Doubts about adding force feedback to games

[mickael28]

I've seen that some games, either arcade dumps or games run via emulators, have added force feedback.

By reading other posts it seems that this function needs to be programmed specifically for that PC version. I don't have a clue how you guys know what needs to be touched to be able to change the original behaviour of a dump (without force feedback for a PC system) and create a library or similar to include such support. I'm just grateful that some of you know

If someone has ever done anything similar or knows:

• what is the trickiest part for this task (finding what needs to be changed to re-program the force feedback, thinking how to integrate the new code with the original game, programme the force feedback itself)?
• and how long could it take to take all those tasks and have a final version, I guess this will depend on the game and so many other factors, but for example with 1h/day for the task, would we be talking about a few days, weeks, months?

 

[Popcorrin]

send a pm to howardcasto.  I know he has done some extensive work with force feedback and I know it wasn't easy.

[mickael28]

Yeah, I saw the awesome work he did for the whole community with Outrun. In fact, that's how I discovered the forum...

I was wondering when I found out Daytona USA and Scud Race with force feedback as well but others without it, but by the looking of things, I think that most of us do not even know how one could start and even if we knew, it would be quite a lengthy process so most likely it's not going to happen for most of the games which have been available for a while but didn't offered that feature by default I suppose.

I guess we'll appreciate more the ones which do have it...

[Howard_Casto]

First off there are "games" and there are "emulated games".  As in a legitimate pc release or arcade games.  Most pc games support some sort of force-feedback and/or xinput rumble by default.  Zero arcade games support force-feedback because that's a Microsoft thing.  The exception being, of course a few very modern games that just use a usb interface, but even then they usually use some kind of proprietary board to prevent piracy.

Arcade games usually directly drive a motor or a series of motors via an interface board... depending upon the physical hardware setup, what the game sends to a motor(s) won't necessarily translate well to direct-x, which has you define a direction in space, a strength and a duration, as opposed to arcade interfaces that just send a command to throw positive or negative voltage to a particular motor at a certain strength.  So there is a bit of crafting and artistry involved.  Frankly the guys that did the force-feedback for model 2 and supermodel are far better at this than me.

The few pc games that don't support force feedback have to be hacked.... it's as simple as that.   Myself I read memory locations that give me some values in regards to where the car/player is and what they are doing and send certain effects based on the situation.  It tends to work well for simple arcade racers and some lightgun games but it gets infinitely more complex the more advanced the game is.

Then there is rumble, and true force-feedback.  Atm Outrun FXT and my other projects use canned effects to rumble wheels and gamepads.... true force-feedback is quite difficult to do without a good understanding of physics and full access to the physics of the game.  In terms of learning how to do it... and this is the main reason we don't see more people doing it... you have to figure it out.  While code instances and a variety of functions are well documented, how to use them to create a desired effect isn't.... you need to either have experience in the game industry, or just muddle through like I do. 

So to summarize it's hard to add force-feedback to pc games because you have to find memory locations and craft effects from scratch.  It can be had to add force feedback to arcade games because of the translation process from direct board drive based commands to physics based commands.  Both are difficult in general because force-feedback examples are hard to come by on the internet. 

Even ignoring all of that you've got to understand that I'm a bit of a nut, as are all the people that obsess over force-feedback.  Most people don't care enough to worry about it, including a number of emulator developers.  It's "low priority" as they say. 

[mickael28]

Thanks for the detailed explanation @Howard, I've learnt quite a few things from there. It all starts as a hobby and the more one knows, the more one wants to learn...

It all seems too complex to really learn about how to do anything, other than just keep an eye into the FFB/rumble space in case something new gets released...

Thanks!