พื่นฐานภาษา Lua และ Corona SDK

1. Variable
j = 10 -- global variable
local i = 1 -- local variable
if i > 20 then
local x -- local to the "then" body
x = 20
print(x + 2)
else
print(x) --> 10 (the global one)
end
print(x) --> 10 (the global one)
Types and Values
print(type("Hello world")) --> string
print(type(10))
--> number
print(type(print))
--> function
print(type(type))
--> function
print(type(true))
--> boolean
print(type(nil))
--> nil
print(type(type(X)))
--> string
Control Structures
- if then else
! - while Loop
- for Loop

2. display.newText()
Creates a text object with its top-left corner at (left, top). The local origin is at the
center of the text; the reference point is initialized to this local origin. By default,
the text color is white (255, 255, 255).
Syntax:
display.newText(string, left, top,
[width, height,] font, size )
local myText = display.newText("Hello World!", 0, 0, native.systemFont, 16)
myText:setTextColor(255, 255, 255)
myText.text = "Hello!"
myText.size = 32
myText.text.x = display.contentCenterX
myText.text.y = display.contentCenterY

3. display.newImage( )
Syntax:
object = display.newImage(filename [,baseDirectory] [,left,top])
Example:
local myImage = display.newImage( "images/rocket2.png")
myImage.x = 150
myImage.y = 250

4. display.newRect()
Syntax:
display.newRect( left, top, width, height )
Example:
local myRectangle = display.newRect(0, 0, 150, 50)
myRectangle.strokeWidth = 3
myRectangle:setFillColor(140, 140, 140)
myRectangle:setStrokeColor(180, 180, 180)

5. display.newCircle()
Syntax:
display.newCircle( xCenter, yCenter, radius )
Example:
local myCircle = display.newCircle( 100, 100, 30 )
myCircle:setFillColor(128,128,128)
myCircle.strokeWidth = 5
myCircle:setStrokeColor(128,0,0) -- red

6. display.newGroup()
Description:
Creates a group in which you can add and remove child display objects. Initially,
there are no children in a group. The local origin is at the parent’s origin; the
reference point is initialized to this local origin.
Syntax:
display.newGroup()
Example:
local group1 = display.newGroup()
local group2 = display.newGroup()
local imgGroup1 = display.newImage("images/group1.png")
group1:insert(imgGroup1);
group1.x = 10
group1.y = 20
--print(group1.width)
local imgGroup2 = display.newImage("images/group2.png")
group2:insert(imgGroup2)
group2.x = 160
group2.y = 20
local rect = display.newRect(0,0, 120, 50)
rect.x = group1.width/2
rect.y = group1.height/2
group1:insert(rect)
local circle = display.newCircle(0,0, 25)
circle.x = group2.width/2
circle.y = group2.height/2
group2:insert(circle)

7. display.newGroup()

8. Basic Touch Handling
object:addEventListener
Syntax:
! object:addEventListener( eventName, listener )
Example:
local circle = display.newCircle(0,0, 25)
circle.x = display.contentCenterX
circle.y = display.contentCenterY
local function myListener( self, event )
if event.phase == "began" then
print( "Listener called with event of type " .. event.name )
elseif event.phase == "moved" then
-- User has moved their finger, while touching
elseif event.phase == "ended" or event.phase == "cancelled" then
-- Touch has ended; user has lifted their finger
end
return true -- IMPORTANT
end
circle:addEventListener( "touch", myListener )

9. timer.performWithDelay()
timer.performWithDelay()
timer.pause
timer.cancel
Description:
Call a specified function after a delay.
Syntax:
timer.performWithDelay( delay, listener [, iterations] )
Example:
local time_txt = display.newText("Time", 0,0,
native.systemFont, 25)
time_txt.x = display.contentCenterX
time_txt.y = display.contentCenterY
local sec = 0
local function listener( event )
sec = sec + 1;
time_txt.text = sec
end
timer.performWithDelay(1000, listener,0 )

10. timer.pause()
Description:
Pauses a timer started with timer.performWithDelay.
Syntax:
! result = timer.pause( timerId )
Example:
local time_txt = display.newText("Time",
0,0,native.systemFont,25)
time_txt.x = display.contentCenterX
time_txt.y = display.contentCenterY
local time1
local sec = 0
local function listener( event )
" sec = sec + 1;
time_txt.text = sec
if sec >= 10 then
"time_txt.text = "pause"
"result = timer.pause( time1 )
"
end
end
time1 = timer.performWithDelay(1000,
listener, 0 )

11. timer.resume()
Description:
Resumes a timer that was paused with timer.pause.
Syntax:
! result = timer.resume( timerId )
Example:
local function listener( event )
" sec = sec + 1;
time_txt.text = sec
if sec > 10 then
"time_txt.text = "pause"
"result = timer.pause(time1) -- Pause
"sec = 0
" time_txt.text = “resume”
"result = timer.resume(time1)
end
end
time1 = timer.performWithDelay(1000, listener, 0 )

12. audio
Description:
Plays audio.
Plays the audio specified by the audio handle on a channel. If a channel is
not explicitly specified, an available channel will be automatically chosen
for you if available.
Syntax:
! audio.play( audioHandle [, { [channel=c] [, loops=l] [,
! ! ! duration=d] [, fadein=f] [, onComplete=o] } ])
Example:
-- audio
local buttonGroup = display.newGroup()
local play = display.newImage("images/play.png")
play.x = buttonGroup.width
local pause = display.newImage("images/pause.png")
pause.x = play.width + 10
local resume = display.newImage("images/resume.png")
resume.x = (pause.x + resume.width) + 10
buttonGroup:insert(play)
buttonGroup:insert(pause)
buttonGroup:insert(resume)
buttonGroup.x = display.contentCenterX - 60
buttonGroup.y = 400
-- load sound
local laserSound = audio.loadSound("sounds/MLJ.mp3")
local laserChanel

13. -- play sound
local function playSound(event)
" laserChanel = audio.play(laserSound,{ channel=1, loops=0,
fadein=5000}) -- play the laser on any available channel
end
play:addEventListener("tap", playSound)
-- pause sound
local function pauseSound(event)
" audio.pause(laserChanel)"
end
pause:addEventListener("tap", pauseSound)
--resume sound
local function resumeSound(event)
" audio.resume(laserChanel)
end
resume:addEventListener("tap", resumeSound)

14. Physics
Overview
Corona makes it very easy to add physics to your games, even if you've never
worked with a physics engine before. While the underlying engine is built around
the well-known Box2D, we've taken a radically different design approach that
eliminates most of the coding that is traditionally required.
Why use Physics?
Say you want your game to have a bouncing ball, Corona's Physics engine makes
this easy. In just a few lines of code you can have a ball bouncing around the
screen!
You can also use Physics for action collisions. Say you want to have your player
walk into a certain area on the screen and have an action take place, you can
easily do this by using Corona's Physics engine and using a sensor Physics body.
local physics = require "physics"
physics.setDrawMode()
Description:
Selects one of three possible rendering modes for the physics engine.
This mode may be changed at any time -- see the "DebugDraw" sample
project for an example of how to toggle it on the fly.
Syntax:
physics.setDrawMode( mode )
Example:
physics.setDrawMode( "debug" ) -- shows collision engine outlines
only
physics.setDrawMode( "hybrid" ) -- overlays collision outlines on
normal Corona objects
physics.setDrawMode( "normal" ) -- the default Corona renderer,
with no collision outlines

15. physics.start()
Description:
This function start the physics simulation and should be called before
any other physics functions.
Syntax:
! physics.start( noSleep )
Example:
local physics = require "physics"
physics.start()
-- step 1 setDrawMode
--physics.setDrawMode( "debug" ) -- shows collision engine
outlines only
--physics.setDrawMode( "hybrid" ) -- overlays collision outlines
on normal Corona objects
--physics.setDrawMode( "normal" ) -- the default Corona renderer,
with no collision outlines
-- step 2 physics.addBody
local ball = display.newCircle(0,0, 25)
ball:setFillColor(252,151,241)
ball.x = display.contentCenterX
ball.y = display.contentCenterY/4
physics.addBody( ball, { density = 1.0, friction = 0.3, bounce =
0.2, radius = 25 } )
local left_wall = display.newRect(0,0,4,display.contentHeight)
left_wall:setFillColor(167,96,20)
physics.addBody( left_wall, "static", { density = 1.0, friction =
0.3, bounce = 0.5} )
local right_wall = display.newRect(0,0,4,display.contentHeight)
right_wall:setFillColor(167,96,20)
right_wall.x = display.contentWidth
physics.addBody( right_wall, "static", { density = 1.0, friction =
0.3, bounce = 0.5} )

16. local foot = display.newRect(0,0,display.contentWidth, 4)
foot:setFillColor(167,96,20)
foot.y = display.contentHeight
--foot.rotation = -2
physics.addBody( foot, "static", { density = 1.0, friction = 0.3,
bounce = 0.5} )

17. Storyboard
Scene Template
Description:
This scene template can be used as a bare-bones scene to be used with the
Storyboard API.
Syntax:
Example: SceneTemplate.lua
storyboard.gotoScene()
Description:
Used to transition to a specific scene (determined by scene's module
name). Internally, this will handle all loading/unloading of the scenes.
Scenes may also be explicitly unloaded/removed by the user.
Syntax:
Format 1:
" storyboard.gotoScene( sceneName [, effect, effectTime] )
Example:
Format 1:
local storyboard = require "storyboard"
storyboard.gotoScene( "scene1", "fade", 500 )

18. Build and deploy to device