Actually I just noticed something else, i modified config.lua to be 1280X1920 and it worked fine, as if the ratio has always to be 320/480 which is 0.66667
local normalW, normalH = 1280, 1920
if not display then return end -- This is needed for dekstop app
-- This calculation extends the standard letterbox scaling
-- Using this point x = 0, y = 0 is always in the top left corner of the screen on all devices
-- And x = display.contentWidth, y = display.contentHeight is always in the bottom right corner
local w, h = display.pixelWidth, display.pixelHeight
local scale = math.max(normalW / w, normalH / h)
w, h = w * scale, h * scale
application = {
content = {
width = w,
height = h,
scale = 'letterbox',
fps = 60,
imageSuffix = {
['@2x'] = 1.1,
--['@4x'] = 2.1
}
}
}