local sGameRunning
local sMoving
local sStartTime
local sDirection

on preOpenCard
    set the layerMode of btn "road1" to "dynamic"
    set the layerMode of btn "road2" to "dynamic"
    set the layerMode of btn "car" to "dynamic"

    setupscreen
end preOpenCard

on setupscreen
    set the bottomLeft of btn "road1" to 0, the height of this stack
    set the bottomLeft of btn "road2" to the right of btn "road1", the height of this stack
    set the left of btn "car" to 10
    set the bottom of btn "car" to the height of this stack - 30
end setupscreen

on startLoop
    ## Checks to see if the loop is already running; if not start loop
    if sMoving is not true then
        ## Starts responding to the game loop and resets script locals
        put true into sMoving
        put the millisecs into sStartTime
    end if
end startLoop

on stopLoop
    ## Stop responding to the game loop
    put false into sMoving
end stopLoop

on mouseDown
    put the millisecs into sStartTime
end mouseDown

on mouseUp
    put the millisecs into sStartTime
end mouseUp

on updateScreen
    ## Check if the screen should be updated
    if sMoving is true then
        moveRoad
        carAccelerate
    else # (if sMoving is false)
        
    end if
end updateScreen

on moveRoad
    set the left of btn "road1" to the left of btn "road1" - 5
    set the left of btn "road2" to the left of btn "road2" - 5
    if the right of btn "road2" < 0 then
        set the bottomleft of btn "road2" to the bottomright of btn "road1"
    end if
    if the right of btn "road1" < 0 then
        set the bottomleft of btn "road1" to the bottomright of btn "road2"
    end if
end moveRoad

on carAccelerate
    put the millisecs - sStartTime into tTimeSinceChange
    put 9.81 * ((tTimeSinceChange / 1000)^2) into tMoveAmount ## roughly simulate gravity, assuming one pixel is equal to one metre
    
    ## Update the game state
    if the mouse is not down then
        ## If the mouse is not being pressed, the car should slow down
        set the icon of button "car" to 1020 # you may need to change this image id number
        if (the left of button "car" - tMoveAmount) > the left of this card then
            set the right of button "car" to the right of button "car" - tMoveAmount
        end if
    else
        ## otherwise the car should accelerate
        set the icon of button "car" to 1020 # you may need to change this image id number
        if (the right of button "car" + tMoveAmount) <= the right of this card then
            set the right of button "car" to the right of button "car" + tMoveAmount
        end if
    end if
end carAccelerate