nomis3613
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Evolution of Gran Turismo Physics Modeling
Hi, I thought it would be interesting to go revisit the old games to see how the physics engine has evolved. So I fired up the old PS2 to compare GT3 and GT4 against the new kid on the block- GT5. Here’s my thoughts on each. I will take the same(ish) car to Laguna Seca in each game, run some laps, make some observations, get some lap times and do a basic test of the effect of spring rate tuning. All testing will be done with an RX-7 Spirit, but I will also check another car to make sure that my observations aren’t based on a quirk of the RX-7 (or its setup) in that game.
The parts used are all engine upgrades, full weight reduction, sports soft tyres, FC gearbox, FC LSD (but no other drivetrain parts), all brake upgrades.
Default settings will be used, except LSD will be initial 5, accel 20, decel 5. My lap times will all be slow (cos I’m a bad driver
), but they are here for comparison. Also, my thumbs are used to GT5 at the moment, so I won’t be getting the best out of GT3 or GT4 because I’m out of practice with their subtleties. All of this stuff is just my opinion of course, I'll just skip the "IMHO" at the start of each sentence to make it easier to read.
Gran Turismo 3
RX-7 RZ (no Spirit in GT3): 655 bhp, 1079 kg, racing super hard tyres (no sports hard in GT3)
Laguna lap: 1:26
Effect of stiffer front spring: possibly more understeer, but hard to tell because it’s masked by power oversteer
Effect of stiffer rear spring: more oversteer
COMMENTS ON PHYSICS
- no body movement at all (roll, pitch or dive)
- possible that traction for each rear wheel is not calculated separately, they always seem to lose traction together (although this may be the LSD setting)
- very drift-friendly in general. Just get on the gas and the rear end gently arcs around (feeling more like a gently swinging rear while trying to turn and brake than a realistic “stepping out” due to torque). As long as you can countersteer enough to not spin, there is very little speed lost with Tokyo Drift style driving.
- no power understeer for RWD. It's very simple in GT3: throttle = oversteer
- no “recovery" needed from drifting. So you can come in sideways and quickly power out. This makes it very forgiving for coming into a corner too hot- you just slide it in sideways to wash off speed without much loss in lap time
- instant turn-in (eg no delay for the car to transfer load to the outside tyre), makes the car feel very twitchy compared to GT5, feels like the car is wandering due to excessive toe at high speed
- engine revs don’t flare with lost traction. Wheelspin seems to be just the engine holds a set RPM while the wheel speed catches up.
Gran Tusimo 4
RX-7 Spirit: 611 bhp, 1079 kg, sports hard tyres
Laguna lap: 1:33
Effect of stiffer front spring: perhaps sharper turn-in, definitely not a simple increase in understeer like textbook theory says though
Effect of stiffer rear spring: seems like traction a bit worse, no noticeable increase in oversteer otherwise
COMMENTS ON PHYSICS
- body movement now present
- like GT3, the turn-in is instant
- very unstable during transients, I suspect therefore there is greater effect of damper tuning than in GT5
- no longer just “floats” over kerbs and grass. You actually have to consider that the bumps may jolt you off the intended line
- drifting hurts lap times more than GT3, seems that reduced grip when sliding is now modeled. Also it is easier to spin when drifting
- accelerating reduces front grip, so in RWD there is now a balance of power oversteer vs “nose lift” understeer
- turn up the front brake strength too high and you can hear the tyres chatter under ABS
- revs flare over bumps, unlike GT3
Gran Tusimo 5
RX-7 Spirit: 433 bhp, 1051 kg, sports hard tyres
Laguna lap: 1:32
Effect of stiffer front spring: sharper turn-in, definitely not a simple increase in understeer like textbook theory says though
Effect of stiffer rear spring: seems like traction a bit worse, perhaps slight increase in oversteer
COMMENTS ON PHYSICS
- LSD Accel has huge effect on corner exit behaviour for RWD cars. High values which cause the outside tyre to go red can greatly reduce exit understeer (as if torque vectoring). Aside from this, the "stepping out" of the rear under power seems much more realistic.
- turn-in no longer instant, so it's a lot smoother (perhaps the outside tyre needs to get some weight transfer before it delivers full turn-in)
- transients feel less unstable than GT4 (even with minimal damping)
- enter a corner too hot and you will understeer (in GT4 you could slide out backwards when coming in too fast)
- easier to upset grip levels mid-corner, such as with lateral weight transfer or throttle/steering/brake inputs. Smoothness is rewarded more in GT5.
- weight transfer has a greater effect on each tyre's grip
- why have GT4‘s drag testing and skidpad been removed?? (sorry, I couldn’t help myself!). The data analyser is far less useful without numbers
, and while NOS can be silly, it was sometimes useful in tuning (testing traction and allowing you to catch up with your ghost)
- the PS3 controller's analogue L2 and R2 buttons, so now controller users can “left foot” brake. However the sensitivity of these is terrible for the accelerator (brake is ok, because the ABS means it doesn't matter)
- ABS chattering of GT4 is gone. ABS is (unrealistically) excellent, it allows decent turning under full braking
- handling between different cars much more varied than previous games. Somehow the handling differences seem more fundamental, makes GT4 feel like all cars are a variation on the same theme.
General Comments
Looking back, GT3's physics now seem very "arcadey". But to the non-hardcore tuning elite(!) the game might be actually more fun than GT5. The simplicity of the physics and tuning, as well as the ease of holding fully hectic drift angles probably have great appeal to anyone who isn't a racing fanboy like us! As Gran Turismo's physics evolve to get more realistic (therefore difficult), PD could do worse than add an "arcade physics" option which brings back GT3 style simplicity. If only we could also have GT3's loading times back, too!!
Although I only had a very quick look at the effect of suspension settings, it seems that the often-cited theory of "stiffer rear increases oversteer, stiffer front increases understeer" was left behind after GT3. It feels like there are more complicated dynamics at play in GT4 and GT5.
GT4 moved the series away from "slot car racer" handling. Gamers now had to experience pitching and rolling (although many didn't like the feeling so just set the suspension rock hard!), but the effect of this body movement on actual grip levels was not present. Arguably, GT4 offers tuners the most tools for analysing their setup.
As a simulation, GT5 has some great improvements over GT4. The LSD and ABS modeling seem unrealistic, but there are some great improvements in the weight transfer mechanics and there is greater difference in the feel of different types of cars.
How do you think the physics has evolved? Also, if anyone could fire up GT1 or GT2, that'd be great cos I don't have them any more.
Hi, I thought it would be interesting to go revisit the old games to see how the physics engine has evolved. So I fired up the old PS2 to compare GT3 and GT4 against the new kid on the block- GT5. Here’s my thoughts on each. I will take the same(ish) car to Laguna Seca in each game, run some laps, make some observations, get some lap times and do a basic test of the effect of spring rate tuning. All testing will be done with an RX-7 Spirit, but I will also check another car to make sure that my observations aren’t based on a quirk of the RX-7 (or its setup) in that game.
The parts used are all engine upgrades, full weight reduction, sports soft tyres, FC gearbox, FC LSD (but no other drivetrain parts), all brake upgrades.
Default settings will be used, except LSD will be initial 5, accel 20, decel 5. My lap times will all be slow (cos I’m a bad driver
), but they are here for comparison. Also, my thumbs are used to GT5 at the moment, so I won’t be getting the best out of GT3 or GT4 because I’m out of practice with their subtleties. All of this stuff is just my opinion of course, I'll just skip the "IMHO" at the start of each sentence to make it easier to read.Gran Turismo 3
RX-7 RZ (no Spirit in GT3): 655 bhp, 1079 kg, racing super hard tyres (no sports hard in GT3)
Laguna lap: 1:26
Effect of stiffer front spring: possibly more understeer, but hard to tell because it’s masked by power oversteer
Effect of stiffer rear spring: more oversteer
COMMENTS ON PHYSICS
- no body movement at all (roll, pitch or dive)
- possible that traction for each rear wheel is not calculated separately, they always seem to lose traction together (although this may be the LSD setting)
- very drift-friendly in general. Just get on the gas and the rear end gently arcs around (feeling more like a gently swinging rear while trying to turn and brake than a realistic “stepping out” due to torque). As long as you can countersteer enough to not spin, there is very little speed lost with Tokyo Drift style driving.
- no power understeer for RWD. It's very simple in GT3: throttle = oversteer
- no “recovery" needed from drifting. So you can come in sideways and quickly power out. This makes it very forgiving for coming into a corner too hot- you just slide it in sideways to wash off speed without much loss in lap time
- instant turn-in (eg no delay for the car to transfer load to the outside tyre), makes the car feel very twitchy compared to GT5, feels like the car is wandering due to excessive toe at high speed
- engine revs don’t flare with lost traction. Wheelspin seems to be just the engine holds a set RPM while the wheel speed catches up.
Gran Tusimo 4
RX-7 Spirit: 611 bhp, 1079 kg, sports hard tyres
Laguna lap: 1:33
Effect of stiffer front spring: perhaps sharper turn-in, definitely not a simple increase in understeer like textbook theory says though
Effect of stiffer rear spring: seems like traction a bit worse, no noticeable increase in oversteer otherwise
COMMENTS ON PHYSICS
- body movement now present
- like GT3, the turn-in is instant
- very unstable during transients, I suspect therefore there is greater effect of damper tuning than in GT5
- no longer just “floats” over kerbs and grass. You actually have to consider that the bumps may jolt you off the intended line
- drifting hurts lap times more than GT3, seems that reduced grip when sliding is now modeled. Also it is easier to spin when drifting
- accelerating reduces front grip, so in RWD there is now a balance of power oversteer vs “nose lift” understeer
- turn up the front brake strength too high and you can hear the tyres chatter under ABS
- revs flare over bumps, unlike GT3
Gran Tusimo 5
RX-7 Spirit: 433 bhp, 1051 kg, sports hard tyres
Laguna lap: 1:32
Effect of stiffer front spring: sharper turn-in, definitely not a simple increase in understeer like textbook theory says though
Effect of stiffer rear spring: seems like traction a bit worse, perhaps slight increase in oversteer
COMMENTS ON PHYSICS
- LSD Accel has huge effect on corner exit behaviour for RWD cars. High values which cause the outside tyre to go red can greatly reduce exit understeer (as if torque vectoring). Aside from this, the "stepping out" of the rear under power seems much more realistic.
- turn-in no longer instant, so it's a lot smoother (perhaps the outside tyre needs to get some weight transfer before it delivers full turn-in)
- transients feel less unstable than GT4 (even with minimal damping)
- enter a corner too hot and you will understeer (in GT4 you could slide out backwards when coming in too fast)
- easier to upset grip levels mid-corner, such as with lateral weight transfer or throttle/steering/brake inputs. Smoothness is rewarded more in GT5.
- weight transfer has a greater effect on each tyre's grip
- why have GT4‘s drag testing and skidpad been removed?? (sorry, I couldn’t help myself!). The data analyser is far less useful without numbers
, and while NOS can be silly, it was sometimes useful in tuning (testing traction and allowing you to catch up with your ghost)- the PS3 controller's analogue L2 and R2 buttons, so now controller users can “left foot” brake. However the sensitivity of these is terrible for the accelerator (brake is ok, because the ABS means it doesn't matter)
- ABS chattering of GT4 is gone. ABS is (unrealistically) excellent, it allows decent turning under full braking
- handling between different cars much more varied than previous games. Somehow the handling differences seem more fundamental, makes GT4 feel like all cars are a variation on the same theme.
General Comments
Looking back, GT3's physics now seem very "arcadey". But to the non-hardcore tuning elite(!) the game might be actually more fun than GT5. The simplicity of the physics and tuning, as well as the ease of holding fully hectic drift angles probably have great appeal to anyone who isn't a racing fanboy like us! As Gran Turismo's physics evolve to get more realistic (therefore difficult), PD could do worse than add an "arcade physics" option which brings back GT3 style simplicity. If only we could also have GT3's loading times back, too!!
Although I only had a very quick look at the effect of suspension settings, it seems that the often-cited theory of "stiffer rear increases oversteer, stiffer front increases understeer" was left behind after GT3. It feels like there are more complicated dynamics at play in GT4 and GT5.
GT4 moved the series away from "slot car racer" handling. Gamers now had to experience pitching and rolling (although many didn't like the feeling so just set the suspension rock hard!), but the effect of this body movement on actual grip levels was not present. Arguably, GT4 offers tuners the most tools for analysing their setup.
As a simulation, GT5 has some great improvements over GT4. The LSD and ABS modeling seem unrealistic, but there are some great improvements in the weight transfer mechanics and there is greater difference in the feel of different types of cars.
How do you think the physics has evolved? Also, if anyone could fire up GT1 or GT2, that'd be great cos I don't have them any more.
