rl.lua

-- title:  game title
-- author: game developer
-- desc:   short description
-- script: lua
-- input: keyboard

local key_repeat          = true
local key_cooldown        = 0.10
local key_1st_cooldown    = 0.25
local key_timer           = 0
local max_key_timer       = key_1st_cooldown

local k_left  = false     -- key flags
local k_right = false
local k_up    = false
local k_down  = false

local moving_left     = false -- movement flags for no-key-repeat
local moving_right    = false
local moving_up       = false
local moving_down     = false
local moving          = false

local UP, DOWN, LEFT, RIGHT = 58, 59, 60, 61
local SS = 8 -- sprite size
local t_old = 0

local x, y = 8*14, 8*8

function TIC()
    local t_now = time()/1000
    local dt = t_now-t_old
    t_old = t_now

    took_turn, k_left, k_right, k_up, k_down = false, false, false, false, false
    cls(2)

    if key(UP)    then k_up    = true end    -- also works with   "keyp(UP,    0, 0)"
    if key(DOWN)  then k_down  = true end    -- also works with   "keyp(DOWN,  0, 0)"
    if key(LEFT)  then k_left  = true end    -- also works with   "keyp(LEFT,  0, 0)"
    if key(RIGHT) then k_right = true end    -- also works with   "keyp(RIGHT, 0, 0)"

    if key_repeat then move_repeat(dt)
    else               move_once() end

    spr(64, x, y, 14)
    print("Took turn", 8, 8, took_turn and 14 or 7)
end

function move_once()
    if k_left and not moving_left and not k_right then
        took_turn = move( -1, 0 )
        moving_left = true
    elseif not k_left and moving_left then
        moving_left = false
    end

    if k_right and not moving_right and not k_left then
        took_turn = move( 1, 0 )
        moving_right = true
    elseif not k_right and moving_right then
        moving_right = false
    end

    if k_up and not moving_up and not k_down then
        took_turn = move( 0, -1 )
        moving_up = true
    elseif not k_up and moving_up then
        moving_up = false
    end

    if k_down and not moving_down and not k_up then
        took_turn = move( 0, 1 )
        moving_down = true
    elseif not k_down and moving_down then
        moving_down = false
    end
end

function move_repeat(dt)
    -- if already moving since last frame, make the cooldown shorter
    -- else, make it longer for the first key press
    if moving then max_key_timer = key_cooldown
    else           max_key_timer = key_1st_cooldown end

    -- check if any movement key is being pressed
    moving = k_left or k_right or k_up or k_down

    -- if none is pressed, reset the timer so the player is free to move
    if not moving then key_timer = 0 end

    -- if no cooldown and a key was pressed
    if key_timer <= 0 and moving then
        if k_left and not k_right then
            if move(-1,  0) then took_turn = true end end
        if k_right and not k_left then
            if move( 1,  0) then took_turn = true end end
        if k_up and not k_down then
            if move( 0, -1) then took_turn = true end end
        if k_down and not k_up then
            if move( 0,  1) then took_turn = true end end

        if took_turn then
            key_timer = max_key_timer end  -- set the cooldown

    -- else if still cooling down, just reduce timer by dt
    else
        key_timer = key_timer-dt
    end
end

function move(dx, dy)
    -- check against obstacles/mobs if player can_move()
    x = x + dx*SS
    y = y + dy*SS
    return true
end