Tiny Sketch compo entry

There’s this Tiny Sketch compo and I made a silly little contribution to it. I can’t get it to embed into this blog (and it’s too late for me to try too hard) so here’s a link to it. Enjoy.

Green hills

I found this isometric drawing tool called halfshag and doodled a bit with it, though towards the end it became rather slow and a bit buggy. It also lacks proper blue colored bricks, so my river had to be red, but I hope it’s visible that this wants to be a hill scene. Oh well, try it if you want. Here’s my doodle.

Doodles

The reason I started this blog was that I wanted to do some very short and fun coding projects and I figured that rewriting old effects would be fun. But now I was inspired by some photos to code some simple geometric objects so here is the first doodle. Of course, I ran out of patience long before I could achieve any worthy similarity, but at least I can easily rotate the thing.

Another thing is, that I wanted to keep this blog rant free, but maybe these doodles allow me to rant a bit, as there’s no common topic about them and their implementation is not interesting from an educational point of view (I did try to concisely describe the theory behind the effects I coded so far, but of course I have no hope that I managed to). Anyway, it’s very likely that this blog will take a break for around 9 months as I should save my coding juices for work.

4k intros containing fractals from Assembly ‘94

Seems like fractals were very popular at Assembly ‘94 so I tried to review all those 4k intros that had a fractal effect.

Stoned by Dust. It starts with a rotozoom of a Mandelbrot set, but it never zooms in more than 2 times, so it’s probably a simply precalculated picture (you can do the rotozooming of the Mandelbrot set by applying the transformation on the parameters of the generating funtion).

Then a pretty interesting tunnel comes, and finally a greeting to all ASM’94 attenders with a ripple effect. This is a true classic (like everything else from ASM’94, pouet doesn’t even list graphics or music).

Optimize by Epical. This intro has a lot of effects, probably what turned it down from winning was the strange choice of a brown palette for most parts (especially the fractal ones). At first, there is a fire effect that burns aways the introductory text, then a pretty nice plasma follows with big waves and nice colors.

Then some vertical rasterbars come, then some other raster effect that I am not sure how is called, I think it was very popular on Amiga and it was made with the copper function of the graphics chip, but I am really not sure about it, but here is a screenshot.

After this, the fractal parts come, first a rotozoomer with a Mandelbrot set texture, then a lens over a picture of a Mandelbrot set and at the end, even a Wolf 3d part can be seen, though I am not sure if it was made by raycasting, sometimes pretty big gaps can be seen between the wall parts, I believe with suitable fixed point arithmetic they could be avoided when raycasting. The walls are textured with Mandelbrot sets, in green for a change.

Fractals by Schwartz. This intro has the nicest introduction part and a considerable precalculation time too. First, some less common parts of the Mandelbrot set are stretched on the screen with blue and green palettes.

Then an interesting effect comes, I believe it’s a plasma where the height is not a simple summation of some constituent functions, but only the largest constituent is taken into account. It moves like a plasma that’s why I believe it is one but I haven’t seen many effects like it.

In the end, there is a tunnel effect that shows some Mandelbrot sets, I believe it goes infinitely, I had to press esc after a good while.

Fractal Dreams by Mental Design. All this intro does is show some nice fractal landscapes but they’re so nice that I included them all.

Move by Surprise!Productions. This intro has a Star Wars type scoller in the beginning, announcing it to be *MOVE* and actually, the camera does really move nicely throughout the whole intro and the linking of parts is done pretty nicely during these camera movements. All the textures are Mandelbrot sets in this intro too. First, there are two planes (I am having a hard time naming this effect I would call it infinite plane to imply that we have a perspective mapping of the planes and they fade out into the infinite, but then, mathematically, a plane is infinite so I’ll just call it plane, and besides, there are “color planes” too, though I am not sure I’ll ever go back that far in time and review ega demos too ), that are are rotating in counter directions.

Then, a simple voxel comes, that doesn’t move that much in the old fashioned overview mode and has some huge texel to pixel ratio, but actually, it looks very good this way.

An interesting thing about this intro that it actually runs in a 512*384 pixel mode (at least dosbox made screenshots of this size) that was a huge area to fill in 94, probably they don’t do full redraws in the voxel part.

Fractal revolution by Xography. The last intro in the series, it includes a fractal zoom with very visible fake in-betweens.

Julia set

The Julia set is calculated very similarly to the Mandelbrot set, though it is a somewhat different mathematical object.

In both cases, we iterate the function but in the Mandelbrot set case we explore the constants and always start from x=0, while in the Julia set case we explore a rectangular area of the complex plane. In this case, we can play around with the constant c. Usually in demos the static nature of the Mandelbrot set is explored by zooming, while the dynamism of the Julia set is explored by changing the constant. Computationally, they are both the same (more or less ) but zooming can be faked easier, so maybe that’s why Mandelbrot sets are more frequent in demos. Also, finding a good palette for Julia sets is harder I believe, because finding meaningful constants is not a trivial task as the set usually looks like a single colored blob, the finer details are visible only with carefully chosen constants.

Bobworm

Bobworm is a funny little effect and it’s perfect to kick off a new year with (because it’s easy to implement so you can still savour the holiday lazyness while still producing “something” ). There is one small problem with it, a nice little bob (or sprite, if you wish) is needed that will wander around the screen and that may be a bit hard to find nowadays (in my case, lazyness is the problem again, as I don’t feel like messing with my backup cds that most certainly have many cute little graphics). So, while browsing the net, I found this postscript hacking page of Andrew Cumming and I had a little fun with it. I noticed that it has the possibility to display balls too, so I made a .ps file with only one ball, converted it to .gif and cropped it manually and so I had a nice bob. There was just one problem with it, the picture is of course a square and the ball is round, so the extra pixels around the ball are ruining the effect when balls are displayed on top of each other, so a bit of extra code is needed to zero the alpha of the pixels that don’t belong to the ball, luckily, a circle is a rather simple geometric object. Though it took me some time to do this, because I wanted to somehow solve this with Processing functions and also the blending took a bit to figure out. Somehow I find working with background buffers in Processing not as easy as it should be, but probably I’m missing something. This may not be the easiest way to make a nice pixel ball (probably it would have taken me less time if I pixel it myself), but why not do it the complicated way?

So after all the setup, the effect is easy to do. The trick is to use 4 background buffers and swap them in every frame so the ball is drawn on each buffer only every 4th frame. As the eye is a bit slow and the change is minor, this will look like a continuous motion so there is no need to keep track of all the previously drawn bobs and especially no need to redraw them. No wonder this was a pretty common effect back in the 8 bit era, though maybe I am wrong and it was solved on some systems with sprite multiplexing. There is only one more problem to be solved, what path should the bob follow? Well, in Processing there are functions for calculating splines to it’s easy to generate pretty smooth random curves (though as the length of the parts is not equal, sometimes they look bad).

Mental Debug

This demo from The Party ‘96 made by Dead:beef was one of those, that always froze on me after the first part, had only GUS support, so it was a real pleasure to be able to fully enjoy it with the help of Dosbox.

The first part is really moody, it is a night scene of a city that unfolds into a car chase. It has a bit of GTA touch, only this is years ahead of the game. I really liked this scene, the poly count and depth of scene was amazing for that time, shiny rotating objects were still common back then. After the driver of the car is revealed (if you don’t know who it is, I recommend watching the demo ), the demo always froze for me so for a long time it was on my wish list to see how the story unfolds. Dosbox had some bugs emulating the 3D engine code so some textures are not drawn and the clearing of the screen causes some blinking, but it’s still enjoyable for those, who like watching old software renderers taking themselves serious. Well, no big 3D scenes follow, but it’s still fun to watch some low-poly, lightmapped models with some simple keyframe animation.

There are three more effects, the last effect is a bit distorted rotozoomer with a noise type texture, but there’s also a story told of somebody walking in the woods by morphing still frames of stop motion frames. The frames are also heavily post processed to use just a few colors and give a very painterly look with strongly contrasting areas. I don’t know if I’ve seen this effect elsewhere, but I will look for it.

There is also this shiny light coming out of the middle of the screen, I don’t know exactly how it’s done but it was very popular, it was the predecessor of volumetric lights with some foreground I think. I would do it with as tunnel type effect, so I tag it like that too.

The Message From The Cosmic Brothers

This is a video demo by Complex from Assembly ‘94. I like it because of the ambiance it creates, the music is very interesting. The demo is made of short clips that are probably magnified four times to fill most of the screen and rendered with a bit of alias, and use a very aggressive color quantization, some of them are probably not filmed by the creators of the demo, others are theirs, there’s no real concept, except maybe for the “greetings” sent to Asm organizers and FC. However, playing the same stuff with very different color schemes and the music create an interesting mood, I find it worth watching, maybe the brutality of the video compression adds a lot to this, the action on screen is not very telling.

xmess

It’s holiday season, so this little 64k intro from The Party ‘96 is very fitting. I like it because of the funny tune and the cute Lemmings style animation, though there’s not much else in it. A nice break from the usual stuff, though.

Jenny thinks

This demo was made quite recently (2004) by Fit and Bandwagon and it’s available for 9 platforms, including the two GamePark consoles (GP32, GP2X) and Dreamcast. It’s mainly a video demo, so I tagged it with video filtering, and it has that film roll effect that makes you see the roll of film that’s scrolling upwards with a different speed than the screen refresh, so you can see the individual frames moving upwards for a while, and then downwards. Plus there are a few bits of simple effects, like feedback and blur, and also some kind of a plasma or some texture warping effect, it’s hard to tell as it’s using only two colors. An interesting feature of this demo is that it uses movie clips that are public domain now and the music is using some of those samples too, so there’s speech that I usually don’t like in a demo but in this context it works really well, I would say it’s quite and enjoyable demo, maybe because of it’s simplicity (mostly black and white).