Hello,
I’ve got two questions about Codea.
First, how exactly does Multitouch work? I know that this has already been asked several times on the forums but I still don’t get it. How can I create arrows or a virtual joystick for movement and, for example, a jump button that can be touched at the same time?
Is there a way to implement a 2D camera that doesn’t only scroll like in a platform but can zoom in or out like
in some strategy games?
Thanks in advance for any help! 
@Leon For multitouch, you will need to use the Touch ID. Each touch creates a unique id number that can be used to determine which touch is doing something. As for zooming in or out, that can also be done. If you’re using sprites, just modify the width and height parameters to increase or decrease the Sprite size to make it look like you’re zooming in or out.
The code for the mutlitouch example:
--# Main
function setup()
print("This example tracks multiple touches and colors them based on their ID")
-- keep track of our touches in this table
touches = {}
end
-- This function gets called whenever a touch
-- begins or changes state
function touched(touch)
if touch.state == ENDED then
-- When any touch ends, remove it from
-- our table
touches[touch.id] = nil
else
-- If the touch is in any other state
-- (such as BEGAN) we add it to our
-- table
touches[touch.id] = touch
end
end
function draw()
background(0, 0, 0, 255)
for k,touch in pairs(touches) do
-- Use the touch id as the random seed
math.randomseed(touch.id)
-- This ensures the same fill color is used for the same id
fill(math.random(255),math.random(255),math.random(255))
-- Draw ellipse at touch position
ellipse(touch.x, touch.y, 100)
end
end
the local variable touch in the touched function:
To understand multitouch, you must first understand what the variable touch (or whatever you named it) is. It stores information such as the x and y position, the speed the touch is moving, and more, but the most important thing to understand for multitouch is that each touch has a unique ID. You can access the id of a touch with touch.id.
in setup:
in touched
touches at the index of the touch ID.in draw
math.random to whatever the id of the touch it is currently at is.I hoped that helped. I tried to be as clear as possible.
Thanks
As far as zooming is concerned I thought of an alternative to this. But if this is how I am supposed to do, it I’ll stick with it.
Thanks Kolosso for your detailed example! How would I transfer this to buttons? 
@Leon If you have an alternative to zooming and it works better, then use it. I don’t know if there’s a best way, it all depends on what and how you’re displaying something.
@Leon Here’s an example I already had that allows the shoot and direction buttons to be pressed at the same time. Not sure if you can use this, but it might give you an idea.
function setup()
rectMode(CENTER)
dir=""
stab=""
btn={}
table.insert(btn,buttons(300,300,100,50,"UP"))
table.insert(btn,buttons(300,100,100,50,"DOWN"))
table.insert(btn,buttons(200,200,100,50,"LEFT"))
table.insert(btn,buttons(400,200,100,50,"RIGHT"))
table.insert(btn,buttons(300,400,100,50,"SHOOT"))
end
function draw()
background(40, 40, 50)
for a,b in pairs(btn) do
b:draw()
if b.pressed then
if b.text=="SHOOT" then
stab=b.text
elseif dir=="" then
dir=b.text
end
end
end
fill(255)
text(dir,WIDTH/2,HEIGHT-50)
text(stab,WIDTH/2,HEIGHT-100)
end
function touched(t)
for a,b in pairs(btn) do
b:touched(t)
end
end
buttons=class()
function buttons:init(x,y,w,h,txt)
self.x=x
self.y=y
self.w=w
self.h=h
self.text=txt
self.left=x-w/2
self.right=x+w/2
self.bottom=y-h/2
self.top=y+h/2
self.pressed=false
self.id=0
end
function buttons:draw()
fill(255)
if self.pressed then
fill(255, 158, 0, 255)
end
rect(self.x,self.y,self.w,self.h)
fill(255,0,0)
text(self.text,self.x,self.y)
end
function buttons:touched(t)
if t.state==BEGAN or t.state==MOVING and self.id==0 then
if t.x>self.left and t.x<self.right and
t.y>self.bottom and t.y<self.top then
self.pressed=true
self.id=t.id
end
end
if t.state==MOVING and self.id==t.id then
if t.x>self.left and t.x<self.right and
t.y>self.bottom and t.y<self.top then
self.pressed=true
else
self.pressed=false
self.id=0
dir=""
stab=""
end
end
if t.state==ENDED and self.id==t.id then
self.pressed=false
self.id=0
dir=""
stab=""
end
end
You can also use the scale command to zoom
@Leon I made a two player tank game a few months ago. It has pretty good joystick controls, if you want to look at another example
https://gist.github.com/Dwiniflin/10c4a478e43b6d1532499df9439d9627
i have written a simplified multitouch handler. basically you copy the fallowing code into your game (in a separate tab) and it overrides codea’s default ?touched? method. you can then retrieve all touches from your current multitouch gesture/session like so:
?function touched(touch1, touch2, …)? or as a table ?function touched(…) touches={…}?
local touches = {}
local expiredTouches = 0
local gestureCountdown = .08 -- ADJUST!
local touchesAutoDispatcher
local dispatchTouches = touched
function touched(touch)
-- Identify touch
local gesture, uid = #touches > 0 and touches[1].initTime + gestureCountdown < ElapsedTime
for r, t in ipairs(touches) do
if touch.id == t.id then uid = r end
touches[r].state = "RESTING"
end
-- Cache updates
local rt = touches[uid] or {}
local template = {
id = rt.id or touch.id,
state = touch.state,
tapCount = CurrentTouch.tapCount,
initTime = rt.initTime or ElapsedTime,
duration = ElapsedTime - (rt.initTime or ElapsedTime),
initX = rt.initX or touch.x,
initY = rt.initY or touch.y,
x = touch.x,
y = touch.y,
prevX = touch.prevX,
prevY = touch.prevY,
deltaX = touch.deltaX,
deltaY = touch.deltaY,
radius = touch.radius,
radiusTolerance = touch.radiusTolerance,
force = remapRange(touch.radius, 0, touch.radius + touch.radiusTolerance, 0, 1)
}
if uid then
-- Update touches
touches[uid] = template
-- Dispatch touches
if touch.state == ENDED then
-- First touch expired while gesture still active (or waiting to get active)
if expiredTouches == 0 then
-- Gesture was waiting to get active
if touchesAutoDispatcher then
-- Sync all touch states to BEGAN
-- Still dispatch the planed BEGAN state from Auto-Dispatch
for r, t in ipairs(touches) do
touches[r].state = BEGAN
touches[r].initX = t.x
touches[r].initY = t.y
end
dispatchTouches(table.unpack(touches))
-- Cancel gesture!
tween.reset(touchesAutoDispatcher)
touchesAutoDispatcher = nil
end
-- Sync all touch states to ENDED
for r, t in ipairs(touches) do
touches[r].state = ENDED
end
-- Dispatch ENDED
dispatchTouches(table.unpack(touches))
end
-- Delete all touches when all expired
expiredTouches = expiredTouches + 1
if expiredTouches == #touches then
touches = {}
expiredTouches = 0
end
else
-- Dispatch MOVING
if not touchesAutoDispatcher and gesture and expiredTouches == 0 then
dispatchTouches(table.unpack(touches))
end
end
else
-- Register touch
-- Ignore new touches when gesture already active
if not gesture and touch.state == BEGAN then
table.insert(touches, template)
uid = #touches
-- Auto-Dispatch touches
if uid == 1 then
-- Dispatch BEGAN ... when gesture gets active
touchesAutoDispatcher = tween.delay(gestureCountdown, function()
-- Sync all touch states to BEGAN
for r, t in ipairs(touches) do
touches[r].state = BEGAN
touches[r].initX = t.x
touches[r].initY = t.y
end
-- Dispatch BEGAN
dispatchTouches(table.unpack(touches))
touchesAutoDispatcher = nil
end)
end
end
end
end