How to set (0, 0) coordinate position for GLFW window - c++

Question

I'm creating a GLFW window, and I would like the bottom left corner to be the origin. For some reason, the top left corner is the origin.
I should also mention that I'm using OSX.
Here's my window class:
#include "window.h"
namespace graphics {
void window_size_callback(GLFWwindow* window, int width, int height);
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode);
void mouse_button_callback(GLFWwindow* window, int button, int action, int mode);
void cursor_position_callback(GLFWwindow* window, double mouse_x, double mouse_y);
Window::Window(const char* title, int width, int height) {
m_title = title;
m_width = width;
m_height = height;
if (!init())
glfwTerminate();
}
Window::~Window() {
glfwTerminate();
}
bool Window::init() {
if (!glfwInit()) {
std::cout << "GLFW failed to initialize!" << std::endl;
return false;
}
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 2);
m_window = glfwCreateWindow(m_width, m_height, m_title, NULL, NULL);
if (!m_window) {
glfwTerminate();
std::cout << "GLFW failed to create a window!" << std::endl;
return false;
}
glfwMakeContextCurrent(m_window);
glfwSetWindowUserPointer(m_window, this);
glfwSetWindowSizeCallback(m_window, window_size_callback);
glfwSetKeyCallback(m_window, key_callback);
glfwSetMouseButtonCallback(m_window, mouse_button_callback);
glfwSetCursorPosCallback(m_window, cursor_position_callback);
if (glewInit() != GLEW_OK) {
std::cout << "GLEW failed to initialize!" << std::endl;
return false;
}
std::cout << "OpenGL Version: " << glGetString(GL_VERSION) << std::endl;
std::cout << "OpenGL Shading Language Version: " << glGetString(GL_SHADING_LANGUAGE_VERSION) << std::endl;
return true;
}
void Window::update() {
glfwPollEvents();
glfwSwapBuffers(m_window);
}
void Window::clear() const {
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
}
bool Window::isClosed() const {
return glfwWindowShouldClose(m_window);
}
bool Window::isKeyPressed(unsigned int keycode) const {
if (keycode >= MAX_KEYS)
return false;
return m_keys[keycode];
}
bool Window::isMouseButtonPressed(unsigned int button) const {
if (button >= MAX_BUTTONS)
return false;
return m_mouse_buttons[button];
}
void Window::getMousePosition(double& x, double& y) const {
x = m_mouse_x;
y = m_mouse_y;
}
void window_size_callback(GLFWwindow* window, int width, int height) {
Window* win = (Window*)glfwGetWindowUserPointer(window);
win->m_width = width;
win->m_height = height;
}
void key_callback(GLFWwindow* window, int key, int scancode, int action, int mode) {
Window* win = (Window*)glfwGetWindowUserPointer(window);
win->m_keys[key] = action != GLFW_RELEASE;
}
void mouse_button_callback(GLFWwindow* window, int button, int action, int mode) {
Window* win = (Window*)glfwGetWindowUserPointer(window);
win->m_mouse_buttons[button] = action != GLFW_RELEASE;
}
void cursor_position_callback(GLFWwindow* window, double mouse_x, double mouse_y) {
Window* win = (Window*)glfwGetWindowUserPointer(window);
win->m_mouse_x = mouse_x;
win->m_mouse_y = mouse_y;
}
}

Answer 1

http://www.opengl-tutorial.org/beginners-tutorials/tutorial-2-the-first-triangle/
But here is a better way to visualize this : use the Right Hand Rule
X is your thumb
Y is your index
Z is your middle finger. If you put
your thumb to the right and your index to the sky, it will point to
your back, too. Having the Z in this direction is weird, so why is it
so ? Short answer : because 100 years of Right Hand Rule Math will
give you lots of useful tools. The only downside is an unintuitive Z.
This is something you can’t change, it’s built in your graphics card.
So (-1,-1) is the bottom left corner of your screen. (1,-1) is the
bottom right, and (0,1) is the middle top. So this triangle should
take most of the screen.