Community Question: Should Racing Simulators Prioritise Soft-body Physics?

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BeamNG's class-leading damage model
Soft-body physics has always been a hot topic in the sim racing world, but which simulators could pull it off? What titles would it ruin?

Soft-body physics, or dynamics in the wider reaches of the technology, is a field of simulation that focuses on visually realistic physical simulations of the motion and properties of deformable objects or better known as 'Soft Bodies'.

The most common use of soft body physics within racing simulators is the damage model. Titles such as BeamNG.drive and its predecessor, Rigs of Rods, both show just how detailed and difficult the technology is to master. BeamNG has been in continual development since its release in 2013.

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BeamNG's Soft-body damage model.

BeamNG is the obvious choice for a simulator in which soft-body physics works wonders. Without it, the project would have very little to write home about. But what current sim racing titles and projects would positively benefit from adding in a complex damage model that models both the visual and physical implications of damage realistically?

Could iRacing adopt soft-body physics?​

The sim with the best damage model is often considered to be iRacing, however, their damage model is still far from the level of BeamNG. The iRacing damage model is imposing until you start reaching the deeper levels of detail.

There are not too many chassis dents, just bodywork and mechanical damage that you can feel through your wheel - plus a myriad of parts flying off the cars, as well as wheels being visibly crooked or only hanging on by a tether if they take a solid hit. That being said, the iRacing damage model is certainly a class leader in the world of pure racing simulators currently.

iRacing's new catalogue-wide damage model as of June 2024

So would iRacing benefit from a BeamNG style of soft body physics? We do not think so. The newer damage model suits the simulator perfectly well. Despite lacking detail in some of the more intricate levels of damage detail, iRacing does a fantastic job of simulating what a racing crash looks like - something BeamNG often exaggerates and consequently falls down on.

Why Rally Is The Perfect Candidate​

If you have ever played the iconic rally title Richard Burns Rally, you will know jut how punishing a damage model for this discipline can be. However, modern iterations of rally titles have toned it down a bit when it comes to a comprehensive damage model.

Both DIRT Rally 1 and 2 had a satisfactory damage model with impactful mechanical damage and failures, however, some of the crashes that would have ended your rally at best simply require you to reverse and continue with a slight crack in the windscreen and a missing front bumper.

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Porsche 911, Dirt Rally 2.0. Image: Codemasters

EA Sports WRC
has this same problem. In small and medium-speed accidents, you are punished to a fairly high standard. If you clatter a wall, you will mostly likely damage your bodywork and maybe your suspension. However, a high-speed multi-rollover accident will more than likely not damage your car all that much, and certainly will not cost you a lot of time - even with hardcore damage enabled.

So is the world of rally crying out for soft-body physics? Let's take a short look into BeamNG'drive' s rally world to see if it could work.

BeamNG Rally 1.0​

BeamNG Rally has been created and published by Track Broseff on the BeamNG repository, and this mod breathes fresh new life into the title with custom rally stages on dirt and tarmac based on the real-world American Rally Association ruleset.

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BeamNG's rally pace notes

Over 88 miles/141 kilometres of rally stages are available, and all stages can also be run in reverse within the time trial menus. The maps range from Utah to Jungle Rock Island and everything in between. The real draw to this specific rally mod, however, is the inclusion of pace notes. A revolutionary addition that has put BeamNG on the map for rally fans.

Combine these essential rally additions with BeamNG's soft-body physics and you have a rally game that is as punishing and brutal as it can get in sim racing. Overall, it works brilliantly. The pace notes are mostly accurate with a few further additions that you will not see in any other games apart from Richard Burns Rally.

Should 'Realistic' Damage be the aim?​

But how about circuit racing? Often when the subject of damage models in sim racing is brought up, you will hear the take that the most realistic is the best. This is not always the case. Again, let's look at BeamNG. Your PC's required processing power to simulate your car is immense. Imagine trying to do that for twenty-plus cars simultaneously while also producing the driving physics and running an online server.

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Medium-speed wall impact damage in Automobilista 2

Most simulators skip a high-detail damage model in favour of a more immersive and detailed driving experience. This is not uncommon and is a tried and true method of creating an accurate racing simulation - it is the core of the experience, after all. Racing titles, especially pure simulators, should not entirely sacrifice their damage model; there is no question about it.

With that being said, accurately realistic damage should not be a priority for a lot of simulators. The relatively forgiving damage model of RaceRoom, for instance, could be considered a part of why the title can be run by lower-end PCs as well as forgiving small mistakes online, a key addition for teaching new players what is good and what is not without ending their race.

Which simulators do you think should include soft-body physics? Should it be kept to titles similar to BeamNG? Let us know in the comments below!
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Connor Minniss
Website Content Editor & Motorsport Photographer aiming to bring you the best of the best within the world of sim racing.

Comments

While it would be a bonus to have realistic race battle damage especially in rally or stock car racing, I would not want to have 100% accurate crumple zones, carbon fiber shards, etc., if the effort spent could be used for in other areas: enhanced vehicle sounds, optimized AI, accurate tire wear, realistic weather impacts, and properly deployed safety cars being among the other higher priorities. While dramatic, crashing is typically a short duration event and best avoided; why emphasize a few seconds of track/road time at the expense of typical hours behind the wheel?
 
I think the issue is most sims what you see has no physical properties and what has physical properties you don’t see in game.
Exactly my point :)
An example is ISI engined games (not picking on it, I just am most familiar with it compared to the rest). You have to enter in all sorts of "feeler" values in a text file for the vehicle contact to tell the car where it can bottom-out against the ground and all sorts of stuff like that. You can then also have cars get stuck in places they shouldn't. You can have parts of the car going through the surface of the ground. All sorts of ridiculous stuff depending on the numbers entered. None of this should be required.

The physical car should simply be in the game therefore the designed shape of the car on it's own will naturally dictate how it responds to contacting the ground, curbs, other cars, etc. All aspects of it's body, chassis, tyres, etc. would simply be physical properties along with the track. This does not require soft-body physics. The car should just naturally dictate on it's own the contact behavior. It should not be possible for a part of a vehicle to literally go through the ground or through another car - and it should have nothing to do with #s entered by a content-creator / modder, it should just simply not be possible at all because they're actual physical objects in-game that obviously cannot go through each other.
 
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Exactly my point :)
An example is ISI engined games (not picking on it, I just am most familiar with it compared to the rest). You have to enter in all sorts of "feeler" values in a text file for the vehicle contact to tell the car where it can bottom-out against the ground and all sorts of stuff like that. You can then also have cars get stuck in places they shouldn't. You can have parts of the car going through the surface of the ground. All sorts of ridiculous stuff depending on the numbers entered. None of this should be required.

The physical car should simply be in the game therefore the designed shape of the car on it's own will naturally dictate how it responds to contacting the ground, curbs, other cars, etc. All aspects of it's body, chassis, tyres, etc. would simply be physical properties along with the track. This does not require soft-body physics. The car should just naturally dictate on it's own the contact behavior. It should not be possible for a part of a vehicle to literally go through the ground or through another car - and it should have nothing to do with #s entered by a content-creator / modder, it should just simply not be possible at all because they're actual physical objects in-game that obviously cannot go through each other.
My experience is with AC and just tracks, never modeled a car. I think the issue with what you are suggesting is hardware limitations. FPS would be garbage on monitors, and forget about VR. Maybe in the distant future this would be possible, but in 2024 I don't think we are close to that, at this point.
 
Who's "we"?
I'm was talking about most sim racing games in general.

I can't imagine a racing game released in the last decades using "hit boxes"... it's really not a thing.

Most games use some kind of "proxi" collider mesh.. this is a simplified triangle mesh that follows the shape of the car pretty closely.

The reason you can't simply use the same high-poly model used for the graphics is that the collider shape has to be solved on the CPU and the CPUs performance advancements are not as exceptional as GPUs' advancements.

Car body to ground is particurarly performance hungry because the body is always very close to the ground so there's no way to discard the test like you can do with car vs car or car vs walls so it's basically running many triangle-triangle tests every physics tick.
 
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I can't imagine a racing game released in the last decades using "hit boxes"... it's really not a thing.

Most games use some kind of "proxi" collider mesh.. this is a simplified triangle mesh that follows the shape of the car pretty closely.

The reason you can't simply use the same high-poly model used for the graphics is that the collider shape has to be solved on the CPU and the CPUs performance advancements are not as exceptional as GPUs' advancements.

Car body to ground is particurarly performance hungry because the body is always very close to the ground so there's no way to discard the test like you can do with car vs car or car vs walls so it's basically running many triangle-triangle tests every physics tick.
Fascinating topic, thanks for your insights Stefano.
 
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"Most games use some kind of "proxi" collider mesh.. this is a simplified triangle mesh that follows the shape of the car pretty closely"

Exactly how my uninformed brain had envisioned a hit box being implemented in a modern racing game.
 
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"Most games use some kind of "proxi" collider mesh.. this is a simplified triangle mesh that follows the shape of the car pretty closely"

Exactly how my uninformed brain had envisioned a hit box being implemented in a modern racing game.
Yeah, what the Americans call a pavement we in the UK call a road and the pavement is the bit that goes along the side of the road for us to walk along...
Other examples of same thing different name are, bonnet/hood, wing/fender, trunk/boot and of course collider mesh and hit box;)
 
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Yeah, what the Americans call a pavement we in the UK call a road and the pavement is the bit that goes along the side of the road for us to walk along...
Other examples of same thing different name are, bonnet/hood, wing/fender, trunk/boot and of course collider mesh and hit box;)
Just a correction, in the US we don’t call a road, pavement, we call it a road. We call the paved bit on the side of the road a sidewalk. In PA anyway.
 
Premium
You mean the foot path?
A foot path would be a dirt trail or a paved walk on its own. But never beside a road. I am from a dairy country in PA and their is not many sidewalks along the road. That 1-2 foot section beside the road of asphalt and gravel is referred to as the road edge. We also say (a lu min um) not (alu mini um). :D
 

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