L÷VE for Lua Game Programming

Before we build our game, we need a copy of LÖVE's engine running on our computer; a copy of the framework installed will help the computer to interpret the code we will be writing.

Direct your web browser to www.love2d.org, scroll to the download section of the site and choose the installer that is compatible with your computer.

It is advisable that we download an installer instead of the source codes, except for when we want to be geeky and build it ourselves.

When you are through with downloading the installer, run the setup and follow the instructions.

When your installation is complete, run the program; you should see a the window displaying a beautiful animation on the screen.

Linux users are required to download the .deb install file by clicking on build number of their operating system; users running Precise Pangolin Ubuntu OS should click on the 12.04 link. Run the install program and follow the instructions. If the LÖVE framework is fully installed, you can double-click on a .love file to run it.

Mac users should visit the LÖVE wiki (https://www.love2d.org/wiki/Getting_Started) page for instructions on how to install LÖVE and run a packaged game.

Running a LÖVE game

First of all, we assume we do not have any LÖVE game yet. OK, then let's just write a simple "Hello World!" program and run it with LÖVE. Open up a text editor and write the following Lua code:

--create a display

function love.draw()
--display a text on a 800 by 600 screen in the positions x= 400, and --y=300
   love.graphics.print('hello world!', 400, 300)

end

Now save this code as main.lua. Open a folder for your game project, put your main.lua file inside the folder, and compress the content of the folder. Change the .zip extension to .love. You'll notice a change in the icon of the compressed file; it changes to a LÖVE logo. Now that we've done all that, we can run our game. If you follow the instructions correctly, you should see a screen similar to the following screenshot:

If you do not compress the file properly, you will get the following blue screen displaying error information:

Note that it is the content of your game folder that should be compressed and not the folder itself, and make sure the main.lua file is at the top level.

Basic structure of LÖVE

There are three basic functions that make up a LÖVE game that are essential in most of the games you will be designing with LÖVE. For now, the following are the basics to make a small game:

• love.load(): This preloads all the necessary assets we need to make our game.

• love.update(dt): This is where we do most of our maths, where we deal with events; it is called before a frame is drawn. dt is the time it takes to draw a frame (in seconds).

• love.draw(): This draws all that we want to display on the screen.

Examples

The basic structure of the game is done as you can see in the following code:

--load our assets
function love.load()
   --load all assets here
end




--update event
function love.update(dt)
--do the maths
end


--draw display
function love.draw()
--describe how you want/what to draw.
end

That's just it, well... maybe! So let's play with these chunks one more time.

Now let's edit main.lua to enable loading sample assets that we want to use within the game:

function love.load()

   local myfont = love.graphics.newFont(45)

   love.graphics.setFont(myfont)

   love.graphics.setColor(0,0,0,225)

   love.graphics.setBackgroundColor(255,153,0)
end


function love.update()



end

function love.draw()

   love.graphics.print('Hello World!', 200, 200)

end

Conf.lua

Before you go on and start coding your game, you need to give your video game some specs such as window width, window height, and window title. So set up a new file named conf.lua; inside it you can then create your game specs as shown in the following code snippet:

function love.conf(w)

w.screen.width = 1024 

w.screen.height = 768

w.screen.title = "Goofy's Adventure"

end

You can manipulate the figures and titles any way and also change that w to whatever variable you want.

The preceding code does the following:

• Loads our font

• Sets the font color

• Sets the background color

• Draws text on the screen

• Configures the screen size

Basically we are using the love.graphics module; it can be used to draw (in the real sense) texts, images, and any drawable object in the scene. In the previous code snippets, we defined our fonts with the love.graphics.newFont(45) that formats our text by declaring the size of the font as 45. setFont() loads the font we defined as myfont, setColor() colors the text in the RGB format, and setBackgroundColor() sets the background.

Then we printed text using the love.graphics.print('text', x, y) function in the draw function with three parameters parsed in it: the text and the x and y coordinates. We are not going to do anything in the love.update() function yet, because we are not dealing with scene events.

So let's load our game as a .love file and see what it displays:

Now we can grab a mug of cappuccino with Ray-Bans on and smile; we have installed the LÖVE game engine, text editor, and Visual tile-level editor (Tiled). We have also got a quick look at the basic structure for writing our game in Lua and displayed "Hello World!" in a colored background window. Next we'll go through how to draw 2D objects, move objects, and animate character sprites.