About Warp by the author, Karl Hörnell,

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How to play

This part is so simple it doesn't really warrant any explanation. Shoot at everything that moves and some of the things that don't. You'll soon learn which objects can be blown up and which ones just absorb the blasts. Avoid flying into anything that looks bulky and sticks out of the ground.

Keep in mind that most Java-enabled browsers require that the cursor is located within the current applet area for the keyboard input to be directed to the applet. Some may even insist on an initial mouse click.

How to cheat

I didn't spend weeks preparing the graphics of Warp just to have them gather dust because most people are too lousy players to get any further than level one. You can start any of the first five levels by pressing the SHIFT key plus A, B, C, D or E.

Platform-specific problems

On certain machines with slow graphics cards but fast processors, the "curtain" effect between levels and when losing a life will not look right. It will appear to take only two or three steps before the screen goes blank. This is because the main loop has a period of no less than 70 milliseconds and the computer can't redraw the screen that often, so it will simply ignore the update request and wait for the next one ... or the next after that. However, during actual play, the loop has a lot more to do and will usually be delayed for so many extra milliseconds that the computer does have time to carry out the updates.

Technical stuff

Although each level is more than ten screens long (and can be made any size) the graphics area that stores the background is in fact just a little over two screens. Think of the current view as a window that moves upward along the graphics area. New ground is continuously being drawn above the window. At the same time an exact replica is drawn below it, so that when the window reaches the top of the graphics area it can jump down to the bottom and continue seamlessly from there. The cost of this on-the-fly graphics updating is (at most) one Graphics.drawImage operation per animation cycle and it saves a tremendous amount of memory.

Another memory-saving strategy I've used in Warp is to load the graphics of each new level separately and throw them away when they are no longer needed. This dramatically cuts down on the number of Image objects the applet needs to allocate and of course reduces the download time for netsurfers who weren't going to play all nine levels anyway. (I was actually forced to do this because the game would have been too big to run on my humble Macintosh Performa 6200 otherwise.)

To make the scrolling as smooth as possible, I don't update the score display and the blasted stationary objects immediately, but wait until the graphics updating has a spare cycle. I'm not sure exactly how much effect this has, but on slow machines I suppose every little bit helps.

Ingredients

Warp needs ten graphics files - one for each level and one that holds the parts that make up the control panel and the things that remain constant at each level, like explosions. They are named warp0.gif through warp9.gif and can be found in the current directory. The game also needs sounds. KA-PEOOO!, CRASH! and BING! come in individual audio files named warpsnd0.au, etc.

Source code

This is what the code looks like.


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