I'm writing a Metal app for iPhone. I have tons of OpenGL experience, so it shouldn't be too hard, right?
WRONG.
I'm rendering this 2d scene of rectangles with no aspect ratio correction - the vertices are in [-1,1] x [-1,1] coordinates, so this should fill the entire screen and distort the scene to fit the screen.
BTW, this is running on a relatively new iPhone, version 12.1.2 (16C101).
In landscape mode (width > height), this is what I get (screencapped image): https://i.sstatic.net/L3y9H.jpg. Half of the screen is blank.
In portrait mode (height > width), I get exactly what I expected (distorted squares): https://i.sstatic.net/wdF8k.jpg.
I think what is happening is that Metal just renders the portrait mode, and clips whatever goes off the screen, without "squishing" it to the screen viewport.
The code is just basic metal code, no configuration. I took the default Metal iOS project, removed the code in Renderer, and followed the Hello Triangle tutorial with uniforms sent to the shader and different vertex data.
How should I go about fixing this "bug"? Is it even a bug?
Figured it out!
I guess in func mtkView(_ view: MTKView, drawableSizeWillChange size: CGSize), I have to add the line metalLayer.frame = view.layer.frame and it works.
