GT - Game/physics engine discussion

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Famine

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So, I've been playing GT for a while now. Though the assets clearly share a lot with GT4 with the occasional addition (some new cars, Valencia GP track) and omission (loss of some "special" cars, Route 5 tracks) it has struck me that very little remains insofar as what happens on track now.

This thread exists to discuss these particular differences and possible implications for what drives GT5 while you drive (no, not Xzibit).

Things that I have noticed so far:

Understeer - reduced
A well-known Achilles' heel of GT4's physics was a tendency to exaggerate understeer. It wasn't quite so OTT as many people seem to think - the natural bias of almost every road car is understeer, and the natural reaction to attempting to turn into a corner too fast is understeer (with people failing to take account of this and without any inertial reference) - but the game was prone to power-on understeer even in very powerful RWD cars and almost everything wore its front tyres faster.

A great example of this was the Cizeta V16T, which was possibly the most useless of the supercars in GT4, given to just driving straight on at the slightest hint of a corner despite having no weight at all at the front. Now in GT it's a great car to drive and the AI uses it to great effect. It's by no means a demon in the corners - it's 90s tech with a transverse V16 in the back and wider than Spain - but it doesn't just give up and go straight on.

Oversteer - enhanced
I think that, as a by-product of the above, it's now easier to get the rear wheels to spin up with careless application of power. I never had much of an issue with this in GT4, save for the low speed stuff, but the removal of the power-on understeer that shouldn't have been there has changed this for the better.

AI - enhanced
On Level D, the AI are as dumb as a hat full of water and as predictable as night - GT4 level stuff. But on higher ranks they seem to be a combination of smarter and more fallible. I've seen them take each other on outbraking for a corner (one failed spectacularly - dipping a wheel onto the grass and going clean past the corner backwards) and, more impressively, try to break or maintain a draft. I've tested them several times on this - they will weave about on Level A to stop you keeping in a draft, or follow you if you do the same. Except, oddly, on Test Course where we all recognise that two cars go faster than one...

They're still prone to doing stupid things, but only if you do them too. Park on the apex or a corner and you're probably going to get clattered. Yet park on a straight and they'll at least try to dodge you (this can also be seen in GT5P).

Dirty tyres
I've tried this again and again and again. If you go through grass/sand, though it isn't visible, the game treats your tyres as if you've picked some crud up for at least the next few hundred yards. The car becomes all squirrely and slippy until, presumably through some arbitrary criteria, you're determined to have cleaned the tyres.


Now, I'm still just playing through rather than testing the physics and AI out, but these things are really quite apparent - some are even improvements over GT5P... However, they're also tempered by the fact that your only control is some digital buttons and maybe an analogue nipple for steering if you're so inclined.

So. Go ahead. Discuss. Have you noticed any other alterations to the game engine? Have you noticed these ones? Do you think I'm talking heffalump poop?
 
Agrees on most of them. I don't know about the dirty tyres. I try to stay on the road. :)

I have test that with the dirty tyres.
 
I agree with everything from what I have so far seen.

I will add some stuff I have witnessed:

AI
-Dust obscures their vision on dirt tracks. If anyone has been caught close behind the competition on a dirt track it can be very hard to see your upcoming apex. While in the lead I have multiple times seen the AI in my rear view mirror miss an apex and hit a wall with no outside interference, such as other AI bumping them. When I switched to rear view I saw that my dust trail had completely hidden the corner apex. It is the only thing I can attribute to their mistake.

-Collision avoidance. For some fun replays and photos I would go backward on courses to hit the AI head on in GT4. Usually it was just a matter of lining up to their line and hitting them head on. Here I had to try it twice because they swerved around me. I could only pull it off if I swerved at them unexpectedly within a second of impact.

I have also seen them swerve away from me when I take the inside line if I get my bumper even with the side front windows, but bump me and then pull away if I am behind that point. I'm unsure if it is replicating them being able to see me (past their blind spot) or me legally having the line at that point.

Dirty tires
-Dirt tracks w/tarmac sections. On tracks such as Tahiti Maze and Cathedral Rocks I have noticed that when I go from the dirt to the tarmac sections my traction seems reduced for a space but then grips better.

Collisions
-Rarely ever airborne. In GT4 on high speed sections, such as Test Track, if you hit the wall at a sharp angle on purpose or by accident your car would pop up into the air to the point that with proper photomode camera angles I could make it look like my car was flying. At ~230 mph in both a Veyron and the Pescarolo Hybride C60 they just hit the wall and had significant speed reduction (The Pescarolo actually stopped head on into the wall, tires spinning once) with just a tiny bounce or they would begin an uncontrollable spin.

Hitting the AI head on, as described earlier, also resulted in very little flying through the air.
 
I agree with everything said by Famine... Also Foolkiller's points are spot on... So I have not much to add... I am very happy though, that the AI atleast has SOME intelligence now and you can actually have some good side by side battles going into corners and such... Lets hope this carries over to GT5.... it will make the whole experience a lot more interesting... 👍
 
I thought the increased oversteer was just my lack of practice with the digital throttle.

I sometimes have what seems like massive understeer but I think it is because of the difficulty I have using the D pad for steering. It seems that to get the car to go full lock you have to repeatedly tap in the desired direction. If you just press it once it only seems to go so far. This could be because of something wrong with my PSP so I don't know if this is a valid in describing the physics of the game.

I have noticed the better AI, but once on the straight on La Sarthe a Lancia Stratos side swiped me as he went past. I thought it was unusual and maybe I caused it until he did it again on the next lap. The AI seems to use the draft a lot better than before, much to my dismay since I can't change the gearing to outrun them on the straight at La Sarthe or the Nurburgring. Then again the RBE would probably negate any advantage anyway.
 
Gravel Traps- In GT4 you could skip across gravel traps like a little girl in a garden. But now, the wheels actually sink into the gravel, and you lose a lot more speed, so you're better off not cutting the corner.
 
I thought the increased oversteer was just my lack of practice with the digital throttle.

I sometimes have what seems like massive understeer but I think it is because of the difficulty I have using the D pad for steering. It seems that to get the car to go full lock you have to repeatedly tap in the desired direction. If you just press it once it only seems to go so far. This could be because of something wrong with my PSP so I don't know if this is a valid in describing the physics of the game.

Ah, now something I've noticed with at least the brakes and accelerator is that there's effectively "input damping" - mash it into the housing and it'll go all the way to maximum, but it takes a couple of tenths to get there. Perhaps there's something similar happening with the steering?
 
Indeed there is. If you drive the F2007, you see that the wheels don't completely lock instantly, it takes a bit of time.
 
The automatic transmission is actually COMPETITIVE now. I noticed in GT4 that it was utterly dumb and wouldn't shift at the right points. But now it seems to actually know when to shift. Which is rather awesome for me.
 
Ah, now something I've noticed with at least the brakes and accelerator is that there's effectively "input damping" - mash it into the housing and it'll go all the way to maximum, but it takes a couple of tenths to get there. Perhaps there's something similar happening with the steering?


There is steering assist, but not dampening as there is with the Gas/Brake. Its much easier to test this with a DS3. At a stop if you push the D-pad control & hold it it will go to steering lock, one would HOPE the speed its completed in is dependent on how fast it can be done in the real car, but it will turn less depending on Speed, the slower you go the more she will turn. The Nubb however will give you the ability to maintain a corner smoothly (without going side to side from tapping the D-Pad turning input.

No matter what there is ALWAYS steering assist at play, making it incredibly easy to use either D-pad, Nubb, or DS3 Joystick.

Due to lack of analogue control over the Gas/Brake they give us a delayed input, that gives us a way to regulate the amount of input applied. Tapping the Gas/Brake and getting used to it so that your tapping speed dictates how much throttle or brake is applied. This makes it incredibly easier to apply the brakes without locking up. They have a static delay, not dependent on speed or other variables other then the programed delay and tap speed.

Cheers
 
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compared to gt3 the cars oversteer alot more. on gt3 the cars either spin, understeer or if you get it just right you will get around the corner without doing either and on one occasion i mannaged to hold a drift.

on a psp you feel a distinct differnce between cars. (ff,fr) and you can drift if you want to but if you go in to fast you understeer which on gtpsp means you are being a cock unlike gt3 when it means that you will start tearing your hair out.


( i don't have gt4 (doesn't work on my damn ps2))
 
I bet GT5 will have better AI physics than GT5P.. otherwise 16 cars on f.e Nürburgring would be a nightmare.. impossible to overtake.
 
I agree with everything from what I have so far seen.

Collisions
-Rarely ever airborne. In GT4 on high speed sections, such as Test Track, if you hit the wall at a sharp angle on purpose or by accident your car would pop up into the air to the point that with proper photomode camera angles I could make it look like my car was flying. At ~230 mph in both a Veyron and the Pescarolo Hybride C60 they just hit the wall and had significant speed reduction (The Pescarolo actually stopped head on into the wall, tires spinning once) with just a tiny bounce or they would begin an uncontrollable spin.

Hitting the AI head on, as described earlier, also resulted in very little flying through the air.

I've experienced otherwise. I've taken the Cusco out to Cathedral Rocks and I got MASSIVE air. Also, I was able to get HUGE air with the Pescarolo C60 on the test track. Mind you, I agree it is a lot harder to do this than in GT4. I have both replay's saved on my PSP 1000. It's actually pretty fun to watch the car spin out or jump the height of a car.
 
Dirty tires and enhanced AI are things I noticed as well. Can't comment on the comparison between GT4 and GT PSP under/oversteer, since I have never played GT4. The physics appear to be on par with GT5P, but I find it hard to judge since I play the latter with a G25.

As for going airborne after a collision: try a light-weight, high powered car like the Furai (650kg) and go over a curb on the Nurb, it will put its nose in the air as if it will take off. :) See this movie for an example (0:36 into movie/0:18 into race).
 
I've experienced otherwise. I've taken the Cusco out to Cathedral Rocks and I got MASSIVE air.
I am not talking about getting a jump. Jumps should and do happen. I am talking about being able to hit the wall in Test Track in GT4 and getting higher than any of the railing or fences. I can't replicate that.

Also, I was able to get HUGE air with the Pescarolo C60 on the test track. Mind you, I agree it is a lot harder to do this than in GT4. I have both replay's saved on my PSP 1000. It's actually pretty fun to watch the car spin out or jump the height of a car.
This is likely more along the lines of what I am talking about, but from my few tests I haven't seen this. Unless your car is bouncing back from the high side of the wall and coming off the track (judging by your spinning comment) in which case that isn't what I am referring to.

NLxAROSA
As for going airborne after a collision: try a light-weight, high powered car like the Furai (650kg) and go over a curb on the Nurb, it will put its nose in the air as if it will take off. See this movie for an example (0:36 into movie/0:18 into race).
Um, that's a bounce.


Here, I had to dig back to April, 2005 to find these pics, but this is what I am talking about.

http://img244.imageshack.us/img244/1460/img00766sk.jpg
http://img198.imageshack.us/img198/3527/liftoff1ip.jpg
https://www.gtplanet.net/forum/attachment.php?attachmentid=52888&d=1114684648

I haven't managed to replicate this. I have only attempted a few times though, so it may be possible, but it doesn't work the same way it did in GT4.
 
LOL.. that Minolta looks like its flying... Up, up and AWAAAYYYYY!!!
 
Does one get less downforce when he's in a slipstream?

In the real world

Yes, you go faster but lose grip (DF is reduced as your in the Slipstream) It takes less power to go as fast as the lead car pushing through the air, but you get less of the air that creates DF.

In GT

No, You go faster and appear to have more grip
 
In GT

No, You go faster and appear to have more grip

In GT2, when you're in the slipstream you lose downforce and grip. I can't say for sure if you lose grip while in the slipstream in GTPSP though, since I haven't been slipstreaming for long enough at any one time (Is it just me, or is it really hard to tail an AI in GTPSP? You either get left behind or pass them straight away). I wouldn't say it gives you more grip though, if that's the case then PD seriously messed up :ill:.
 
In GT5P/PSP, in the slipstream you lose downforce and therefore grip. you cant follow a car through a fast corner at the same speed as you normally could alone
 
Cool 👍. I figured they would bring back this effect (they removed it from GT3/4 haven't they?).
 
on a psp you feel a distinct difference between cars.

This is one of the best things to happen so far. In my games, I have started out with the lower end cars and worked my way up. I was pleasantly surprised to be able to easily tell from the first few corners of any track that even the low-powered Honda Beat felt and handled quite a bit differently from a similarly-powered Suzuki Cappuccino. In the earlier games of the GT series, this was not so apparent.

Each of the cars in the game are starting to show their own characteristics and this is a welcome change. 👍👍
 
In GT5P/PSP, in the slipstream you lose downforce and therefore grip. you cant follow a car through a fast corner at the same speed as you normally could alone

I dont really know if its true in GTPSP because I havent been able to draft long enough to see the effect... But in GT5:P I dont think this is not true... racing HSR 800PP online in GT5:P if youre slipstreaming you could take the first big left turn SUPER fast as long as you stay behind the person in front of you. If you would veer to side a bit out of the slipstream you would lose it and understeer badly into the wall while in the corner... but in my experience as long as you stay behind the car while youre in the corner you have massive amounts of grip and speed... I would say increase rather than decrease in DF and grip while slipstreaming... but I could be mistaken... Im only going by my experience here and what I felt through the wheel while racing... 👍
 
I went back to the Test Course and did some testing, and I couldn't feel the slightest amount of Grip Loss when in a slipstream. The car actually felt GLUED to the road, until the slipstream is broken.

Grab the corner tucked in behind the AI and you can literally ride his bumper through the corner, and sling shot past him on exit with as much effort as it takes to just carve it.

I didn't feel any Grip loss at all.

My only issue is not being able to adjust the gears so the car doesn't bounce off the rev limiter.
 
Well at 200mph+ you're not going to notice a lack of grip because even in a draft, the amount of downforce being produced is going to be pushing down on the car considerably.

The best way to test that theory is to drive a proper circuit and stay behind the AI. I think you will notice a considerable lack of grip.

I do. Try following a car in its slipstream into a corner, breaking at the same point you would while not following a car and tell me can easily follow the same line you would normally. If you notice no difference then try the same again but pull out of the slipstream before you brake.
 
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