This week I worked on two separate goals and although I finished them both neither are easy to graphically demo in a video format.

This week…

  • Support For More Complex Electronic Systems
  • Physics Joints/Constraints

So Why No Video?

The two things I worked on this week are two completely separate systems which I need for what I plan to do next week, unfortunately neither are particularly graphical in nature and so I can’t really demo them in a video!

Complex Electronics

I started off the week working on the electronics for doors. This is a surprisingly complicated set of systems including:

  • Sensors to detect if the player pressed ‘use’ on the door to open/close it
  • (pickable) Lock mechanisms
  • Lock control mechanisms (e.g. a code panel as I showed last week)
  • Timers (electronic code panel unlocks door for a set time before closing it and relocking)
  • Motors to open/close the door

None of these is particularly complex on it’s own, but together that’s quite a lot of parts to put together (and of course to debug the underlying electronics framework). It didn’t take me long building these circuits to realise that I had a couple of problems.

1. The Electronics System Was A System Of Devices With One Input And One Output.

This is a bit of a problem! It was possible to work around the limitation by building a device out of multiple interconnected devices and so you could have a load of input devices connected to some logic and a single output device but this was a colossal pain in the ass to work with! It took me a couple of days to refactor the electronic infrastructure system to remove this limitation and then to rebuild a load of devices (which had previously been multiple partial-devices) into single devices. For example Electronic Infrastructure now has a much easier to use boolean logic system (And, Or, Not, Xor etc).

2. Building Circuitry Was Very Repetitive

A timed latch is a pretty simple device consisting of 2 inputs, 1 output and 3 components and 9 connections (i.e. 15 line of code at least). This a fair amount of boilerplate code to have to write every single time you want to use a basic circuit like a timed latch and the same logic extends to any commonly reusable circuitry. To fix this problem I extended the circuitry definition system so that you can use circuits as devices themselves - so now you can define a timed latch circuit and use it in other circuits.

Physics Joints/Constraints

Previously I have built a lot of support for asking the physics engine about the scene - raycasts and volume queries etc. What I haven’t done very well up until now was build support for creating complicated setups within the physics engine - basically I was lacking support for all the joints and constraints you need to build interesting things (like doors, with sliders, motors and hinges). I spent the rest of the week refactoring the (very basic) support I already had in place for constraints (previously used only in the character controller) and expanding it out to support many more types of joints. By the end of Monday I should have support for every single type of joint in the BEPU engine (about 20).

Why Do You Keep Talking About Doors?

My goal for all of this is to build a set of doors with locks, keys, code panels, motors, sensors and alarms (obviously this is pretty important for a game about breaking into buildings). I now have all the separate parts to do this built into the engine and scripting system - it’s just a matter of assembling the parts together in the right way now!

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