Spooky Pooky #38 - Events, sort of

Published on 24 Jan 2016 by Joe

A little update this week.

I've accidentally implemented some kind of poor-man's event system. Dang, half-arsed-framework-evolving-warning.

It all started when I noticed that when the hero is exploded out of a container jar I had no easy (i.e. generic) way of switching his animation from 'look shocked and concerned' to 'act casual and wait to run around'.

So I wanted things to know when they were freed from a container. Things in this eclectic code base are represented by a single struct called an Entity. Until now I had a bunch of function pointers for custom methods to think, render and handle collisions (actually two handlers for this for collisions between entities and collisions between an entity and tiles).

(Did I mention that I'm writing this in C? Ok, ok. I'll be a good chap and won't bang on about it.)

Reluctant to add another function pointer, I've replaced the collision functions with a single event handler pointer that takes an Event structure.

Event types include 'triggered' (bit vague), 'collision', 'tile collision' and now 'contained' and 'released'.

To avoid calling event handlers on things that don't care about events (i.e. most things), entities also specify a bitmask indicating which events they want to be told about. E.g. the player entity has mask of EVT_COLLISION | EVT_RELEASED.

So after all that I now have a logical place to put a bit of code that stops the player looking so worried when he's just exploded out of a jar.

Take heed. This is why games aren't finished.

Published on 24 Jan 2016 by Joe
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