glfwSetCursorPosCallback to function in another class

Question

I\'m really stuck:

I have the mainWindow and in the main game loop I do:

// poll for input
glfwPollEvents();

this->controls->handleInput(windo         


        

Answer 1

An alternative solution would be to associate a pointer to controls to the GLFWindow. See glfwSetWindowUserPointer.

The pointer can be retrieved at an time form the GLFWWindow object by glfwGetWindowUserPointer. Of course the return type is void* and has to be casted to Controls*.

Instead of the global function or static method a Lambda expressions can be used. e.g:

glfwSetWindowUserPointer(window, this->controls);

glfwSetCursorPosCallback( window, [](GLFWwindow *window, double x, double y)
{
    if (Controls *controls = static_cast<Controls*>(glfwGetWindowUserPointer(window)))
        controls->handleMouse(window, x, y);
} );

Answer 2

You can't pass a class's member function as a function. glfwSetCursorPosCallback it's expecting a function and throwing the error because it gets a member function.

In other words your expected to provide a global function and pass that to glfwSetCursorPosCallback.

If you really want the controls object to get the cursor position callback you could store an instance of Controls in a global variable and pass on the callback to that instance. Something like this:

static Controls* g_controls;

void mousePosWrapper( double x, double y )
{
    if ( g_controls )
    {
        g_controls->handleMouse( x, y );
    }
}

Then when you call glfwSetCursorPosCallback you can pass the mousePosWrapper function:

glfwSetCursorPosCallback( window, mousePosWrapper );

Answer 3

My solution: Do not use the callback-setter. Instead I do the following:

glfwPollEvents();

this->controls->handleInput(window, mainObj);
this->controls->handleMouse(window, mainObj);

And within handleMouse I do:

GLdouble xPos, yPos;
glfwGetCursorPos(window, &xPos, &yPos);