OpenGL camera jumps suddenly at first mouse input? - c++

Question

I have been using OpenGL to create a 3D first person shooter game. I decided to abstract the camera movement to a separate player class and I have managed to get these methods to work but my only problem is that the camera makes a big jump whenever the mouse first enters the screen.
I know that the fix for this is to check for the first time mouse is moved but I have done this however it still causes a jump. Here is the code:
void player::mouse_input(double &mouse_x_coordinate, double &mouse_y_coordinate, bool &first_mouse)
{
if (first_mouse)
{
last_x = mouse_x_coordinate;
last_y = mouse_y_coordinate;
first_mouse = false;
}
float xoffset = mouse_x_coordinate - last_x;
float yoffset = last_y - mouse_y_coordinate;
last_x = mouse_x_coordinate;
last_y = mouse_y_coordinate;
xoffset *= sensitivity;
yoffset *= sensitivity;
yaw += xoffset;
pitch += yoffset;
if (pitch > 89.0f)
pitch = 89.0f;
if (pitch < -89.0f)
pitch = -89.0f;
glm::vec3 front;
front.x = cos(glm::radians(yaw)) * cos(glm::radians(pitch));
front.y = sin(glm::radians(pitch));
front.z = sin(glm::radians(yaw)) * cos(glm::radians(pitch));
a_forward_direction = glm::normalize(front);
}
the mouse_x_coordinate and mouse_y_coordinate parameters are global variables containing the mouses x and y coordinates which I got through the glfwSetCursorPosCallback() function.
The first_mouse Boolean is also a global variable initialised as true.
Here is the initialisation of the a_forward_direction vector:
glm::vec3 a_forward_direction = glm::vec3(0.0, 0.0, -1.0);
after following through the mouse_input method, I find that the values for front should match but it still causes a jump.
Can anyone tell me why the mouse still jumps?