Rfactor2 Chassis flex?

Discussion in 'General Discussion' started by Skynet, Sep 13, 2012.

  1. Skynet

    Skynet Registered

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  2. Niels_at_home

    Niels_at_home Registered

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    Chassis flex is one of those things that gets mentioned too often. For modern well made racing cars its not a really important factor, that is compared to tires and a few other things. Older less well made cars may have more chassis flex, but also softer suspension, which again makes the chassis flex less big a deal.
     
  3. Nimugp

    Nimugp Registered

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    This may indeed be right, no idea how it goes for racecars. For Go-Karts however it is really important ;) (at least IRL)
     
  4. Slimjim

    Slimjim Registered

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    what your seeing in the video is not chassis flex, the cam is mounted on the sidepod, and it's moving up and down, if it was mounted on the chassis you would see no movement, other than the driver fairing bouncing up and down. the axle does more flexing than the chassis.
    a mesh is a solid object, and the only way you could see it bend would be with animation..
    plus what you see or think is a chassis flexing when lifting the rear tire on tight corners is more to do with the geometry of the chassis and suspension.
    if a kart front tires had normal pivot points, the same as a car, a kart would not jack / lift the inside tire.
    this is also caused by the amount of caster a kart has, raising one side while lowering the other side..
    it's makes it kind of like a table with uneven legs, rocking on 2 points... i have this effect now in rF1, just started working on rF2.
     
  5. Spinelli

    Spinelli Banned

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    Slimjim, that game does have chassis flex modelled. I have been following it for some time. Its not fully modelled into the graphics yet ( like how RFactor 2 physics arent fully modelled into graphics), but the sim does simulate it, you can actually see some going on in that video.

    Some guyhad this to say on youtube

    "fairly sure the bars infront of the fuel tank (under the wheel holding up the steering column) do not bend and twist that much!"

    Then the guy replied:

    "You're right about the bars not bending that much. The physics model also doesn't bend as much as this; however the number of elements that are calculated in the model is exponentially larger than what can represent graphically in realtime. Hence there's a tradeoff between what you see and what the physics model is doing, as we can only sample it in a few locations. We'll be covering this in detail during the next developer blog. Keep in mind the footage is Pre-Alpha, and it will improve"



    Also, as someone else in page 1 mentioned, I read the same thing, that Rigs of Rods, although it may look fabulous to a bunch of people watching/playing, it is actually very in-accurate and would fail horribly in a sim, especially a hardcore racing sim.
     
  6. Slimjim

    Slimjim Registered

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  7. Spinelli

    Spinelli Banned

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    Looks great man awesome job, i hope it becomes more violent though not only in terms of the visual feel, but also in terms of the massive twitchyness and constant constant micro corrections that real karts have
     
  8. Slimjim

    Slimjim Registered

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    oh it's pretty violent with the FFB, it's the 1st day testing everything,
    getting the kart and track into the game, trying to learn how to sort out the textures, then physics on top of that. makes for a long day...lol
    It feels better in rF1, but i'm still learning what the new .TGM file is doing.
    this really throws a wrench into everything, but to be honest, the more i drive in rF2, the less i like the lighting,
    seems a bit on the dark side, will be having a good look at Assetto Corsa before i make a decision of where i'll be modding.
     
  9. jtbo

    jtbo Registered

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    Play with these, I know there is probably some scientific way of getting proper values, but it might take time to find out what it is, so as I messaged Niels, these seem to affect mostly how tire behaves, especially when overdriving it and I have found these having more effect than tire's geometry to when tire is loosing the grip game.

    Code:
    StaticCurve=(153, 0.61, 353, 1.176, 653, 0.61) // at -100C there's 60% of maximum static grip, at 100C it's maximum, at 400C it's back down to 60% of max static grip
    SlidingAdhesionCurve=(-9.2, 0.4, -5.2, 1.7, -1.2, 0.2)
    SlidingMicroDeformationCurve=(-5.2, 0.3, -1.2, 1.8, +1.8, 0.3)
    SlidingMacroDeformationCurve=(-1.2, 0.2, +1.8, 2.0, +4.8, 0.4)
    For example, if you would like to remove heat effects to grip, then you set static curve to 1.0 for all temps, three others are then how road surface is affecting sliding tire, adhesion affects also how tire wears, micro and macro effects are for different surface texture, which again is possible to set in track file I believe, but haven't checked.

    As static curve was temp, setting, temp, setting... other curves had similar way, every other setting, every other condition, now I forgot if that was velocity or slip or what again, need to read it again.

    Those are however important bits in jungle of parameters. Of course general grip level settings, at top of realtime section.

    I still don't know good way to temp bristle spring 1st and 3rd parameter, but 2nd one is told in tire manual and those have quite bit of effect to tire's behavior, haven't really managed to find too large difference with two bit different geometry, those other parameters seem to have larger effect, but there is quite lot to learn for me still.
     
  10. Gearjammer

    Gearjammer Registered

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    Jim, are you using HDR lighting? If you are try without and see if the lighting is better or vice versa.
     
  11. Slimjim

    Slimjim Registered

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    the video was done without HDR enabled, the HDR just makes it darker...lol

    and Thanks for the tips on the TGM file...
    anyone know how to use this in-game TGM ttool.? I try to open a TGM file with it, and it crashes.
    I really would like to create my own, I'm using the one from the E-kart now to get the proper size.
    also.. i have noticed when i drive the kart tires look fine, but when the AI drives, the tread center of the tire is smaller than the sidewalls of the tire... lol
     
  12. Gearjammer

    Gearjammer Registered

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    So you are talking about the kart itself looking darker, and not the whole scene. That is interesting. For your skins on your karts, what format did you use for saving the DDS files, DXT5 or DXT1 or something else? Also, have you done anything with the skins for your driver? I am thinking it is possible that the driver skins are the issue as they are normally seen from inside the cockpit or at least under a tin top.
     
  13. Slimjim

    Slimjim Registered

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    no not the vehicle, the lighting in the game..
     
  14. Marvin Morgan

    Marvin Morgan Registered

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    Ok, I've been through this thread a few times, a topic I've been interested in for years. But I have to know, what the hell is a "sawn"? lol
     
  15. jubuttib

    jubuttib Registered

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    sawn past participle of saw (Verb)Verb:
    Cut (something, esp. wood or a tree) using a saw.
    Make or form (something) using a saw.

    EDIT: Incidentally I took a look at the page and it looked fine to me, totally unsawn. Either ISI fixed it fast or jtbo needs a new saw.
     
  16. jtbo

    jtbo Registered

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    My guess is that you did not type filename into box next to load button?

    If you check out modding dowloads sticky thread, there is tire quide v2, that explains it better than I ever can, but you need Ptool folder, or was it ptool, anyway there you put your tgm, then you can copy paste file name to tire tool with ctrl-c and ctrl-v, after that it should load.

    Editing is done to files with notepad++ or similar, that tool is only useful for testing and computing that big table at end of tgm file.

    When creating tires, I usually reduce DT multiplier to around 0.85, slows down computing but with default value it gets stuck always for me.

    Anyway, without reading that quick start guide it is fairly difficult to get on editing, I had to do few times all things told in that document to really understand anything.

    I have wrote lengthy posts to this thread that might shed some more light to things, or not, they contain too many words and too few pictures for anyone to be able to read them, but if you start working on tires and look for step you are doing, those might save headache or two.
    http://isiforums.net/f/showthread.php/2796-The-tgm-and-ttool/page7

    Whole thread is worth to scan trough as it probably contains most of the stuff you will need to get started, even it has more questions than answers, but some day we find answers and we can perhaps even understand things enough well to write them up to wiki so next guy don't need to invent wheel all over again.




    Seen, sawn, sea, saw, seen, been, what is really different sounds same to me :p
     
  17. Slimjim

    Slimjim Registered

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    yeah, I had my damn pTools folder in the Documents/rFactor2, so i moved it to the main rF2 folder in the programs. now it works.
    But man i'm going to need to have a refresher course on rocket science, then touch up on my brain surgery.
    props to the person that can understand all this stuff. i may have to team up with NASA to figure this one.

    i'm also scratchin my head over how to apply the rF2 shaders to get the proper reflections. but maybe one day it will come.
     
  18. jtbo

    jtbo Registered

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    For reflections, I believe you may find some answers from this thread, or then not, but it has good example by K S:
    http://isiforums.net/f/showthread.php/7691-Normals-which-way

    I have found that with aerodynamics, basic understanding of how it works is easier to achieve than with tires, first is part of the rocket science, latter is not, so maybe we have something that is more difficult than rocket science? :D

    You might need to have a play with this too as your Karts are so light, but I'm not quite sure yet, I understand that this defines rubber as material in how much it's grip changes from added pressurre, that is weight, I think all ISI cars are using same parameter though, so not quite sure if even Kart tires are really going to do much of difference to that, can't remember seeing much better information from this.
    RubberPressureSensitivityPower=(-0.075,5000,500000,1) // power,offset,nominal_max,normalize

    Remember that tire tool is just thing that computes tires for you based on geometry you have made to tgm file with notepad++, realtime section is then something you can alter without the tool, same goes for last two parameters of tire geometry lines (those sections that start with nodeXX), those last two are heating properties of material and can be changed without changing model.

    What is important is to know tire deflection to all three directions, so when turning how much tire's contact patch will move sideways, when tire has load of known value, how much it bulges, then when turning wheel with known power how much there is twist, knowing amounts of those deformations allow you to test with tire tool what kind of forces are required to have such amount of deformation and with that you can evaluate your tire's construction and also you get bristle spring values. (in manual there is description how to get value for vertical component, that is middle parameter of bristle spring).

    Difficult part is to find out how much real tire does deforming and at what kind of forces are required, so it requires quite bit of testing and evaluating to find out proper values, luckily it does not take half a day to do those testings, but you can do those testings only after you have done that half day computing part with automatic option that is at the bottom, I need always resize toolbox from top and then lift it bit up to get all options to be seen.

    At first it is quite a shock with all kinds of bells and whistles there, but if you take just small part first and then learn that small part, soon you will know your way around a tool and know what there is relevant and what is not for the current task, then it is not that much difficult to use the tool, it is much more difficult to find all the data and find out what and how to input into tgm file with notepad++.

    So far I have managed to end up only with tires that produce either too much grip to all directions except when accelerating, or tires that produce too little grip except for braking where it is way too much, so I guess that is slowly improving, but as I'm trying to create 70's street tires it is not something ISI has had in mind or when they have created tires for other cars so there is not much of example and I'm flying mostly blind, but I hope some day I have that figured out how to get them perfect.

    Tool itself is however easy part ;)
     

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