Re: Incorporating my project into a robot car.

Hi Henry

> In short my plan has been to produce my project in C# (a language I'm
> more comfortable in than C++) and use COM to provide a bridge between
> the two languages. I've developed a bridge class for C++ which does
> successfully gets the basic bits of info I need across and everything
> operates fine. The bit I've come slightly unstuck with (and would really
> appreciate help with) is linking my bridge class into the berniw
> tutorial robot. (Or any other suitable robot!)

Ok, if I get it right it you just need to call you custom COM stuff from 
the robot. Depending on your requirements you have to decide somewhere 
between these 2 extreme cases:
1. The c++ robot acts only as "COM bridge" and all decisions are made in C#.
2. The robot is fully in C++ and just calls you specific learning 
algorithms via COM.

1 requires some work to bring all data you need through the COM 
interface, there you have to decide up to what level this is beneficial 
(tradeoff, as usual...).

2 should be very easy, but it might not fit your requirements (e.g. if 
your C# robot should be general and requires a clean interface/own 
datastructures to plug it into other simulations, so you need to map the 
data anyway).

A comment to the COM interface: COM is not portable, maybe a TCP/UDP 
approach might be better (e.g. see this: 
http://cig.ws.dei.polimi.it/?page_id=134 and 
http://sourceforge.net/projects/cig/ and 
http://games.ws.dei.polimi.it/competitions/scr/.

Beware, there could be another easy way (I did this in the past):
- Compile your robot as "Managed C++ assembly", because it is a DLL and 
the interface to TORCS stays "as is" it does not matter for TORCS. Then 
you can access your C# assemblies more or less without a fuss, IIRC.

To the technical stuff (to the COM idea):
- I would recommend you to compile TORCS with VS2008, it should be easy 
to link you C++ robot to COM (I did something similar years ago in a 
commercial software project, IIRC it is pretty easy, so just use Google 
and MSDN documentation).

> What I need to be able to do is to access the robot's steering angle,
> the velocity, the position along the track (in a single dimensional
> length if possible?) and the car's lap time. I would also need to access
> and modify the robot's brake and acceleration levels and the damage

This is all easy to find, just sneak into the robot tutorial, steering 
angle/velocity is chapter 1 I guess, the position along the track is 
car->_distFromStartLine (see also 
src/libs/raceengineclient/raceengine.cpp, around line 344 in TORCS 1.3.3).

> meter for the car. (My project is looking into whether Reinforcement
> Learning Methods would allow the car to adjust to wearing brakes, I'm
> using the damage to keep track of the brake wear.)

If you want to implement brake wear you should do it in the simulation 
engine (see src/modules/simu/simuv2). You should then add new fields to 
the car structures to keep track of it.

> It might also be useful to know when the lap ends (however if I know how
> far along the lap the car is, and the length of the track I can work
> that out from those two bits of data).

As above, sneak into src/libs/raceengineclient/raceengine.cpp.

You should as well have a look into the FAQ here:
http://torcs.sourceforge.net/index.php?name=Sections&op=viewarticle&artid=30#c6_1, 
6.7 and 6.8 might be interesting for you.

> Thanks in advance,
> Henry

You are welcome, let us know if this helped and how you solved it 
finally such that others can learn from it.

Best regards

Bernhard

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