Tuesday, 28 July 2015

Game# 13: How it works

Hi. I'm back from a sunny week in Germany. Remarkably I've lost weight on Holiday, because the place we stayed is on a steep hill in a river valley (Heimbach in the West of Germany), so lots of climbing up and down.

Anyway, how Jawbreaker works.

Globals and Constants

Lots of globals and constants here. Have some quasi constants as well "Pseudo Constants" - the idea here is they are assigned one value at the start, which then is unchanging - obviously this isn't enforceable in C2 but it's a good idea code wise. Event 3 initialises these values which represent various screen positions.

There are some utility functions here, updating the score and lives, and resetting things when a new game/retry occurs. When you start a new level or game, the layout is reloaded.

Finally this game has an FSM, which was grafted on afterwards, lazily :)


This game doesn't usee the painting at all, pretty much, so this sets up the screen - event 1 draws the border, repositions the vitamin (it is always there, just not always visible) and the level text. Event 2 creates the moving walls (actually solid walls with a black overlay), and event 3,4 and 5 create the monsters and the sweets.

Play State, 

This is the main game stuff. Event 1 initialises everything on layout start. Events 2-4 control the music and the 8 direction controls depending on whether the game is actually being played.

The game code proper starts at event 5.  Event 6 clamps the player into the game space, and 7 and 8 handle the potential horizontal movement - this is only permitted either in the left or right columns, or where you are passing through a gateway (gap in the wall).

Event 9 through 13 handle eating sweets - 10/11 have different effects for eating the different coloured sweets, and 13 handles the end of level.

Event 14 makes the vitamin pill appear on its timer, and 15 and 16 make it go into chase mode on collision with appropriate sound and effects, also setting the timer for "end of chase warning" (fired at 17-18) and "end of chase" (fired at 19-23). This also puts the monsters to reappear at the other end of the game board from where you are, allowing the player to get away (i.e. monsters don't reappear on top of you)

Finally 24-26 handle collisions with monsters - this can either be during the chase mode (26) in which case you score, or not, when you lose a life.


This handles the monsters.  Events 2-4 set up the monstes, with a position and a reverse timer - they are driven by wrapped bullets. On event 5, the monsters reverse direction periodically.

Event 6 shouldn't be here (arguably), it's purpose is to make the gateways invisible or visible depending on the horizontal position, otherwise they will appear over the top of the left and right border. I probably should have done his with z-order/layers, but it's a blitz.

Other states

This handles various states. "New level" (1-7) animates the brush coming in and brushing and out using a bullet and a sine. This is messy but it works by firing timers and checking the position.

Event 8 onwards handles lost life, and this makes the player disappear from the top down. Finally Game over, in events 15-18 fades the Game Over text in and goes back to the title page when the fade is completed.

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