Difference of tire diameters between .tbc and .tgm tires in game

Discussion in 'Bug Reports' started by mantasisg, Dec 30, 2020.

  1. mantasisg

    mantasisg Registered

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    I am not sure, and confused, but I am suspecting there might be a bug regarding tire radius, especially if front and rear tires have very different diameters.

    An example:

    Player real time - .tgm
    [​IMG]

    AI controlled real time - .tbc
    [​IMG]
    I checked physics parameters of this car, and .tbc radius values are pretty much exact to furthest .tgm geometry node in y axis.

    Front tires shrink less, and rear tires shrink more when turning from tbc to tgm. I am working on one project, where cars has similar sizes front vs rear, and there is same effect, but base tgm is from different car origin, not Gasiline Alley.

    As a side effect this also affects rideheights. At least graphically it certainly does, not sure if it does affect it physically too, just as well not sure if tire gets affected physically too or if in physics it is all correct.
     
    Last edited: Dec 30, 2020
  2. Lazza

    Lazza Registered

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    Did you factor in the TGM sizemult?
     
  3. mantasisg

    mantasisg Registered

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    The tires I have business with now has SizeMultiplier=(1, 1). And I just looked at G.A. tgm, and interestingly rear tires are (1.3125,1.072495), which I guess means that with it on 1 and 1 rear tire would appear even smaller, possibly about same size as front, just like it does with mine tires (front shrinks a little, and rear shrinks to possibly same size as front).

    I have read that this size multiplier should be used only for minor adjustments, 1.31 or 31percent increase I'd say isn't minor. 7percent is not that little as well.

    In the tgm documentation of July 2013:
    SizeMultiplier = A multiplier to the geometrical width, and radius. Recommended to use only as a temporary solution or for very minor geometrical corrections. The default size information is contained within the [Node](s) and the [LookupData] section contains data about how those change due to various conditions such as rotation speeds.
     
  4. Bozak

    Bozak Registered

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    Hi mantasisg
    Have you checked AI (tbc) top speed vs human (tgm) if it's the same or very close?
    From the pics AI rear tires look smaller so should have less top speed.
    In order to fix the change of tire size between human-AI (tgm-tbc) adjust the radius at tbc.
    When you much visually the tire size then AI will have same top speed as human.
    I think the 3d tire.gmt diameter have to much of tgm.
     
  5. mantasisg

    mantasisg Registered

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    @Bozak Hey thanks for pointing it out. Looks like I have mixed up AI vs player images. Just fixed that. AI actually has bigger rear tires, that command tab probably confused me. But it is good suggestion to test top speeds, I will do it tomorrow at Le Grand Circuit.

    Speaking of adjusting tire sizes for a fix. I have decided to set .tbc sizes to be pretty much same as fronts, so when game loads car with tbc tires initially, the rideheights wouldn't get lowered as tire radius shrinks when switching to .tgm.

    In case if tgm tires would be smaller that tbc, rideheights would increase by switching to bigger radius .tgm. So it is not great as well. best would be to have same geometries in both .tbc and .tgm cases.

    I suppose in my case I could use "SizeMultiplier" in tgm, but I don't want to, as it is adviced to be used just for minor changes and temporarily.
     
  6. Lazza

    Lazza Registered

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    @mantasisg the TBC and TGM sizes have to match, or you will start getting strange behaviour. So if the TGM is the right size, adjust the TBC to match. If the TBC is right, rebuild the TGM or use the size Mult - I know what that line says, but you can have quite big changes without any major effect.

    If they match but look different, it might be a graphical thing in which case I can't help.
     
  7. mantasisg

    mantasisg Registered

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    Now I have tbc and tgm mismatch in order to keep rideheight as it is set in hdv, and I think the behaviour of the cars is not bad, and not strange.

    And my whole issue is that tgm is right size, but it does not load right size in game. So I have to tweak tbc in such way that it is similar to how game loads tgm, so the rideheights does not get messed up, which is especially an issue with much different front and rear sized wheels.

    And it shows to be the same with Gasoline Alley mod, so I assume there could be a bug.

    I might try as well increasing tgm sizemult way, just to see how car works then.

    And I checked the car I work with in 3Dsimed and opened up fbx in blender, and model wheel sizes and scales seemed to be correct.
     

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