-- set the width of the horizontal progress bar
local function update_horizontal(p)
    local node = gui.get_node("horizontal")
    local size = gui.get_size(node)
    size.x = p * 400 -- max width is 400 pixel
    gui.set_size(node, size)
end

-- set value of numeric progress indicator (in percent from 0% to 100%)
local function update_numeric(p)
    local node = gui.get_node("numeric")
    local percent = math.floor(p * 100)
    gui.set_text(node, tostring(percent) .. "%")
end

-- update radial/circle progress by changing the fill angle
local function update_radial(p)
    local node = gui.get_node("radial")
    local angle = p * 360 -- full circle is 360 degrees
    gui.set_fill_angle(node, angle)
end

function init(self)
    self.time = 0
end

function update(self, dt)
    self.time = self.time + dt

    -- calculate a value between 0.0 and 1.0
    -- the value will gradually increas from 0 to 1 during 3 seconds
    local p = (self.time % 3) / 3
    update_numeric(p)
    update_horizontal(p)
    update_radial(p)
end