How Codea Works¶
Codea is primarily designed as a realtime graphical engine that uses callbacks to draw and update the screen
When you create a project you are given a basic template in Main.lua that
contains some global functions:
-- Called once at the beggining
function setup()
x = WIDTH/2
y = HEIGHT/2
end
-- Called every frame
function draw()
background(128)
style.push().fill(color.red).stroke(255).strokeWidth(5)
ellipse(x, y, 100, 100)
end
-- Called when a touch is detected or updated
function touched(touch)
if touch.began or touch.moving then
x = touch.x
y = touch.y
end
end
Each of these functions are called by Codea in response to specific events, such as
setup() being called when the project begins running, while draw() is called
every time the screen is about to be redrawn
The touched(touch) callback is called in reponse to the screen being touched
(on iOS) or a mouse press (on MacOS)
setup()¶
This function is called exactly once, right before the first frame is about to be drawn and is an ideal spot to put your initialisation code, setting everything up for when draw() will be called!
draw()¶
This is the meat and potatoes of any Codea app, where you will do the majority of your update and drawing logic
touched(touch)¶
This is your primary source of interaction with users
Additional Events¶
update(dt)¶
As an alternative to doing your update logic in draw() you can also use update(dt), where dt is the amount of delta time since last frame (also available in time.delta)
fixedUpdate(dt)¶
A special update function that is called a fixed number of times per second regardless of the current framerate, ideal for physics calculations and simulations that require a stable stepping rate. The delta time value passed in is the same as time.fixedDelta