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Corona SDK: Build a Space Shooter - Application Setup


In this tutorial series, we'll use the Corona SDK to build an entertaining Space Shooter Game. Read on!

Step 1: Application Overview

Using pre made graphics we will code an entertaining game using Lua and the Corona SDK API. The user will be able to control a ship sprite and shoot against the enemies.

Step 2: Target Device

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

  • iPad: 1024x768px, 132 ppi
  • iPhone/iPod Touch: 320x480px, 163 ppi
  • iPhone 4: 960x640px, 326 ppi

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

  • Google Nexus One: 480x800px, 254 ppi
  • Motorola Droid X: 854x480px, 228 ppi
  • HTC Evo: 480x800px, 217 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 dark, nice looking interface will be displayed. This involves multiple shapes, buttons, bitmaps, and more. A great sprite library is used in the demo of this tutorial, these are part of theSpriteLib by Flying Yogi.

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.

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: Sound

We'll use Sound Effects to enhance the feeling of the game, you can find the sounds used in this example in using the keywords space, explosion and laser.

Step 6: 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.

Step 7: 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 8: 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.

Step 9: Hide Status Bar

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 10: MovieClip Library

Animated graphics will be used in this game, the Corona movieclip library will make this a lot easier.

Step 11: Import Physics

We'll also use the Physics library to handle collisions. Use this code to import it:

Step 12: Background

A simple black background image is added as the background for the application interface, white dots have been added to represent stars.

Step 13: Title View

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

Step 14: Credits

This view will show the credits, year and copyright of the game, this variable will be used to store it.

Step 15: Ship

The ship sprites will be stored by this variable.

Step 16: Boss

This variable stores the boss movieclip.

Step 17: Score

The score value will be handled by the next variable.

Step 18: Lives

We'll use the same sprite as the ship for the lives, they are stored in the following table.

Step 19: Code Review

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

Next Time...

In this part of the series you've performed the basic setup of the application. Stay tuned for part two where we will handle the logic of the application, buttons, behavior, and more. See you next time!

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