Linking error in C++

Question

I'm just putting the finishing touches on a project I've been working on to render a scene in OpenGL - I based some of it on some old code I wrote for a Camera class (since I didn't want to have to re-figure out the maths!), however I'd included the Camera class as part of main.cpp before, and I wanted to move it to it's own seperate .h/.cpp files for the sake of reusability/clarity/general good practice.

I also replaced a basic Struct to hold the x and y position of the mouse with a Mouse class that I wrote.

I changed some code in the Windows Message Handler to have the Camera update when the Left Mouse Button is released - however I am getting a strange linking error -

1>main.obj : error LNK2001: unresolved external symbol "public: void __thiscall Camera::moveCamera(int,int,int,int)" (?moveCamera@Camera@@QAEXHHHH@Z)

The code in the Windows Message Handler is -

    case WM_LBUTTONUP:
        Mouse.SetPos(lParam); 
        x_mouse_end = Mouse.GetXPos();
        y_mouse_end = Mouse.GetYPos(); 
        Camera.moveCamera(x_mouse_start, y_mouse_start, x_mouse_end, y_mouse_end);
        SetCamera(); 
        break;

The parameters I'm passing to Camera.moveCamera() are integers as they are supposed to be.

The moveCamera() function is as follows -

//Moves the camera based on a user dragging the mouse 
inline void Camera::moveCamera(int old_x, int old_y, int new_x, int new_y)
{
    //To store the differences between the old and new mouse positions 
    int x_difference, y_difference; 

    //If the mouse was dragged to the right, move the camera right
    if(new_x > old_x)
    {
        x_difference = new_x - old_x;
        x_difference = x_difference / 25;

        if(yaw > 350)
        {
            yaw = 0;
        }
        else
        {
            yaw = yaw + x_difference;
        }
    }

    //If the mouse was dragged to the left, move the camera left
    if(new_x < old_x)
    {
        x_difference = old_x - new_x;
        x_difference = x_difference / 25;

        if(yaw < 10)
        {
            yaw = 360;
        }
        else
        {
            yaw = yaw - x_difference;
        }
    }

    //If the mouse was dragged down, move the camera down
    if(new_y < old_y)
    {
        y_difference = new_y - old_y;
        y_difference = y_difference / 20;

        if(pitch < 10)
        {
            pitch = 360;
        }
        else
        {
            pitch = pitch - y_difference;
        }
    }

    //If the mouse was dragged up, move the camera up
    if(new_y > old_y)
    {
        y_difference = old_y - new_y;
        y_difference = y_difference / 20;
        if(pitch > 350)
        {
            pitch = 0;
        }
        else
        {
            pitch = pitch + y_difference;
        }
    }

    //Update the camera position based on the new Yaw, Pitch and Roll
    cameraUpdate();

}

"camera.h" is included as it should be, as is "mouse.h", and instances of both classes are set up -

Mouse Mouse;
Camera Camera;

I'm at a loss as to what could be missing.

Please let me know if you would like more information.

Answer 1

Maybe you included that definition of moveCamera() in a .cpp file with the " inline " keyword. This may be interpreted that this method is local to the .cpp in which it is defined. Try removing the inline .