Game Input mouse filtering

Question

I'm having a problem with filtering mouse inputs, the method I am doing right know moves the cursor back to the center of the screen each frame. But I cant do this because it messes with other things. Does anyone know how to implement this with delta mouse movement. Here is the relevant code.

void update() {
    static float oldX = 0;
    static float oldY = 0;
    static float walkSpeed = .05f;
    static float sensitivity = 0.002f;//mouse sensitivity
    static float smooth = 0.7f;//mouse smoothing (0.0 - 0.99)
    float w = ScreenResolution.x/2.0f;
    float h = ScreenResolution.y/2.0f;

    Vec2f scrc(w,h);
    Vec2f mpos(getMouseX(),getMouseY());

    float x = scrc.x-mpos.x;
    float y = scrc.y-mpos.y;

    oldX = (oldX*smooth + x*(1.0-smooth));
    oldY = (oldY*smooth + y*(1.0-smooth));

    x = oldX * sensitivity;
    y = oldY * sensitivity;

    camera->rotate(Vec3f(y,0,0));
    transform->setRotation(transform->getRotation()*Quaternionf::fromAxisAngle(0.0f,1.0f,0.0f,-x));

    setMousePosition((int)scrc.x,(int)scrc.y);//THIS IS THE PROBLEM LINE HOW CAN I AVOID THIS

    ....
}