leah blogs

December 2005

27dec2005 · Making of: The XMasHack 2005

Maybe you already saw my yearly christmas greeting on ruby-talk:172428 (last year’s to be found here), but today I’d like to explain how I did it. If you didn’t run it yet, do that now and be amazed. ;-)

First of all, I needed to implement the actual logic. I’d only like to outline it here and leave the rest for the reader. You may want to read the complete, unobfusciated source.

The real snowfall happens in snowdrop!, where a random vector of snow heights gets increased by one in a way the difference to the neighbour elements is never greater than one. This vector then gets rendered in to_s onto a marshalled array with the greeting message by differentiating the vector and thereby figuring out which chars to use. Above the skyline snow randomly gets painted.

All this happens until all the vector’s elements are filled up. The logic is not very difficult but I tried quite a few ways to make it work best. I’d like to thank Frixon on #ruby-de for the inspiration; he had to write the mountain algorithm in Ada (I didn’t look at the code, only at the output).

Of course, that was the easy part. ;-) Now, the thing had to be styled. Since this years hack was a lot bigger than last years (2221 byte), I couldn’t simply reuse last years fir tree. I first tried to add some thicker border to it, but then I thought it would be boring if I used the same image twice.

So I took the PostScript star of first advent, gimped it a bit (solid fill, rescaling to an appropriate size and ratio since terminal fonts aren’t 1:1), then saved it into a portable grey map and solarized it into ASCII chars using a self-written script. The rest of the image (border and snow) was made manually using Emacs’ picture-mode.

The final ASCII image, consisting of * and and some custom text was then filled with code, using a similar script like last year.

It was some hours of work, some hours of fun and I hope you enjoyed it!

NP: The Melvins—Revolve

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