četvrtak, 19. svibnja 2016.

New star

It's a funny story how drawing a star has bothered me from the very start of Stareater project to the recent days. I'm not good at drawing stuff by hand so did next best thing, I made program do the drawing for me.

First one was simple, it generated a texture (image) with each pixel painted according to a certain formula and displayed it. Any change in star shape or color required changing the code and rerunning the program. Actually using the resulting image in game was a bit complicated. Back in a day I didn't know about PNG so I did screenshots of each star color variant, pasted it in MS Paint, saved as BMP, loaded in GIF editing program (which name escapes me and) and marked black as transparent. This is how it ended up looking:

Bottom row is how it looks in the game, mostly OK but could be better. Edge between star color and darkness of space is too prominent especially in the case of red.White center is invisible in yellow star and too prominent in blue. Top row demonstrates functional problem with the whole thing, since GIF has so called key based transparency (all pixels with "key" color are treated as transparent) there was no way to make some pixels semitransparent and if the star was on top of something then the fake space darkness would become visible.

At the time it served the purpose and after a while I decided to fix those shortcomings. I've made a more complex program which could save usable PNGs and could change parameters on the fly. It had a little framework for making procedural images generators and star image was just one implementation of the framework. Each image generator had it's own logic and set of parameters on GUI and the best thing was that one of the supported parameter types was symbolic function. You could type "4*x+0.5*y" if x and y were applicable variables and it would work.

Above are examples of some image generators and as I said, star image was just one of them. I also used the program for experimenting and fine tuning Stareater algorithms like starlane generator (middle image) and star positioning (right image). It was great tool for making quickly visualization.

On the other end I was exploring vector graphics for drawing starships. Inkscape was the best and de facto the only good tool for the job but it didn't click with me. It's great for hand drawing, so to speak, but lacking for technical drawing which happens to be my way of thinking when it comes to drawing something bigger then 20x20 pixel art. So I started making my own program for vector graphics, it was no good so I made another with different approach, it was better but not up to a task and repeated the process a few more times. The thing evolved from clicking points on canvas to typing them in table to writing a sort of programming language. Seriously:

On the right side is code, a sequence of points and shapes made with those points and on the left side is resulting image. It was not the most polished tool but it had potential. Unfortunately it took a lot of effort to keep improving it and code editor was devoid of usual IDE (code editor) luxuries like autocompletion and syntax highlighting. As I was developing programs in SharpDevelop, an opensource IDE, I was pondering an idea of using their code editor for my vector graphics language. And then I took the idea even further, to use C# itself for drawing. On the one end I'd to develop image generator as DLL (much like other Stareater plugins for AI and map shapes) and on the other end was program which continually monitored if DLL has changed, loaded new version of image generator and displayed a resulting image.

It's kind of return to the first program I had back in 2008 but with much faster code to image loop and so far it's serving me well. There is a bit of initial setup overhead for establishing OpenGL logic (making texture, setting perspective, setting rendering flags and drawing textured rectangles) but once set up it really easy to adjust and experiment about. Especially when secondary monitor is available, put C# editor on main screen, image preview on the other and watch the image change as you type.

And there is one more important bit of the story. While I was making all those programs I was collecting images of real stars in order to figure out what to actually draw with my programs. The challenge was to find an image were star was not a simple globe of light and not overly distorted by atmospheric noise and lens. When I finally made a satisfactory program and picked a good looking star the real fun has began, analyzing how colors change from black to blue to white and how to make similar looking stars of different colors. That part might be too geeky so I'll just leave a picture without too much explanation: