Archive for the ‘Code’ Category


LD19: Drill Warrior

19th Ludum Dare contest was held already back in December. Since I managed to make an entry this time, I figured out I could post about it before the next one is held, which will be probably next month.

The theme was “Discovery”. Description, downloadable Windows build and source code of my game Drill Warrior can be downloaded from the separate page about the game.


Various ways to backup

Over the years I have been using several kinds of solutions to backup stuff. Here’s a description of the ones I can remember. Many of them focus on being low-cost, simple and straightforward, but are far from a perfect solution in many other ways.



Unwrapping Values – nearest next angle from a previous angle

So, assuming you have angles previousAngle and nextAngle, and you want to transition from the first to the second smoothly. If it’s like from 358 to 2, a simple linear interpolation will awfully go through almost a full circle down from 358 to 2, when a simple four degree transition forward would have been enough, i.e. you should have been going to 362 degrees instead. So, how to figure out what’s the shortest transition?

I remember hitting against this problem numerous times, always remembering that I have solved it previously but always seem unable to find the previous solution. And I still can’t just write it out by heart.

Once again I had to solve this, so this time I tried to Google for it (“angle wrap delta”), and found out that somebody named Jason S had posted a nice generalization to a related question in

For your convenience, I’m posting a modified C version of the code here.


Little framework for making prototypes or an LD48 entry

If you didn’t know yet, the Ludum Dare 48 hour game development competition is held again this weekend. In the competition the idea is to make a game using a given theme, more or less from scratch. Basically most people use some small amount basecode to start up with as there’s not really that much point to make every boring bit (like how to open a window) again every time. Besides, a little framework still has less stuff than what fine tools such as Unity3D provides you with to start with. :)

So here’s my little C++ basecode/framework for making a Ludum Dare 48 hour game development competition entry. It should be equally suitable for making some other little prototype games. You’ll need to svn checkout Irrlicht and download FMOD 3 separately. The framework is meant to be used on Windows with Microsoft Visual C++ 2008 (Express Edition is enough).


Code: Tokenizer

Here’s a little C++ utility class for splitting C strings into tokens by given separators. It’s inspired by “tokenwad” taken from Sol’s CFL3, which I have used quite a few times. This version has low memory overhead as it performs only 1-2 allocations (depending if the tokenization is done in-place or a separate copy is needed).



Tool: Binary data to embeddable char array

Sometimes there’s a need to embed some little bit of binary data in the executable. The reasons may vary – perhaps it is for a resource you want to exist even if data files are missing, or it could be even something you want to “hide” from some curious wannabe-hackers.

In the past years my typical use case was as follows. I used to make “64 KB intros” (such as this one), and for those I needed to embed a few data files to the executable as object data, so that I could exploit compression of the executable packer without writing a proper compression tool myself (such as UPX).



Tool: pngprep

When programming visuals, I often need to fix color values of pixels in image data where alpha is 0. Here’s a little tool called pngprep which can do some pre-processing of image data and save the result as a 32 bpp png file.


Tool update: psdslayer 1.1

A while ago I posted psdlayerstga 1.0. I have now updated it to support saving to PNG files, which is also now the default output format. The tool also got renamed to psdslayer, since I was constantly imagining, and even mistyping, the name to be “psd slayer” rather than “psd layers“. And I find it funny.


Steps and Pulses

A few years ago I read the book Texturing and Modeling: A Procedural Approach (Ebert et al.) and found some low level “step” and “pulse” primitives used for generating procedural graphics. It didn’t take a long time to notice that those are actually really useful in many other situations as well.

A generic pattern is that some value changes its value from a to b over t iterations, and you want something other to move along from c to d in the same time. Implementation is easier when the transition from a to b is just normalized to [0..1]. After that it’s really easy to map it to any range just by another multiplication (dc) and adding an offset (c).

The “boxStep” function does the normalization part described above. However, just linear movement is actually quite boring, so the funky part here is that you can just switch “boxStep” to a “smoothStep” and there we go, movement along a smooth curve which feels better. Or you can map the boxStep result to a different function which takes in a value in the [0..1] range and outputs a value in the same range, e.g. sqrt().



Tool: psdlayerstga

UPDATE: psdlayerstga has been renamed to psdslayer with addition of saving the layers as png files. Get the new tool from here.

I took DrPetter’s PSDImage code for extracting layers from PSD images, and combined it with stb_image just for saving out the layers easily as TGA files. And then I included some simple options and output of the metadata (i.e. name and position of each layer). Result is a little command-line utility, “psdlayerstga”. Use it for anything, but do so at your own risk. (The PSDImage code uses that same license, and stb_image is public domain.)

Download here, including C/C++ source and a pre-built executable for windows:
Go get newer version (psdslayer) from here.

Edit: Don’t miss psdparse below (suggested by Toby), an alternative tool for the same task.