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Scawen
Developer
I don't have time to get into tyre physics at the moment but had some thoughts on it after Eeekie's post.

I think there are some competing effects when the throttle is applied.

1) As Eeekie described, the rear wheels become more loaded, lengthening the contact patch and so requiring less slip angle for a given lateral force. And conversely the front wheels become less loaded, get a shorter contact patch and require more slip angle for a given lateral force. From this point of view the car might take a wider line without any steering adjustment.

2) But there is another effect and that is that a wheel which has a longitudinal force applied, will produce less lateral force for a given slip angle. So from this point of view, a rear wheel drive car with more throttle applied (and no change in steering input) will follow a tighter line because the rear wheels will require a wider slip angle for a given force.

3) There are also other possible competing effects, such as the change in toe and camber due to suspension deflection, and the effect of a limited slip differential.

Now, I definitely may be wrong but I imagine number (2) above to be the dominant effect. I think that is how it is in my car but it would be hard to test unless I can find a skid pad. It may well be that a different effect is dominant in different cars, due to the different mass distributions and other design features. As I apply the throttle there is a whole range of slip angles before the point when the whole contact patch is skidding. Now I'm really not a crazy driver at all these days and don't drive much anyway but there are times when I can accelerate pretty hard out of a roundabout without any danger to myself or others. I can apply a lot of power without actually going sideways and it feels to me like it gets closer to oversteer through that process. It feels very planted and poised as I apply more power. A good part of my mind is focussed on the rear wheels, remembering I used to be a motorcyclist and am very aware of going over the limit. It's a feeling of confidence though and there is a certain joy to it. I believe I get this same feeling in the new physics of LFS, but in the old LFS there are some slight changes of line that don't seem to correspond with reality.
Scawen
Developer
We reported the copyright infringement about a week ago and it has now been removed.
Scawen
Developer
These are good questions but I'm not getting into tyre physics now.

I can't remember everything and will be starting with a good look into what we have and what is covered and what is not.
Scawen
Developer
Calculations and algorithms based on models and then the constants adjusted to try to match test rig data available for some tyres, and lateral force figures for some cars and just sometimes we can do lap time comparisons.

So in short - get a benchmark based on models and constants then adjust the constants according to as many real world results as possible.

In practice you can then find the models or assumptions are wrong or don't scale properly then you can read scientific papers on theory of rubber adhesion, etc. and try to figure out how to make sense of such complex phenomena described in seemingly abstract papers with confusing mathematics, into something that can really be implemented into realtime simulation with several cars at the same time. Smile
Scawen
Developer
Quote from DMN_ :good job! I can't wait to progress from the Fern Bay track.
Will a future update work fairly well with the integrated graphics card? I have intel hd 4000 and currently max 60 fps at the maximum graphics settings.

It is hard to know but I will try to allow enough settings to run OK on lower spec computers. For example shadow maps can be made quite a lot faster by reducing the number of cascades and the distance that can be rendered, and switch off shadows in mirrors. Also you can switch off HDR mode, reduce texture resolution etc.

Quote from Pathseeker :Awesome job Scawen! So initialy we might get new tyres with some mistakes, but then with some updates you will bring them to level you expect to reach? Or you think you will have enough time to make them to level you want with the update?
Also what we can expect performance wise from new tyres? Will initial grip level will be the same, or there will be quite diffirence?

I can't really release them as they are because you can exploit the issues. So I hope to make them a better approximation of reality so that they are fun to drive on and respond in realistic ways to changes in settings. As far as I remember, total grip was actually less but they feel better and more intuitive, so actually more fun to drive. One example, sometimes in the RWD cars, in the old physics, you can put on a little more power and the car seems to follow a wider line, which shouldn't really be the case when you add more longitudinal force to the rear tyres. In reality and in the new system, more power in a RWD car always results in the car taking a bit tighter line. This is because the combination of forces is now done in a way that makes more sense and has a mathematical basis. The public version is more like a made up force combination, adjusted to try to match reality.

Quote from BerdyGaming :One thing that might be an issue is viewing the track from the free cam if things are rendered based on the car location. Is there something I'm missing in the explanation?

The free view video is only a demonstration. That mode is activated by a special button available in the development version so I can check how the occlusion is working. The free view doesn't use occlusion data normally, and doesn't need it so much as it's only the one view and no mirrors.

Quote from Flotch :not yet Omg omg omg
It disturbs me a lot when I play a little in LFS and see the GPU temperature almost as it was idle whn I quit ... while other games like ACC are bringing it to 80°c Big grin

The fan can speed up quite a bit these days. The shadow maps, more complex shaders, higher resolution textures, more detailed models, HDR and bloom effect are definitely using more GPU power.
Scawen
Developer
Quote from super_gt :I apologize, good job.

No problem, I think it is a good question and this new video answers it. Smile

Quote from nacim :Speaking of mirrors, @Scawen, how do you handle shadows for mirrors and environement maps ?

If I'm seeing correctly, for mirrors, you are rendering another cascade (maybe using a bounding frustum of the 3 mirrors in order render shadows 1 time instead of 3) with a max distance of around 250m. This is nice, considering a lot of game just don't render shadow maps in secondary renders (environement maps, mirrors).
For environement map I can't see much in the current screenshots and videos Schwitz

In mirrors, yes, it uses a bounding frustum of all the visible mirrors to generate a shared set of shadow cascades. Actually it goes with full distance at the moment although this is probably wasteful and we could get a reasonable result with fewer cascades. But fewer cascades means some extra copies of the shaders because the shaders use a #define for number of cascades. Still, the mirror views are narrower so their shadow render seems to be quite fast.

In environment map at first I used no shadow maps, but there were some very bright areas that stuck out badly because they were really in shadow, but appeared brightly lit in the environment map. In the end I chose to render everything in the environment map as if it was in shadow. It was a better choice as the main visual function of the environment map is really to block out areas of the sky. The sky is so bright compared with most objects, it's quite rare that I notice the missing sunlight on some objects in the environment maps.

Quote from loopingz :My two cents from the steam stats:
https://store.steampowered.com/hwsurvey/
It looks like 95% runs DX11 capable GPU. That might be lower for lfs as it is a heaven for low spec pc racers, and I understand they would not like to be dropped off. But DX11 is pretty comon now!

Thanks. On further thought this morning I should probably keep DX10 support as a separate issue from SDR mode. For as long as it's easy, I might as well leave DX10 available but with certain features disabled. E.g. their cars would use the approximate diffuse lighting instead of calculating it from the environment map. But they could still use automatic exposure using the CPU method. I don't know how long DX10 support can last but think it is worth keeping it as long as it's easy to do so.
Scawen
Developer
OK, here is the same video from the in-car view.

The idea is you should not see any pop-up at all.

Scawen
Developer
Quote from Evolution_R :The other major thing was:
[graphics and physics on separate threads]

But I guess that is maybe after the graphics are done. Shrug

Yes this would be helpful for maintaining high frame rate as the CPU still has do do a lot of work asking the graphics card to draw things. So I will be thinking about this probably when I'm on the physics.

Quote from nacim :Wow, I'm really impressed by the ammount of work put into South City, good job !

@Scawen: You moved histogram generation on the GPU, that's nice to see, and looking at the settings that you got to tweak it, I feel like we saw similar papers for it. Smile
Did you had to move to feature level 11 for it or did you found a way to make it work in feature level 10.0 ? Uhmm

I did have to use 11 because InterlockedAdd was not allowed in feature level 10 and I couldn't think of another way to add to the histogram buffer.

Some possibilities here, the old 'read back a small texture and analyse on CPU' is still there for test purposes, so could be resurrected for Direct3D 10 GPUs. But I was thinking maybe feature level 10 could use the SDR mode and use time-based exposure instead. That would allow D3D10 graphics cards to use LFS but some things wouldn't be much good, e.g. it would be very dark in a car park.

But I don't know how many people have a Direct3D 10 graphics card as D3D10 was out a relatively short time before D3D11 was available. I think for now I'll keep trying to make sure it can run on them using SDR.

Quote from Aleksandr_124rus :Nice, but i remember there has problems with merging code of the two LFS builds, how progress is going on now of merging builds with tire physics and graphics, or it is done now?

The new tyre physics is in this new version. So the situation is that it might be a bit hard to try to copy the old tyre physics from the public version, into this new version. I am more motivated to try and update the new tyre physics to an acceptable level. It is nice to drive with but needs some good work on load sensitivity, pressure and temperatures which are not correct.

Quote from MagicFr :Always nice to see improvements in LFS Smile Well done.
my 2 cents for VR as a only-VR user. and having tested auto-exposure in iRacing.
It doesn't work well in VR as the whole view is taken by the game, opposite to when looking at a game on a monitor ( or triple ) that take only , maybe 25%, of your FOV.

Yes, I found in VR the exposure is calculated as dark if you use the whole view, because so much of the view is the car interior, so then it overexposed the image. So in LFS it limits the exposure check to a smaller square in each eye (both added together for a single exposure histogram). This limited square is 30 degrees each way, equivalent to a 60 degree FOV on a square monitor.
Scawen
Developer
Thank you for the feedback, pleased you like the progress so far.

I have a bit more to do on the graphics, though I want to spend some time on the physics soon.

A couple of urgent things I can think of.

- I want to convert the 'individual car diffuse lighting calculated from dynamic environment map' into a compute shader so I can use it for all the cars that have an environment map. More distant cars will use the 'approximate diffuse' lighting that is currently in the paths. That's only about a day or two's work, I think, as it's a simple compute shader (and a conversion of existing code).

- The approximate lighting, for more distant cars and will also be useful for temporary objects like physics objects, layout objects and skid marks. It always was stored in the paths. But now I think it can use the occlusion octree, as that already covers all driveable areas. This sounds like a few days work.

- One obvious thing is clouds in the sky but I really don't want skies to prevent work on the physics. In my mind this can be released without clouds, but cannot be released without the physics updates.

- Various things on paper lists here but I am actually crossing them off faster than adding them now.

On Eric's side there are still plenty of holes and gaps at South City, mainly because there are really a lot of new roads and connections and he has been filling those new places up with detailed buildings. Some more holes to fill at Kyoto, and there is Fern Bay too. So both of us will still be busy for quite a while.

Quote from Degats :Eric's been busy

Obligatory comparisons:

Thanks for the comparison shots!

Quote from kagurazakayukari :Wow! a lot of information!
Blow my mind XD

Again, had translated into Chinese~

Thank you for that! Smile
September Progress Report
Scawen
Developer
Hello Racers,

In our last report on the website we showed some images of the updated South City and demonstrated day to night transitions and night driving. Since then, Eric has continued to work on South City and Scawen has continued to develop the graphics system. We posted some intermediate progress reports on the forum.

In this report we will link to the intermediate reports, talk about more recent updates and show some new screenshots. The information is quite technical so if you aren't that interested in the internals of game development, feel free to skip straight to the screenshots which can hopefully speak for themselves!

September Progress Report

We hope you like the pictures and videos!
Scawen
Developer
Had to delete some posts which were taking the conversation in wrong directions.

We are working on LFS and it's going well.

We hope to do a progress report at the end of the month.
Scawen
Developer
You reached a point which is outside the map square system. The rectangle of map squares is set to the size big enough to include all the default ground that is set to have physical properties. Outside that, there are no map squares for your objects to be registered on.

The map squares system is designed to rapidly identify nearby objects to check for physical contacts during each frame's physics calculations.
Scawen
Developer
Wizard, I was trying not to waste time on it, because I have work to do.

The post was reported and is questionable. For me, it's questionable because it has a modified version of a Chinese flag and is something to do with Coronavirus. Why it has Winnie the Pooh, I really have no idea but it is questionable.

I don't want to spend a long time googling the association between Winnie the Pooh, the Chinese flag and Coronavirus. As a British person who was born in Hong Kong, I am concerned about the Chinese government's handling on Hong Kong but I don't see any reason not to respect the Chinese flag at this stage. All people from around the world are welcome in Live for Speed so I don't think modifying a flag and associating China with Coronavirus is the right thing to do in Live for Speed.

Maybe I've missed something but I had sat down to do some work and instead, I have to write a lengthy explanations about a simple moderation of something that seemed questionable to me.
June Progress Report
Scawen
Developer
Dear Racers,

In the March report I described how Live for Speed has been converted to use Direct3D 11. I've now started to use some of the features that Direct3D 11 allows.

Most interesting is the image-based automatic exposure. As we have moved to more physically based lighting, allowing day to night transitions and realistic brightness for artificial lights, there are many reasons why the exposure level needs to be adjusted. Not only for different times of day but also for the lighting conditions at any location. An extreme example is when you enter a multi-storey car park on a sunny day. The exposure level must adapt to what you can see, just as your eyes or a camera would do in reality. This is demonstrated in the video below. If you don't notice it happening too much then it's working well. Without the automatic exposure it would be very dark inside or totally overexposed outside.



On the technical side, a reduced copy of the output image (that has already been generated for the bloom effect) is transferred to memory that the CPU can read. Direct3D 11 allows this to be done without waiting. A histogram is constructed so the program can estimate the exposure level to use. The brightness is then adjusted to that target over several frames.

These car parks don't have a path with pre-generated lighting values or any light probe information (yet) so I added a system to allow the ambient lighting to be calculated in real time by analysing a copy of the car's unique environment map. In the video, this allows the car to be lit by the artificial lights and avoid being lit by the sky. It's probably not the best way to get the diffuse lighting in car parks but it is a good fallback when there is no data available.

Eric has continued working on South City. It's a longer process than any of us had imagined, because he has been updating most of the buildings with more detailed architecture and opening up new roads around the city. He doesn't want to show a lot of new areas yet because there are too many holes around but some night and day shots of similar scenes are attached below.

Other updates I wont try to cover in detail include some features to help Eric in the editors and completing the conversion to Direct3D 11. Support for Direct3D 9 has now been dropped as it was not reasonable for me to try to maintain the two versions. The GPU requirements are higher now so I wouldn't expect it to run well on a Direct3D 9 graphics card anyway.

We're getting there gradually. It's a lot of work on the programming side and the content side but we like the results!
Scawen
Developer
I'll close the thread now. Thumbs up
Scawen
Developer
Thanks, we have fixed a network error so old versions should work again now.
Scawen
Developer
Update: We have now fixed a network error, so the old versions should work again now.
Scawen
Developer
OK people, please be nice.

The thread title does not help but maybe something has changed. There is obviously a language issue here but we don't know unless we ask.

zamac2 - Please tell us exactly what you noticed. We have not intentionally made any changes to old versions. We have done some server maintenance and maybe that affected something.
Scawen
Developer
Quote from sermilan :If you want to buy LFS S2 for 17 GBP:

1. Buy this wheel
2. Throw it in the bin
3. Use the free S2 that comes along with it

I don't think that's true, don't remember any deal with a wheel maker and we don't do any such cheap deals as our licenses are for 'lifetime'.

Probably just an old copy of LFS on the cd? Uhmm
Scawen
Developer
Quote from BlakjeKaas :Are (and how are) PB's affected by this change?

This change is only about allowing something that already exists, to be discussed on our forum.

The only change would be that developers and moderators would accept certain threads and posts that have previously not been allowed.

It doesn't have anything to do with PBs as there would still be no official support for mods at this time.
Scawen
Developer
We did give permission for Blackwood to be ported to AC.

We like people to have fun (and don't mind if they use other sims) and as it's Demo content we didn't feel we would be losing out in any way. We gave the condition that LFS adverts should be visible in the ported version of Blackwood so we would get a little exposure.
Scawen
Developer
Thanks for the examples.
Scawen
Developer
Quote from BeNoM :All other games that have/allow mods don't care about licensing and copyright since it's not shipped with the game, why does it matter with LFS?

See: GTA V, rFactor, Assetto Corsa, Need For Speed, etc.

This is not about whether people can make mods for the game. It's about us hosting those mods or allowing our site to be used to advertise them. I'd be interested to see if there are official places where you can download mods for those games (excluding AC as their section was closed). I'm not interested to go searching for them at the moment as I have work to do, but if you could link to them that would be helpful.

As mentioned above, there are two problems.

1) People copying or converting vehicles made for other games then hosting or linking to them here. In that case LFS site can be seen to support copyright infringements. This cannot be allowed and would require strict moderation. This is one of the reasons given for closing the car mods section on Assetto Corsa.

2) People creating models of real cars. This is obviously fine for their own use but there may be questions here. Supposing we have cars made by various famous manufacturers listed on our site, either as forum threads or even in some kind of future in-game mods download system. There is a possibility this can be seen as us profiting from the names, reputation and IP of those companies. Or maybe it really is fine for users to create such content and upload it. We can't take the risk unless this is established.
Scawen
Developer
Thanks for the testing.

To my mind it is still possible that the bad collisions were related to lag and prediction causing excessive intersections rather than being related to VOB at all. As we know bad collisions can happen at any time between unmodified cars. It's true I could do a better job with that.

I understand you asked some people when you saw the collisions and often found out they were using VOB mods. But maybe these mods are just commonly used by people who go to cruise servers?
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