I’m currently using GLWF as my window library, but i want to use SDL2 because it also supports iOS. The Youtube tutorial wasn't that helpfull, I managed to open a window with OpenGL but i ran into some problems:

Edit: i fixed this

In GLFW there is this command glfwGetFramebufferSize(window, &screenWidth, &screenHeight); but i can’t find a similar command in SDL2. 

I printed out the framebuffer-size and it was twice the size of my window, so i used it in my SDL2 project and it works, but the spotlight of the camera is not in the middle of the screen and everything is slightly distorted.

Keyboard inputs are only registered with a delay and the mouse isn’t working that good either.

This is how it looks like: https://www.youtube.com/watch?v=HFR2ZbWmcAg