Max GlenisterA menu and state system
I’ve been playing with state systems lately, and decided to build a menu system to play with going between each state.
First of all, my helper functions… I’m using this to print outlined text:
-- print text with an outline
function printo(str,x,y,c1,c2)
for xoff=-1,1 do
for yoff=-1,1 do
print(str,x+xoff,y+yoff,c1)
end
end
print(str,x,y,c2)
end
The menu function has two modes, one for running in _update() and one for running in _draw(), you control this by passing "u" or "d" as the second argument.
The first agument takes a table containing a menu definition. I’ll talk more about this with an example after the wall of code:
function menu(m, mode)
local ic=#m.items
if mode == "u" then
if btnp(2) then
-- up
m.selection -= 1
if m.selection < 1 then
m.selection = 1
end
end
if btnp(3) then
-- down
m.selection += 1
if m.selection > ic then
m.selection = ic
end
end
if btnp(5) then
-- x
if m.items[m.selection][2] then
m.items[m.selection][2]()
end
end
end
if mode == "d" then
local padding={4,4,0,6}-- t/r/b/l
local lineheight=8
-- find longest string
local widest_str=0
for i,item in pairs(m.items) do
if #item[1] > widest_str then
widest_str = #item[1]
end
end
local width = (widest_str*4)+padding[2]+padding[4]
local height = (ic*lineheight)+padding[1]+padding[3]
local xoff = 64 - (width/2)
local yoff = 64 - (height/2)
local x0 = xoff
local y0 = yoff
local x1 = xoff + width
local y1 = yoff + height
-- box
rect(x0-2,y0+1,x1+2,y1+2, 5)
rect(x0-1,y0-1,x1+1,y1+1,0)
rectfill(x0,y0,x1,y1,1)
rect(x0,y0,x1,y1,7)
-- aditional text
if m.guide then
local _w = #m.guide*4
local _x = 64 - (_w/2)
local _y = y1+padding[1]+2
printo(m.guide,_x,_y, 0, 7)
end
-- items
for i,item in pairs(m.items) do
if i == m.selection then
-- selection highlight
printo(
item[1],
xoff+padding[4],
yoff+padding[1]+((i-1)*lineheight),
0,7
)
if m.items[m.selection][2] then
palt(0,false)
palt(1,true)
local xadj=(5 - time()%3)
spr(1,x0-xadj,y0+padding[1]+((i-1)*lineheight) - 1)
pal()
end
else
-- normal item
printo(
item[1],
xoff+padding[4],
yoff+padding[1]+((i-1)*lineheight),
0,6
)
end
end
end
end
There’s a lot going on there, but it’s basically maintain a counter for the user’s current selection, and then if there is a function associated with a menu item call it when the x button is pressed.
Here’s how the menu definitions look
_menu_start = {
selection = 1,
items = {
{"new game", game},
{"new game", game},
{"new game", game},
{"new game", game},
{"credits", credits}
},
guide="❎ to select"
}
_menu_game = {
selection = 1,
items = {
{"game over", die},
{"congratulations", win},
{"---"},
{"back", start}
}
}
_menu_credits = {
selection = 1,
items = {
{"this sub menu contains lots of"},
{"strings without actions bound "},
{"to them, so you can just show "},
{"multiple lines of text."},
{"30 characters is a rough limit"},
{"---"},
{"back", start}
},
guide="enjoy ♥"
}
You can go between menus using a state system. Here’s the barebones of a state system. We assign a new function to _upd() and _drw() each time the state changes.
function _init()
start() -- defined later
end
--update
function _update()
_upd()
end
function update_start()
menu(_menu_start, "u")
end
function update_game()
menu(_menu_game, "u")
end
function update_credits()
menu(_menu_credits, "u")
end
--draw
function _draw()
cls(13)
_drw()
end
function draw_start()
menu(_menu_start, "d")
end
function draw_game()
menu(_menu_game, "d")
end
function draw_credits()
menu(_menu_credits, "d")
end
-- functions that are called directly
-- through menu selections
function start()
_upd=update_start
_drw=draw_start
end
function game()
_upd=update_game
_drw=draw_game
end
function credits()
_upd=update_credits
_drw=draw_credits
end
And here’s how it looks in action. I’ve got a custom sprite for the selection hand drawn in sprite slot 1:
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