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Corona SDK

Create an Unblock Puzzle Game - Interface Creation

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In this tutorial series, you'll learn how to create an unblock puzzle game. The objective of the game is to clear the path for the square to get out. Read on!


Step 1: Application Overview

Using pre-created graphics we will code an entertaining game using Lua and the Corona SDK API's.

The player will be able to tap on the screen in order to destroy the big bubbles, you can modify the parameters in the code to customize the game.

Step 2: Target Device

The first thing we have to do is select the platform we want to run our app within, that way we'll be able to choose the size for the images we will use.

The iOS platform has these characteristics:

  • iPad 1/2/Mini: 1024x768px, 132 ppi
  • iPad Retina: 2048x1536, 264 ppi
  • iPhone/iPod Touch: 320x480px, 163 ppi
  • iPhone/iPod Retina: 960x640px, 326 ppi
  • iPhone 5/iPod Touch: 1136x640, 326 ppi

Because Android is an open platform, there are many different devices and resolutions. A few of the more common screen characteristics are:

  • Asus Nexus 7 Tablet: 800x1280px, 216 ppi
  • Motorola Droid X: 854x480px, 228 ppi
  • Samsung Galaxy SIII: 720x1280px, 306 ppi

In this tutorial we'll be focusing on the iOS platform with the graphic design, specifically developing for distribution to an iPhone/iPod touch, but the code presented here should apply to Android development with the Corona SDK as well.


Step 3: Interface

A simple and friendly interface will be used. It will involve multiple shapes, buttons, bitmaps and more.

The interface graphic resources necessary for this tutorial can be found in the attached download.


Step 4: Export Graphics

Depending on the device you have selected, you may need to export the graphics in the recommended ppi. You can do that in your favorite image editor.

<
p>I used the Adjust Size... function in the Preview app on Mac OS X.

Remember to give the images a descriptive name and save them in your project folder.


Step 5: App Configuration

An external file will be used to make the application go fullscreen across devices, the config.lua file. This file shows the original screen size and the method used to scale that content in case the app is run in a different screen resolution.

application =
{
    content =
    {
        width = 320,
        height = 480,
        scale = "letterbox"
    },
}

Step 6: Main.lua

Let's write the application!

Open your prefered Lua editor (any Text Editor will work, but you won't have syntax highlighting) and prepare to write your awesome app. Remember to save the file as main.lua in your project folder.


Step 7: Code Structure

We'll structure our code as if it were a Class. If you know ActionScript or Java, you should find the structure familiar.

Necesary Classes

Variables and Constants

Declare Functions

    contructor (Main function)
	
    class methods (other functions)

call Main function

Step 8: Hide the Status Bar

display.setStatusBar(display.HiddenStatusBar)

This code hides the status bar. The status bar is the bar on top of the device screen that shows the time, signal, and other indicators.


Step 9: Background

A simple graphic is used as the background for the application interface. The next line of code stores it.

-- Graphics

-- [Background]

local bg = display.newImage('bg.png')

Step 10: Title View

This is the Title View, it will be the first interactive screen to appear in our game. These variables store its components:

-- [Title View]

local titleBg
local playBtn
local creditsBtn
local titleView

Step 11: Credits View

This view will show the credits and copyright of the game. These variables will be used to store them:

-- [CreditsView]

local creditsView

Step 12: Game Background

This image will be placed on top of our previous background. This will be the game background.

-- Game Background

local gameBg

Step 13: Blocks

The next variables will store the different blocks in the stage.

-- Blocks

local hblocks
local vblocks
local s

Step 14: Movements TextField

The movement textfield value is handled by this variable.

-- Movements TextField

local movements

Step 15: Alert

This is the alert that will be displayed when you win the game. It will complete the level and end the game.

-- Alert

local alertView

Step 16: Variables

This are the variables we'll use. Read the comments in the code to know more about them.

-- Variables

local lastY --Used to reposition the credits view
local dir --stores the dragging direction

-- Level Table:
-- 1 = vertical block
-- 2 = horizontal block
-- 3 = square

local l1 = {{0, 0, 0, 0, 2, 0},
			{0, 0, 0, 0, 0, 0},
			{0, 0, 0, 3, 0, 1},
			{0, 0, 0, 0, 0, 0},
			{0, 0, 0, 0, 0, 0},
			{0, 0, 0, 0, 0, 0},}

Step 17: Declare Functions

Declare all functions as local at the start.

-- Functions

local Main = {}
local startButtonListeners = {}
local showCredits = {}
local hideCredits = {}
local showGameView = {}
local gameListeners = {}
local dragV = {}
local dragH = {}
local hitTestObjects = {}
local update = {}
local alert = {}

Step 18: Constructor

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

function Main()
	-- code...
end

Step 19: 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 Main()
	titleBg = display.newImage('title.png', 58, 70)
	playBtn = display.newImage('playBtn.png', 138, 252)
	creditsBtn = display.newImage('creditsBtn.png', 122, 312)
	titleView = display.newGroup(titleBg, playBtn, creditsBtn)
	
	startButtonListeners('add')
end

Next Time...

In this part of the series you've learned the interface and the basic setup of the game. In the next and final part of the series, we'll handle the level creation, collision detection, and the final steps to take prior to release like app testing, creating a start screen, adding an icon and, finally, building the app. Read the second installment now!

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