from -1 to 1, while in Metal z goes from 0 to 1), so using GLKMatrix4MakePerspective doesn't give you a matrix that properly transforms from eye space to clip space. Instead, it transforms half of the viewing volume behind the eye, causing sometimes-subtle clipping and culling issues. You can fix up the matrix you get back from GLK by setting the matrix elements that are relevant to depth by adding the following code to makePerspectiveViewAngle:

let zs = farZ / (nearZ - farZ)

q[2][2] = zs

q[3][2] = zs * nearZ

You would typically use a new render command encoder for each frame. Anything you did with the previous render command encoder, like setting vertex buffers or fragment textures, is "lost" when that encoder is ended and you drop any references to it. So, yes, you need to set buffers and textures again.

However, that should not be expensive. Both of those methods just put a reference to the buffer or texture into a table. It's cheap. If you haven't modified their contents on the CPU, no data has to be copied. It shouldn't cause any state compilation, either. (Apple has said a design goal of Metal is to avoid any implicit state compilation. It's all explicit, such as when creating a render pipeline state object from a render pipeline descriptor.)

You need to profile your app to figure out what's limiting your frame rate, rather than guessing.