cmd = false
part = 0

function nextpart()
    cmd = true
    part = part + 1
end

keyhandlers =
{
   x = nextpart
}

function handlekey(k)
    handler = keyhandlers[k.char]
    if (handler ~= nil) then
        handler()
        return true
    else
        return false
    end
end

finished = false

celestia:registereventhandler("key", handlekey)
obs = celestia:getobserver()
obs:singleview()

days = 1
secs = 1.0 / 86400.0
hours = 1.0 / 24.0

nearlandingtime = celestia:tojulianday(2001, 2, 12, 19, 45, 20)

demoparts = { }
demoparts[0] = function()
    celestia:settime(nearlandingtime - 14*hours)
    local eros = celestia:find("Sol/Eros")
    local near = celestia:find("Sol/NEAR Shoemaker")
    obs:singleview()
    obs:splitview("v", 0.5)

    local o = celestia:getobservers()
    o[1]:follow(near)
    o[1]:gotodistance(near, 0.01, 15)
    o[2]:follow(eros)
    o[2]:gotodistance(eros, 100, 10)
end

demoparts[1] = function()
    obs:singleview()
    local obj = celestia:find("Sol/Saturn")
    obs:goto(obj)
end

-- Main demo loop
repeat

celestia:flash("Part " .. part)

if (demoparts[part] == nil) then
    finished = true
else
    demoparts[part]()

    -- Pause for keyboard input
    repeat
    wait()
    until cmd
    cmd = false
end

until finished

celestia:flash("Demonstration finished")