On the issue of window size.

[GraphicsEnthusiast]

How should I set the actual window size to be the same as the window size created by glfw? I want the image in the bottom left corner to fill the screen.

[Klivess]

https://docs.gl/gl4/glViewport does this.

glViewport(0, 0, GLFWwindowWidth, GLFWwindowHeight);