Saturday, November 13, 2010

Side Scrolling Fun V: Music, Levels, Bosses, and Media Managers

The next iteration of the side-scroller engine is up and running, and is almost starting to resemble an actual game. The first thing I did was find out why the game took so long to load. The answer was simple - I was being stupid: each instance of image and sound in the game was being loaded each time it was needed. In other words, I had roughly 3000 tiles consisting of one of 3 distinct images. When the level was loaded I loaded each image separately from the server, i.e. I downloaded ~3000 image per level, while in fact I needed to download three. To get around this, I wrote a ImageManager (iMan) class. Each time an Image is needed you ask the iMan for it and give it only the filename. The iMan checks its database to see if that file has been loaded yet. If it has, it returns a copy of the image, only if it has never loaded that image does it request it from the server. This lead to a tremendous speed-up in loading time and seems to work fine.

The next fish to fry was sound - both sound effects and soundtracks. I started by making a sound manager (sMan) similar to the image manager. Next I had some struggle with sound formats. Java doesn't care much for wav files. I basically had to tinker with the bit-rate, depth, etc. to get it to play, and I still don't know why some play and some don't. All I can say is that the java native sound engine is good, but finicky. As for sound track, I went for straight up midi which was a lot easier to work with. Currently, all the songs are ripped off from an awesome repository of nes roms that I came accross and I am starting to try to "compose the original score" :)

The next task was to create game states that allowed specific tasks to occur (ex. loading, player just died, player is playing, etc.) This allowed for an intro screen when the game was loading and cut-scenes between levels. This also allowed for animations and sound clips to run when the player dies or beats a level. The paint and run methods are then if-else statements based on the current state. The states are:
  1. Intro
  2. LoadIntro
  3. LoadLevel
  4. Playing
  5. JustDied
  6. Boss
  7. JustPassed
The next improvement was the addition of levelguys, i.e. bosses. In boss mode a life-meter pops up displaying the boss' health as the gameState is set to "Boss". The screen also locks and the music changes. After the boss' energy reaches -1, the gamestate goes to justpassed and some celebratory music (currently from Duper Mario Bros.) plays. In order to mediate the timing of the cut-scenes, there is a variable tickCounter which is set when the game enters a given mode. When in this mode, each tick of the game loop reduces the tick-counter by one so that when it reaches zero, a new game state may be entered.

The boss can be seen here. He's (it's a dude) pretty easy and used for debugging purposes.



Here's screen shot of the the game in action: Click it to play!


The source code for this version can be found here. The "game" can be "played" here.

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