util={

    inside = function(x, y, rectangle)
        if x >= rectangle[1] and
           y >= rectangle[2] and
           x <  rectangle[3]+rectangle[1] and
           y <  rectangle[4]+rectangle[2] then
            return true
        else
            return false
        end
    end,

    aabb = function(sprite)
        local x = sprite.pos.x + sprite.bbo.left
        local y = sprite.pos.y + sprite.bbo.top
        local w = sprite.size.w - sprite.bbo.right - sprite.bbo.left
        local h = sprite.size.h - sprite.bbo.bottom - sprite.bbo.top
        return x, y, w, h
    end,

    check_aabb_collision = function(x1,y1,w1,h1, x2,y2,w2,h2)
        return ( x1 < x2 + w2 and x1 + w1 > x2 and y1 < y2 + h2 and y1 + h1 > y2 )
    end

}