As an example of creating custom data structures in Lua, I thought I'd give a little demonstration of a linked lists implementation. Note that this isn't going to be an in-depth tutorial or anything; for the most part I'll just be showing pieces of the code.
Linked lists are wonderful data structures, perfect if you need to efficiently add, remove, and iterate through elements. The one trade off is that you can't find an element by an index.
Read moreThis announcement post is a bit overdue, but, better late than never. A short while ago, I released the first version (0.1) of Ammo, my organisational library for LÖVE. Its current version is 0.1.3. I plan to let the library stay in the 0.x range for a while as it's tested by me and any others who use it.
Along with the core library, there's a number of extensions available. The one I'm most excited about is ammo-debug, a versatile, highly customisable debugging console. It provides stuff like output logging, a command system, info graphs, and even simple live coding support. At present its version is 0.2.
Read moreWhen making a game in LÖVE, you'll probably end up needing to customise the mouse cursor. As I recently had to do just that, I thought I'd make a quick tutorial on it. If you want an example cursor, here's the crosshair I'm using in a game right now.
Now, all of what we need is contained within the love.mouse module. The first step is to hide the mouse with love.mouse.setVisible. You'll probably want to do this in love.load:
If you haven't read the previous parts (one, two and three), then I'd highly recommend doing so. For reference, here's a list of the parts in this series:
Command line arguments are stored in the arg table. For example, if we had the script foo.lua:
If you haven't read part one and two already, I'd highly recommend doing so. For reference, here's a list of the parts in this series:
In part one I stated that Lua has "braces of a sort in the form of keywords like then and do." Much like a language with C-based syntax, these "braces" represent blocks, which are essentially sequences of statements. An example of some blocks in Lua:
If you haven't read part one already, I'd highly recommend doing so. For reference, here's a list of the parts in this series:
Tables are essentially associative arrays which can have keys and values of any type. Tables are incredibly flexible, and are the only data structure in Lua, so knowledge of them is crucial.
Read moreIn this series we'll be taking a look at most everything you should know to program in Lua. The series is targeted at people who already know how to program, and as such I'll aim to be brief in my explanations.
Here's an overview of the four parts the compose the series:
In case you didn't already know, Lua is an interpreted programming language. It's fast, flexible, embeddable, simple, and easy to learn. You can get Lua from its download page.
Read moreWell, I think it's about time I made my Ludum Dare 23 postmortem. First of all, I blame not posting in a long time on my seemingly inherent laziness. Procrastination is an easy trap for me it seems, but that's another topic altogether.
Back on subject, the latest Ludum Dare took place between April 21st and 24th, with the main competition ending on the 23rd. It just so happens that this event was Ludum Dare's 10th anniversary, which is pretty awesome.
Read moreA couple days ago I felt like doing a quick game for a little change from the game I've been working on for the last seven weeks. For some reason, I decided that limiting myself to only one pixel would be a cool idea. So last night, in an hour and a half, using FlashPunk, I put together a Simon Says remake called Pixel Says.
Obviously, the only thing that I wasn't able to do successfully with one pixel is have instructions given inside the game; other than that it was perfectly possible to do.
Read moreIn this post I'll be taking a look at how I programmed aspects of the ship's thruster in my game, Facilitated Escape. I'll most likely be making more posts like this in the future (as in, I intend to make a series of "How It Works" posts).
Initially I had a lot of trouble getting the thruster to look right; you might be able to see some of my troubles in the Ludum Dare time-lapse. The reason for this was that I had programmed the game to move the ship on the y axis instead of moving everything else, as expressed by this code (line 72 of ship.lua)
Read moreIn this tutorial, I'll be taking you through my method of enabling objects to dragged by the mouse (in LÖVE of course). You can view the completed code for this tutorial at gist #1196228.
So, say you have an object with x/y coordinates, width, and height, and you want this object to be draggable by the mouse. For this tutorial, I'm just going to construct a table and put in the global, rect:
function love.load()
rect = {
x = 100,
y = 100,
width = 100,
height = 100,
dragging = { active = false, diffX = 0, diffY = 0 }
}
endThe next thing we need to do is define love.draw to draw the rectangle. (We'll see what rect.dragging is all about soon.)
After my complete failure in the last Ludum Dare, I didn't plan to take part in the next one (the 21st), however I decided to give it another shot. I'd learnt a number of things from my failure last time: go with a concept that's really simple, and use simple art, like pixel art, at least if you're a programmer like me.
I also decided not use my personal framework for LÖVE; the biggest reason I failed last time was that my framework was riddled with bugs. My framework is much more solid now, nevertheless my main reasons for not using it are:
Read moreRecently I experimented with an easy way to make lined shapes glow (using LÖVE of course). There are of course other ways of doing it, and there are many styles of glow that can be used, but this is the one I came up with.
love.graphics.setColor(r, g, b, 15)
for i = 7, 2, -1 do
if i == 2 then
i = 1
love.graphics.setColor(r, g, b, 255)
end
love.graphics.setLineWidth(i)
-- draw lined shape here
endThe shape gets drawn multiple times, each time with a different line width, set by i. In all, six shapes are drawn with the widths 7, 6, 5, 4, 3, 1. For all the lines, except the last, the alpha of the colour (by the way, r, g, and b represent the respective values of whatever colour you might choose) is set to 15. Since the alpha of every overlapping colour is added to each other (by default), for each line the colour will get stronger and stronger, giving the glow effect. The last line is given an alpha of 255, since this is where all the "light" is meant to be coming from.
In this tutorial I'll be covering a very important concept in Lua: metatables. Knowledge of how to use metatables will allow you to be much more powerful in your use of Lua. Every table can have a metatable attached to it. A metatable is a table which, with some certain keys set, can change the behaviour of the table it's attached to. Let's see an example.
t = {} -- our normal table
mt = {} -- our metatable, which contains nothing right now
setmetatable(t, mt) -- sets mt to be t's metatable
getmetatable(t) -- this will return mtAs you can see, getmetatable and setmetatable are the main functions here; I think it's pretty obvious what they do. Of course, in this case we could contract the first three lines into this:
In this post, I'll attempt to give you my personal guide on some good steps to getting started with the Love2D game engine (the proper name is LÖVE, which I'll be using from now on). It's not perfect, of course, but I hope you find it useful. If you have any feedback, I'd love to hear from you in the comments.
I'm guessing you probably already know, but for those who don't, LÖVE is a 2D game engine (or, framework). It's an environment which contains a lot of pre-written code targeted at making games. It interfaces with the Lua programming language to makes things even easier for you.
Read moreWhile inspecting the ASCII table a little while ago, I noticed some interesting patterns in it, which can be used for string manipulation. It's important to understand the ASCII table, because it's the base of most encodings.
Note I'll be using C-like syntax in my examples, but I won't be taking advantage of C's characters, which convert stuff like 'a' into 97 (a's ASCII code).
For those who don't know what much about ASCII codes, I'll give you a quick introduction. ASCII stands for "American Standard Code for Information Interchange", which assigns certain numbers to certain common characters. Since computers can only work with numbers, every letter, or character of any sort, must have a number associated with it. ASCII assigns numbers to 128 different commonly used characters (although many of the non-print characters are no longer used for their original purpose).
Read moreThis morning I released strong 1.0.2, which adds three new methods to the mix: camelize, center, and underscore. center is the complement to ljust and rjust, and the others are from Rails' extensions to Ruby's String class. Take note, they aren't yet documented in the function reference.
Anyway, go and grab 1.0.2 at its repo. Enjoy!
Because there was some interest in a part 3, of this series, I've written it, and in this part we'll cover creating bounds that the camera can't move beyond. Make sure you've read part 1 and part 2 before continuing.
In case you're wondering what I mean by this, I mean restricting the movement of the camera to a "box", as in, having minimum and maximum x/y coordinates for the camera. This comes in handy when you're following players, for example, and you don't want the camera to show any of the stuff beyond the level (usually blackness) when the player comes to an edge. Now of course, movement bounding can get much more complicated than a simple rectangle, you restrict it to certain paths and the like, but we're going to keep it simple here.
Read moreIn this post I'm going to be showing you origins when drawing stuff in Love2D. First of all, what are origins? They specify the offset for the origin of the object's x/y coordinates. In other words, if you specify the x origin to be 20, the object will be drawn 20 pixels to the left, as in x - 20. It's the same for the y origin: if we have a y origin of 20, the object will be drawn 20 pixels up, as in y - 20.
This allows us to do many useful things. First of all, if we have an object with centre based coordinates (like physical bodies), instead of drawing like this:
Read moreFrom April 29 to May 2 Ludum Dare 20 has been going on. For those who don't know, the main competition involves making a game based on a certain theme in a 48 period; tough call. Hundreds of developers have a shot at this every four months, and I thought I'd give it a try. In this post, I'm going to write about my experience in it, and the lessons I learnt. I'll let you know now, however, the end result was me pulling out not long after half-way.
So anyway, I started when the competition was about 6 or 7 hours in. My plan was to use the Love2D engine, along with a personal framework I'd written for it. The theme was "It s Dangerous to go Alone! Take this!" So my first idea was to have sort of dangerous test facility which was pitch black with darkness (making it dangerous to go all alone), and you're given a light or something (the "this") to see your way through. Well that didn't work too well, so I switch the character to a rolling ball, and made "this" the ability to propel yourself in any which way.
Read more