camera_res_in_map.java

        //Update camera position
        //Camera.x - viewPort.width must > 0, or just set to 0
        //Camera.y - viewPort.height must > 0, or just set to 0

        //restrict 0, 0 side
        float cameraX = actor.getX() - (camera.viewportWidth / 2) > 0 ? actor.getX() : camera.viewportWidth / 2;
        float cameraY = actor.getY() - (camera.viewportHeight / 2) > 0 ? actor.getY() : camera.viewportHeight / 2;

        //restrict h, w side
        cameraX = actor.getX() + (camera.viewportWidth / 2) > mapSizeX ? mapSizeX - (camera.viewportWidth / 2) : cameraX;
        cameraY = actor.getY() + (camera.viewportHeight / 2) > mapSizeY ? mapSizeY - (camera.viewportHeight / 2) : cameraY;

// if v < a, return a; if v > b, return b; else keep v
float clamp(float v, float a, float b)
{
    return max(a, min(v, b));
}

float cameraX = clamp(actor.getX(), camera.viewportWidth / 2, mapSizeX - (camera.viewportWidth / 2) );
float cameraY = clamp(actor.getY(), camera.viewportHeight / 2, mapSizeY - (camera.viewportHeight / 2) );