Over the last semester, I've been working on a game engine. It was meant to be a personal challenge for myself, to see if I could make my own game engine with some bare materials. Those being C++, OpenGL, and Qt. I wanted it to be more though. Seeing as most professional game engines these days (developed by community or company) feature some sort of scripting engine, I decided to make my own scriptable game engine.
After some troubles with trying to embed Python & Lua inside of a C++ dummy projects, I discovered this thing called ChaiScript. The tl;dr is that it's a scripting language for C++ that's dead simple to use. I decided to use it for my project since it gave me a no hassle way to add scripting features to my project. It was dead simple as "include the headers," and "give me a pointer to your C++ function/variable, and tell me what you want to call it."
Of course with simplicity, comes some cost. One of the first things for example are the long build times. If you statically include ChaiScript (which is the simplest way of using it), expect to take a small break when compiling. This can be easily remedied by dynamically linking ChaiScript's standard library and including a .dll/.so file alongside your executable. I did this when developing Masala.
I also ran into performance issues with ChaiScript. At the current version (5.8.1), the language is executed using an Abstract Syntax Tree. While this is necessary for parsing a language, using it to run code is much slower than it could be.
Enough about ChaiScript, let's talk about the engine itself, Masala!
Masala was built using C++ (14), Qt 5.x, ChaiScript, and OpenGL. I had the goal of trying to create a reusable game engine where you write all of your logic inside of ChaiScript files. It follows a very lose XNA/MonoGame-like pattern. Right now it features:
- Cross platform (Built with Linux)
- Featureful sprite object (with animations!)
- Tilemaps (Flare maps)
- Basic sound effects
- Keyboard Input
- Interactive debugging terminal
It's pretty simple. I mean, very simple. I don't think it stands up well to other engines that are out there, so I really consider it to be an experiment in using ChaiScript for a game engine.
I implemented two simple games, one being a clone of the classic Atari Pong:
And another more original one I've dubbed "Grab n' Dodge:"
I would say that I accomplished my goal in writing a game engine. Something that I have never done. As for the cross-platform part, I was able to get the code to compile on OS X and Windows, but had some trouble upon running it. One of my friends said that he was able to get it working on OS X, but I haven't seen the proof.
If anyone wants to help me getting this running on Windows or OS X, contact me. Since it was made using cross platform tools, it should work on all of the OSes Qt & OpenGL support.
And last, you can find the official code repository over here on GitLab. It's GPLv3 licensed.
Back around mid to late July in 2014 I set out to create Blit. One year on now (as of last Wednesday), I've made a lot of progress from practically nothing. Thinking back I ask myself “why did I want to make Blit?”
I've made many other projects before. Some of them successes whereas others were really failures (cough buzz cough). Those projects had something in common. They were short, small, and contained. When I look back on all of the stuff that I've made, I noticed that there was nothing that I could call a “grand,” or “large,” project. I wanted something that I could call a major project that I built. More importantly I wanted to know how to manage a larger project; something I've never done before.
So I set a goal for myself: “Make something large. Something that you can never really call 'complete,' but work on it for an entire year.” That's what I did. I had nothing more than a silly GitHub streak to motivate me. It now says “371 days.” There were a few days where all I did was just update a TODO file, add some extra documentation, or ones that I didn't want to work on it at all (but I did anyways).
Blit still isn't really what I originally imaged it to be. Some sort of 2D Animation solution for pixel art and larger things (and hopefully pencil testing too). And I'm still not sure 100% what I want out of it. I consider what I've done so far to be nothing more than a prototype for a future vision.
I've met my goal of “work on something for a year,” but I plan to still chug along with it until I feel that I'm done. It's been fun so far.
Here are some stats:
- 371 days of continuous development (avg. one hour per day, more on the weekends)
- 75,868 additions / 47,902 deletions
- 7,846 lines of code (core application, mostly C++ w/ Qt)
- 2,887 commits
- 352 tickets
- 247 closed
- 105 open
- 43 more issues until the next one
- 12 (active) branches
- 1 (and a 1/2) milestones completed
- 1 contributor (me)
I was planning on doing another post after Imagine RIT, but I've been pretty busy. I was able to display off MEGA_MATRIX there along with a small fork of Blit where you can create animations then upload them to the device. It's was pretty popular with the kids. I'll be posting some of the creations soon enough.
Speaking of Blit I have been still working on it daily since the first release back in February. The big thing that I had to do was refactor the underlying monolithic Animation module into a more flexible and reusable system.
Some small stats:
- 3.5 months
- +1,100 lines of code (exactly)
- 655 commits
- 51 tickets (felt like 151)
I've also done a few other things like add a shape tool, line tool, fill tool (you know, the basics), and a few icons. There are many other features that I want to add too like exporting to GIF and video files. I think I'll be able to get them done for P-2.
It's been a while since my last update. In that time, I've been working on a few projects here in there. As for MEGA_MATRIX, I've added support for the Arduino MEGA and have been able to do a few proof of concept stuff for the Raspberry Pi. The Pi version right now can get a whopping 20K FPS in the native C version! The Pi version isn't too functional right now, but expect soon enough. Link to source on GitHub.
Since the end of the summer, I've been working on my own Animation tool. It's not much right now, but you can find Linux and OS X binaries right over here. Here's the first thing I was able to make with it, a bouncing ball:
I've been a little bored while waiting for the parts and tools to come in for my January project. After playing Fez and trying out the stereoscopy mode, I decided to pass the time by trying to add the feature to my 3D cube.
Stereoscopy works by creating two cameras, one for the right eye and one for the left. These two cameras are a small distance apart. Each of them will see a slight different image/projection of the 3D objects. An image from anSGI tutorial written by Paul Bourke gives a great visualization:
There are multiple ways to view the right and left images. Probably the most common is the use of red and cyan filters. Though systems like the RealD 3D use polarized light to achieve this effect. The first method has significant color quality loss on images, where as the later has much less loss. The reason why the first method is much more prevalent is that it is much cheaper and easier to do. E.g., it doesn't require any extra equipment (sans the glasses) and is not to difficult to implement. Systems like Nintendo's 3DS use a phenomenon known as Autosteroscopy that doesn't require glasses, this is achieved by having Lenticular Lenses applied to the display. It's pretty nifty, and the quality isn't too bad, but there is there are the slight problems that it is more expensive and the viewer need to be in a “sweet spot,” to see the 3D image.
I decided to go with the red/cyan image method. In the current state of my 3D cube program, I don't have anything complicated like cameras added in, so to get this working I did this:
p = a perspective projected line q = an oblique projection on p, with theta = PI / 180, and a small skew value on the x component r = an oblique projection on p, with theta = PI, and a small skew value on the x component color q with blue color r with red draw q draw r
It's definitely an improper method, NEVER DO THIS, but it does give off the effect. I updated the repo page in case you want to view the source. Just change the variable
renderStereo to be
Finals are over and I'm back at home now. I haven't really had a nice long break in the past 2-3 years, so I'm really looking forward to these next five weeks. I'm currently waiting for from stuff from Amazon to work on my project for the break (I'll make a separate post later).
When the line width of the cube was at the size of "1," it's pretty hard to see, but when you scale up the size, it's clearly visible. To fix this, I employed a simple algorithm:
sortedLines = List of "Line," objects zLineMap = Key-Value map of floating points and a List of "Line," objects For each line: Look at the z coordinates of each endpoint of the line zMin = Take the lesser of the two z's If zMin is a key already in zLineMap: Append it to the List at zLineMap[zMin] Else: Create a new list containing only the line Add it to zLineMap at key zMin (i.e. zLineMap[zMin]) zKeys = sorted List of the keys in zLineMap (ascending) i = 0 For each key in zKeys: For each line in zLineMap[key]: Put the line into sortedLines at i (i.e. sortedLines[i] = line) increment i by 1
This algorithm might not be the most efficient (mostly likely because I haven't formally studied any computer graphics), but it avoids the issue of accidentally drawing an impossible cube. This bug was happening because I had an array of lines, would apply a rotation "matrix," to them, then sent them off to be drawn. The drawing function would process them in the order that they were indexed. Sometimes it would look right, but most of the time it would not.