Inherent Unity 'randomness' gone?

[Tachrayonic]

I was building a track, set up a checkpoint in mid air, and tested it out. No big deal, the car fell and crashed. I let it respawn itself. It fell and crashed again, in exactly the same way.

On the way down, the car buped against it's roof, front, wheels, roof again, wheels and finally exploded by hitting it's side. Everything it hit was static, there were no rotating or otherwise moving objects on the way down.

If anyone wants to make a 'Don't Do Anything' (DDA) level, it may be possible.

Edit: Just checked it with lasers, they do not create a random event, and the car will continue to fall exactly the same way every time before and after it is sliced.

[Californ1a]

The physics reactions are based on your fps, so if you are running on integrated gfx, then the same thing will not happen with the same inputs as if you had played on a beast machine.

[Tachrayonic]

Aah, fair enough. The track I was on had very few objects in it too, so there was no reason for the fps to drop.

[Cluh]

To clarify, physics are not dependant on framerate, they always run at 100fps, and if the framerate drops too low, the game (at least physics) will slow down time to compensate. However, last I checked, the physics are not deterministic. I had dreams of this early on, did extensive testing, and concluded that I cannot depend on that. I read elsewhere that PhysX, the physics engine Unity uses, is not and does not plan to be determinisitic. To create a game like Trackmania that is perfectly repeatable takes a lot of work, will inherantly be more taxing on the CPU(but only slightly if done correctly), and probably an engine built from the ground up with that in mind.

That said, I wouldn't mind taking a second look at this, though a LOT would need to be rewritten to be able to support this with our game, and I don't have plans to make those changes.

[Californ1a]

If you're going to have a look at it anyway, maybe you could look into the maps that use the popup blockers to "bounce" the car somewhere, since those seem to be the most random/inconsistent thing (physics-wise). Mostly, it'd just be nice to be able to have the car at a consistent or at least "manageable" angle (air-control-wise) after being bounced instead of flipping and spinning all over.
http://steamcommunity.com/sharedfiles/filedetails/?id=575930650
http://steamcommunity.com/sharedfiles/filedetails/?id=409078289
(probably more, only two I could think of) The one in Colors isn't that bad, but the ones in Propulsion have a tendency to send you in some odd trajectories sometimes (i think it's likely because of the spinning fit the car goes into when it gets bounced combined with boosting, sending you somewhere off-trajectory)

There's also this map where you have to transfer as if onto a wallride, but onto a saw, and fling off it. This also produces a ton of inconsistent spinning.

[Tachrayonic]

Speaking of 'bounce pads', it can be very difficult to set them up reliably as they have a shperical detection area. I had to do a lot of tweaking to get the pads not to explode the car when you hit it head on, and coming at a pad from a different approach can have vastly different results. Putting the pads on a wall or ceiling also needed an extra amount of tweaking, almost as if the detection area didn't rotate with the rest of the pad.

As for having a deterministic physics engine, while you won't lose anything by achieving it, I doubt most of the playerbase would even notice the difference. The biggest reason I can see for it would be to iron out edge cases where one player could have a lucky day to get an effectively unbeatable record time.
There are a couple of specifc things you can only accomplish in a deterministic environment, but I don't think this game really needs it.

[Californ1a]

Originally posted by Platoonsgt1:

The biggest reason I can see for it would be to iron out edge cases where one player could have a lucky day to get an effectively unbeatable record time.

Makes me think of damage boosting off of rollers or saws in challenge maps.

[Cluh]

Originally posted by Californ1a:

If you're going to have a look at it anyway, maybe you could look into the maps that use the popup blockers to "bounce" the car somewhere, since those seem to be the most random/inconsistent thing (physics-wise). Mostly, it'd just be nice to be able to have the car at a consistent or at least "manageable" angle (air-control-wise) after being bounced instead of flipping and spinning all over.

This technique lost its reliability when we switched over to Unity 5, and car physics got flipped on its head. When first making the switch, these pop-up jumps would simply not affect the car, and just go through it. I attempted to fix it but changing the collision type, but you are correct that it is inconsistant. Though thank you for mentioning it, because I do have an idea that could help. I'll try implementing that soon, and see if that helps.

Originally posted by Californ1a:

There's also this map where you have to transfer as if onto a wallride, but onto a saw, and fling off it. This also produces a ton of inconsistent spinning.

Haha, I'll look at the too, but we can't exactly count on saw riding being consistant.

Originally posted by Platoonsgt1:

Speaking of 'bounce pads', it can be very difficult to set them up reliably as they have a shperical detection area. I had to do a lot of tweaking to get the pads not to explode the car when you hit it head on, and coming at a pad from a different approach can have vastly different results. Putting the pads on a wall or ceiling also needed an extra amount of tweaking, almost as if the detection area didn't rotate with the rest of the pad.

completely agree here, adjusting close range popup blockers is a royal pain. We've been meaning to fix this one for ages, and so it's high time to tackle it.

Originally posted by Platoonsgt1:

As for having a deterministic physics engine, while you won't lose anything by achieving it, I doubt most of the playerbase would even notice the difference. The biggest reason I can see for it would be to iron out edge cases where one player could have a lucky day to get an effectively unbeatable record time.
There are a couple of specifc things you can only accomplish in a deterministic environment, but I don't think this game really needs it.

Yeah, I just don't see the benefits outweighing the costs.

[Californ1a]

Originally posted by Cluh:

Originally posted by Californ1a:

There's also this map where you have to transfer as if onto a wallride, but onto a saw, and fling off it. This also produces a ton of inconsistent spinning.

Haha, I'll look at the too, but we can't exactly count on saw riding being consistant.

That reminds me... driving on basically any moving/rotating object causes you to visually (but not really physically) skid/drift. This especially affects EmpireBuilding001, since it's such a tall building, it's a very common one for us to land on and use in trackmogrify routes to quickly get up high. It's just a bit odd driving straight, but the car model visually appears as though it's driving diagonally. It's much better than it used to be with U4 where you would actually physically drift, but it just visually looks a little odd, even if the physics are behaving properly.

[Cluh]

Originally posted by Californ1a:

That reminds me... driving on basically any moving/rotating object causes you to visually (but not really physically) skid/drift. This especially affects EmpireBuilding001, since it's such a tall building, it's a very common one for us to land on and use in trackmogrify routes to quickly get up high. It's just a bit odd driving straight, but the car model visually appears as though it's driving diagonally. It's much better than it used to be with U4 where you would actually physically drift, but it just visually looks a little odd, even if the physics are behaving properly.

Just tested, seems to actually be the camera itself which is following from an angle because the car is technically moving to the side since the building it is on is moving it in that direction.

[Californ1a]

Originally posted by Cluh:

Just tested, seems to actually be the camera itself which is following from an angle because the car is technically moving to the side since the building it is on is moving it in that direction.

Interesting, never considered that it could be the camera itself which was off.

[Californ1a]

I guess we're talking physics here, so I'll cross-post this, no idea if it has to do with object hitboxes or physics, but my second paragraph in this post and the videos in the subsequent post explains it.

[Cluh]

Originally posted by Californ1a:

I guess we're talking physics here, so I'll cross-post this, no idea if it has to do with object hitboxes or physics, but my second paragraph in this post and the videos in the subsequent post explains it.

Yeah, I'm aware of this unfortunate bug, which is within Unity, and arises whenever objects are scaled really large. I submitted a bug report to Unity about this issue a few months back, and got confirmation that my submission was helpful, so I am hopeful. I'll let you know if anything arises from this.

[Californ1a]

Ah, well, that is unfortunate.

The only other physics stuff I can think of would be this where you can slide on the roof across the killgrid. In NR, it was the opposite, you could drive on the killgrid as long as the body of the car never touched it, but in Distance it seems to be that you can side on it with the body as long as the wheels don't touch. No idea if that's even worth fixing though. (and thrusterboosting :P)

[Cluh]

Originally posted by Californ1a:

Ah, well, that is unfortunate.

The only other physics stuff I can think of would be this where you can slide on the roof across the killgrid. In NR, it was the opposite, you could drive on the killgrid as long as the body of the car never touched it, but in Distance it seems to be that you can side on it with the body as long as the wheels don't touch. No idea if that's even worth fixing though. (and thrusterboosting :P)

Actually nitronic's killgrid was exactly the same as distance. The places youe could drive on were kill boxes, not the main grid. Personally I absolutely love the boat levels. And thrusterboosting... yes, currently tackling that, along with other car balancing issues, part of that includes reading through and responding to that thread, expect that next week.

And, when looking again at the bounce pads, unfortunately, my possible solution isn't possible, ass those are moving so fast that the pads is entirely through the car in less than a frame, so it's really up to whatever Unity's physics decide to do with the car.

[Californ1a]

Originally posted by Cluh:

Actually nitronic's killgrid was exactly the same as distance. The places youe could drive on were kill boxes, not the main grid. Personally I absolutely love the boat levels.

Oh yea, I didn't want to break their maps, it's pretty interesting and doesn't really cause any issues.

Originally posted by Cluh:

And thrusterboosting... yes, currently tackling that, along with other car balancing issues, part of that includes reading through and responding to that thread, expect that next week.

Ah sweet, thanks for all the replies and community interaction with this stuff. Would "other car balancing issues" include balancing the other vehicle (separate or filterable leaderboards, per-map per-vehicle)? It'd be great to not have all vehicles on the same board (or least be able to filter to only show a specific vehicle, if it shows them all by default), so you could actually pick which vehicle replays/ghosts you want, after replay mode is out. And people near the top of the boards wouldn't be directly comparing times across multiple vehicles. I always think competition when I hear balancing issues ¯\_(ツ)_/¯

Also, did you see the camera bug in this video whenever I drive off one of the shards? It seems to zoom in on the back of the car for a single frame.

Originally posted by Cluh:

those are moving so fast that the pads is entirely through the car in less than a frame

That's pretty hilarious actually xD