it scrolls an image thing - using lpp-3ds - https://www.youtube.com/watch?v=d1AI4syhu1U

scroll.lua

Screen.enable3D()
Graphics.init()

-- this should always be below 1
friction = 0.9

-- these are set while the page is moving
y_position = 0
y_velocity = 0
dragging   = false

c_white    = Color.new(255, 255, 255)
c_grey     = Color.new(127, 127, 127)
c_blue     = Color.new(0, 0, 255)
c_red      = Color.new(255, 0, 0)
c_dark_red = Color.new(127, 0, 0)
c_black    = Color.new(0, 0, 0)
c_black_tl = Color.new(0, 0, 0, 50)

function createPage(func)
    local width, height = 320, 720
    local img = Screen.createImage(width, height, c_black)
    -- argument #3 to createImage seems to not work properly sometimes?
    Screen.fillRect(1, width, 1, height, c_dark_red, img)
    if func then
        func(img, width, height)
    end
    local gimg = Graphics.convertFrom(img)
    Screen.freeImage(img)
    return gimg, width, height
end

function drawDebug()
    Screen.debugPrint(5, 5, "y_position: "..y_position, c_white, BOTTOM_SCREEN)
    Screen.debugPrint(5, 20, "y_velocity: "..y_velocity, c_white, BOTTOM_SCREEN)
    Screen.debugPrint(5, 40, "friction: "..friction, c_white, BOTTOM_SCREEN)
    Screen.debugPrint(5, 55, "DRight: +0.05 - DLeft: -0.05", c_white, BOTTOM_SCREEN)
end

page1, page1_width, page1_height = createPage(function(img, width, height)
    Screen.debugPrint(5, 5, "Hello!", c_white, img)
    Screen.fillRect(70, 100, 245, 480, c_grey, img)
    Screen.debugPrint(20, 250, "Hello again!", c_white, img)
    Screen.debugPrint(50, 265, "This isn't a waste", c_white, img)
    Screen.fillRect(30, 60, 280, 320, c_white, img)
    Screen.fillRect(70, 100, 280, 480, c_grey, img)
    Screen.debugPrint(5, 550, "I should put sample text here", c_grey, img)
end)

frame = 0
while true do
    frame = frame + 1
    Screen.waitVblankStart()
    Screen.refresh()
    Screen.clear(TOP_SCREEN)
    Screen.clear(BOTTOM_SCREEN)
    lvl_3d = Screen.get3DLevel()
    pad = Controls.read()
    tx, ty = Controls.readTouch()

    touching = Controls.check(pad, KEY_TOUCH)
    showdebug = Controls.check(pad, KEY_L) or Controls.check(pad, KEY_R)
    if touching and not dragging then
        dragging = true
        y_velocity = 0
        otx, oty = tx, ty
    end
    if touching and dragging then
        y_position = math.min(math.max(y_position + (ty - oty), -page1_height + 240), 0)
        y_velocity = ty - oty
    end
    if not touching and dragging then
        dragging = false
    end
    if not touching and not dragging and math.abs(y_velocity) > 0.1 then
        --y_position = math.min(math.max(y_position + y_velocity, -240), 0)
        y_position = math.min(math.max(y_position + y_velocity, -page1_height + 240), 0)
        y_velocity = y_velocity * friction
    end
    if Controls.check(pad, KEY_DLEFT) and not Controls.check(oldpad, KEY_DLEFT) then
        friction = math.min(friction + .05, .95)
    end
    if Controls.check(pad, KEY_DRIGHT) and not Controls.check(oldpad, KEY_DRIGHT) then
        friction = math.max(friction - .05, .05)
    end
    if Controls.check(pad, KEY_START) then
        Graphics.term()
        System.exit()
    end
    oldpad = pad
    otx, oty = tx, ty

    Graphics.initBlend(BOTTOM_SCREEN)
    Graphics.drawPartialImage(0, 0, 0, math.floor(-y_position + .5), 400, 240, page1)
    Graphics.termBlend()

    Graphics.initBlend(TOP_SCREEN, LEFT_EYE)
    Graphics.drawPartialImage(40 - math.floor(10 * lvl_3d + .5), -math.min(math.max(math.floor(-y_position + .5), 0), 240) + 240, 0, math.max(math.floor(-y_position + .5) - 240, 0), 400, 240, page1)
    Graphics.termBlend()

    Graphics.initBlend(TOP_SCREEN, RIGHT_EYE)
    Graphics.drawPartialImage(40 + math.floor(10 * lvl_3d + .5), -math.min(math.max(math.floor(-y_position + .5), 0), 240) + 240, 0, math.max(math.floor(-y_position + .5) - 240, 0), 400, 240, page1)
    Graphics.termBlend()

    if showdebug then
        drawDebug()
    end
    Screen.flip()
end