Corona SDK: Create an Alphabet Soup Game – Interaction

This is the second installment in our Corona SDK Alphabet Soup Game tutorial. In today’s tutorial, we’ll add to our interface and start coding the game interaction. Read on!

Step 1: Declare Functions

Declare all functions as local at the start.

local Main = {}
local addTitleView = {}
local startBtnuttonListeners = {}
local showCredits = {}
local hideCredits = {}
local showGameView = {}
local gameListeners = {}
local buildSoup = {}
local startDraw = {}
local hitTestObjects = {}
local detectLetters = {}
local alert = {}

Step 2: Constructor

Next we’ll create the function that will initialize all the game logic:

function Main()
	addTitleView()
end

Step 3: Add Title View

Now we place the TitleView in the stage and call a function that will add the tap listeners to the buttons.

function addTitleView()
	titleBg = display.newImage('titleBg.png')
	title = display.newImage('title.png')
	title.x = display.contentCenterX
	title.y = 120
	startBtn = display.newImage('startBtn.png')
	startBtn.x = display.contentCenterX
	startBtn.y = display.contentCenterY + 20
	aboutBtn = display.newImage('aboutBtn.png')
	aboutBtn.x = display.contentCenterX
	aboutBtn.y = display.contentCenterY + 65
	titleView = display.newGroup()
	titleView:insert(titleBg)
	titleView:insert(title)
	titleView:insert(startBtn)
	titleView:insert(aboutBtn)
	startButtonListeners('add')
end
end

Step 4: Start Button Listeners

This function adds the necesary listeners to the TitleView buttons.

function startButtonListeners(action)
	if(action == 'add') then
		aboutBtn:addEventListener('tap', showCredits)
		startBtn:addEventListener('tap', showGameView)
	else
		aboutBtn:removeEventListener('tap', showCredits)
		startBtn:removeEventListener('tap', showGameView)
	end
end

Step 5: Show Credits

The credits screen is shown when the user taps the about button, a tap listener is added to the credits view to remove it.

function showCredits:tap()
	aboutBtn.isVisible = false
	startBtn.isVisible = false
	about = display.newImage('about.png')
	about.x = about.width * 0.474
	about.y = display.contentHeight + about.height
	transition.to(about, {time = 300, y = display.contentHeight - about.height/2.4, onComplete = function() about:addEventListener('tap', hideCredits) end})
end

Step 6: Hide Credits

When the credits screen is tapped, it’ll be tweened out of the stage and removed.

function hideCredits()
	transition.to(about, {time = 300, y = display.contentHeight+about.height, onComplete = function() aboutBtn.isVisible = true startBtn.isVisible = true about:removeEventListener('tap', hideCredits) display.remove(about) about = nil end})
end

Step 7: Show Game View

When the Start button is tapped, the title view is tweened and removed revealing the game view.

function showGameView:tap()
	transition.to(titleView, {time = 300, y = -titleView.height, onComplete = function() display.remove(titleView) titleView = nil buildSoup() gameListeners('add') end})
end

Step 8: Game Listeners

This code adds tap listeners to the game background, and these will be used to draw the selection line and identify the selected letters.

function gameListeners(action)
	if(action == 'add') then
		gameBg:addEventListener('touch', startDraw)
		gameBg:addEventListener('touch', detectLetters)
	else
		gameBg:removeEventListener('touch', startDraw)
		gameBg:removeEventListener('touch', detectLetters)
	end
end

Step 9: Build Soup Function

One of the main functions of the game; this will browse the Map table to create all the textfields and place them in the stage, continue to the next step to see its behavior.

function buildSoup()
	-- Code...
end

Step 10: Create Character TextFields

A double for is used to identify the elements in the Map table, one for the horizontal values and one for the vertical. The code will create a textfield for every value found in the table and then place them in the stage.

for i = 1, 10 do
		for j = 1, 12 do
			local tf = display.newText('', 0, 0, 'Arial', 19)
			tf:setTextColor(102, 102, 102)
			tf.width = 22
			tf.height = 21
			tf.x = math.floor(-10 + (31.3 * i))
			tf.y = math.floor(-10 + (35 * j))

Step 11: Display Random Letters

The chosen words are already in the table, and the rest of the values are filled by 0′s at the moment. The following lines change those 0′s to a random letter.

-- Change 0's to Random Letters
			if(L1Map[j][i] == 0) then
				L1Map[j][i] = alphabet[math.floor(math.random() * table.maxn(alphabet))+1]
			end
			tf.text = L1Map[j][i]
			tfs:insert(tf)
		end
	end

Step 12: Add Words List

This code creates two textfields that will contain the list of values to find and the values already found.

-- Add Words List
	local wordsString = ''
	for i = 1, #L1 do
		wordsString = wordsString .. ' ' .. L1[i]
	end
	wordsList = display.newText(wordsString, 5, 430, 'Arial', 14)
	wordsList:setTextColor(238, 238, 238)
	currentWords = display.newText('', 5, 455, 'Arial', 14)
	currentWords:setTextColor(238, 146, 63)

Step 13: Draw Selection Line

A semi transparent line will be used to highlight the letters in the stage, in the next function this line is created and added to the stage.

function startDraw:touch(e)
	if(e.phase == 'began') then
		initX = e.x
		initY = e.y
	elseif(e.phase == 'ended') then
		line = display.newLine(initX, initY, e.x, e.y)
		line.width = 16
		line:setColor(255, 142, 42, 60)
		lines:insert(line)
	end
end

Step 14: Code Review

Here is the full code written in this tutorial alongside comments to help you identify each part:

-- Alphabet Soup Game
-- Developed by Carlos Yanez
-- Hide Status Bar
display.setStatusBar(display.HiddenStatusBar)
-- Graphics
-- [Background]
-- [Game Background]
local gameBg = display.newImage('bg.png')
-- [Title View]
local titleBg
local title
local startBtn
local aboutBtn
-- [TitleView Group]
local titleView
-- [CreditsView]
local about
-- [Words List Textfield]
local wordsList
local currentWords
-- [Letter Texfields Container]
local tfs = display.newGroup()
-- [Selection Line]
local line
local lines = display.newGroup()
-- [Alert]
local alert
-- [Sound]
local bell = audio.loadStream('bell.caf')
-- Variables
local L1 = {'IPHONE', 'ANDROID', 'CORONA', 'MOBILE', 'GAMES'}
local L1Map = {{0, 0, 'I', 0, 0, 0, 'G', 0, 0, 0},
               {0, 0, 'P', 0, 0, 0, 'A', 0, 0, 0},
               {0, 0, 'H', 0, 0, 0, 'M', 0, 0, 0},
               {0, 'M', 'O', 'B', 'I', 'L', 'E', 0, 0, 0},
               {0, 0, 'N', 0, 0, 0, 'S', 0, 0, 0},
               {0, 0, 'E', 0, 0, 0, 0, 0, 0, 0},
               {'C', 'O', 'R', 'O', 'N', 'A', 0, 0, 0, 0},
               {0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
               {0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
               {0, 0, 'A', 'N', 'D', 'R', 'O', 'I', 'D', 0},
               {0, 0, 0, 0, 0, 0, 0, 0, 0, 0},
               {0, 0, 0, 0, 0, 0, 0, 0, 0, 0}}
local alphabet = {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z'}
local correct = 0
-- Functions
local Main = {}
local addTitleView = {}
local startBtnuttonListeners = {}
local showCredits = {}
local hideCredits = {}
local showGameView = {}
local gameListeners = {}
local buildSoup = {}
local startDraw = {}
local hitTestObjects = {}
local detectLetters = {}
local alert = {}
function Main()
	addTitleView()
end
function addTitleView()
	titleBg = display.newImage('titleBg.png')
	title = display.newImage('title.png')
	title.x = display.contentCenterX
	title.y = 120
	startBtn = display.newImage('startBtn.png')
	startBtn.x = display.contentCenterX
	startBtn.y = display.contentCenterY + 20
	--startBtn.name = 'startBtn'
	aboutBtn = display.newImage('aboutBtn.png')
	aboutBtn.x = display.contentCenterX
	aboutBtn.y = display.contentCenterY + 65
	--aboutBtn.name = 'aboutBtn'
	titleView = display.newGroup()
	titleView:insert(titleBg)
	titleView:insert(title)
	titleView:insert(startBtn)
	titleView:insert(aboutBtn)
	startButtonListeners('add')
end
function startButtonListeners(action)
	if(action == 'add') then
		aboutBtn:addEventListener('tap', showCredits)
		startBtn:addEventListener('tap', showGameView)
	else
		aboutBtn:removeEventListener('tap', showCredits)
		startBtn:removeEventListener('tap', showGameView)
	end
end
function showCredits:tap()
	aboutBtn.isVisible = false
	startBtn.isVisible = false
	about = display.newImage('about.png')
	about.x = about.width * 0.474
	about.y = display.contentHeight + about.height
	transition.to(about, {time = 300, y = display.contentHeight - about.height/2.4, onComplete = function() about:addEventListener('tap', hideCredits) end})
end
function hideCredits()
	transition.to(about, {time = 300, y = display.contentHeight+about.height, onComplete = function() aboutBtn.isVisible = true startBtn.isVisible = true about:removeEventListener('tap', hideCredits) display.remove(about) about = nil end})
end
function showGameView:tap()
	transition.to(titleView, {time = 300, y = -titleView.height, onComplete = function() display.remove(titleView) titleView = nil buildSoup() gameListeners('add') end})
end
function gameListeners(action)
	if(action == 'add') then
		gameBg:addEventListener('touch', startDraw)
		gameBg:addEventListener('touch', detectLetters)
	else
		gameBg:removeEventListener('touch', startDraw)
		gameBg:removeEventListener('touch', detectLetters)
	end
end
function buildSoup()
	for i = 1, 10 do
		for j = 1, 12 do
			local tf = display.newText('', 0, 0, 'Arial', 19)
			tf:setTextColor(102, 102, 102)
			tf.width = 22
			tf.height = 21
			tf.x = math.floor(-10 + (31.3 * i))
			tf.y = math.floor(-10 + (35 * j))
			-- Change 0's to Random Letters
			if(L1Map[j][i] == 0) then
				L1Map[j][i] = alphabet[math.floor(math.random() * table.maxn(alphabet))+1]
			end
			tf.text = L1Map[j][i]
			tfs:insert(tf)
		end
	end
	-- Add Words List
	local wordsString = ''
	for i = 1, #L1 do
		wordsString = wordsString .. ' ' .. L1[i]
	end
	wordsList = display.newText(wordsString, 5, 430, 'Arial', 14)
	wordsList:setTextColor(238, 238, 238)
	currentWords = display.newText('', 5, 455, 'Arial', 14)
	currentWords:setTextColor(238, 146, 63)
end
function startDraw:touch(e)
	if(e.phase == 'began') then
		initX = e.x
		initY = e.y
	elseif(e.phase == 'ended') then
		line = display.newLine(initX, initY, e.x, e.y)
		line.width = 16
		line:setColor(255, 142, 42, 60)
		lines:insert(line)
	end
end

Next Time…

In the next and final part of the series, we’ll handle the letter identification, display the words already found, and the final steps to take prior to release like app testing, creating a start screen, adding an icon and, finally, building the app. Stay tuned for the final part!