CC Line & Track Editing - Often Overlooked

I've been revisiting some tracks and refining the CC Line recently, and I just wanted to say what a difference it makes to the racing. I've read a few things here and there about how best to edit it, etc. but it's worth pointing out what a difference it makes as don't see that many topics about it.

I was editing Suzuka, and I wasn't happy with the line the AI takes through the hairpin after the Degna turns. They leave the door way open and take way too long to get back on the throttle once they've hit the apex. I've been messing around with the line, and am shocked by how much difference it's made to be honest, and how much better it's made the racing. The basic result is that now they don't leave the door wide open at all, and if I overshoot the apex then they will often undercut me and out-accelerate me out of the corner. Normally on GP4, if you beat anyone into a corner, I find you're pretty much guaranteed to beat them out of it.

So just to say to people doing track editing, etc. that the CC line can make a huge difference to the racing, and you can really use the curve radii etc to affect how the AI cars drive - it's more than just them getting round the track, you can affect how aggressive they are and how they take a good defensive line, can really make a good track great.

Anyone else got any thoughts or tips on CC Lines? Or if you are track editing and want some help or whatever with how to get the CC Line working well, leme know

Nice! Could you contact cleberpister? He is doing various trackpacks, maybe you can send Suzuka CC-line to him and work on other tracks.

Thanks for share the knowledge.

------------------------------------------------------------------------------------------------

PLEASE VISIT: Grand Prix Mods Blog

Yes,

Good post you have right
You can win maby 1.5 sec in that corner.

Absolutely right, actually that's the first thing I noticed - the lap time was instantly over a second faster!

Nice post mate. Little bits of info like this is what makes the community better as a whole.

---

Retro Liveries on the SMD-ZG02![www.grandprixgames.org]
Retro Renders 2.0 on the SMD-ZG02LN![www.grandprixgames.org]

TeamBPR, can you post a before/after screenshot of your cc-line in the hairpin? I'm curious.


My unfinished tracks: [www.grandprixgames.org]
Send bug reports and track editing questions to f1virtualblog@gmail.com

i often have many trouble making a good cc-line, so a help could be very useful

-------------- My GP4 Tracks --------------
F1 Tracks , Oval Tracks, Other Tracks

I would happily make a video, but I have tried FRAPS and it's just useless, the FPS is horrendous so much so that I can't make it properly. Anyone know better techniques for making a video? I don't have the old CC Line, so I can't really make a before. I can show you what it's like now though maybe, if I can make a decent video!

There are some very definite ways in which we can improve CC line, it's all about affecting how they slow down/speed up out of corners, you can draw what looks like an identical line, ut depending on how you use the curve radius and section lengths etc you can totally change how they drive it.

TeamBPR Wrote:
-------------------------------------------------------
> ...
> Anyone else got any thoughts or tips on CC Lines?
> ...

I 've edited quite some CC lines and I can add these tips from my experience:

- Avoid changing the curve radius in the middle sectors of a turn with small curve radius.
If possible, use a cc-line sector with constant radius throught the turn. That's the ideal situation.
In case this is not possible, or does not fit the track layout, use cc-line sectors with curve2 option enabled. Set the curve1 value of the next cc-line sector equal to the curve2 value of the previous cc-line sector, to achieve a smooth transition.

- Avoid cc-line section with length 1 sector, between cc-line section with small curve radius. Will make cc-cars go instantly to full "throttle" and immediately to full "brake" which in not normal way of driving.

- Always use "Shift" option in cc-line section with small curve radius that follow a more straight cc-line section, e.g. at a hair-pin entrance. Shifting the curve outwards will align it's first sector with the last sector of the previous straight cc-line section, allowing a smooth transition for the cc-cars while finish breaking and start turning. (If needed, reduce one sector from the previous cc-line sector - you'll notice that while editing).

I uploaded cc-lines for Interlagos2008 and Montreal2010, for anyone interested to test my work.
You may get them from my signature.

_________________________
some of my GP4 works ...

Hiya Cyberacer

Interesting. The 1 length sectors is a good point, I always delete those from tracks I am editing.

One thing I wasn't aware of was the shift. I didn't know what it does so I have never edited. What does it do exactly??

With regard to curve radii one thing I have always done which is different to what you described, but I'm not saying it's better.. is to split a corner into two sectors. Both sectors have two curves. Here's an example:

Sector 1
Curve 1: 12500
Curve 2: 10500

Sector 2:
Curve 1: 10500
Curve 2: 13000

The idea here being that the car slows down to it's slowest speed before the apex, you split the sectors so the slowest/tightest curve is just before the apex. Then the car should accelerate out of the corner, as humans drive it. This makes it harder to pass the AI out of corners. It's also how you drive in real life - slow in, fast out, that's the golden rule.

Constant radius is ok with some corners, but it seems to cause the AI to sit half on the throttle the whole way through it and then gently accelerate away from the corner's apex, where in fact you should slow down FOR and a corner and DRIVE OUT of it... again slow in, fast out.

Can you share more about the "Shift"...?

TeamBPR Wrote:
-------------------------------------------------------
> ....
> With regard to curve radii one thing I have always
> done which is different to what you described,
> but I'm not saying it's better.. is to split a
> corner into two sectors. Both sectors have two
> curves. Here's an example:
>
> Sector 1
> Curve 1: 12500
> Curve 2: 10500
>
> Sector 2:
> Curve 1: 10500
> Curve 2: 13000
>
> The idea here being that the car slows down to
> it's slowest speed before the apex, you split the
> sectors so the slowest/tightest curve is just
> before the apex. Then the car should accelerate
> out of the corner, as humans drive it. This makes
> it harder to pass the AI out of corners. It's
> also how you drive in real life - slow in, fast
> out, that's the golden rule.



What you do is just correct. It's what I described as:
"... use cc-line sectors with curve2 option enabled. Set the curve1 value of the next cc-line sector equal to the curve2 value of the previous cc-line sector, to achieve a smooth transition."


Constant radius permits in some cases higher speeds through the apex.
In your example...

> Sector 1
> Curve 1: 12500
> Curve 2: 10500
>
> Sector 2:
> Curve 1: 10500
> Curve 2: 13000
>

... if I can use a constant radius of e.g. 11500, it would allow higher speed through the apex.
In that case, as TeamBPR correctly says:

> Constant radius is ok with some corners, but it
> seems to cause the AI to sit half on the throttle
> the whole way through it and then gently
> accelerate away from the corner's apex,

and this is something we see often in on-board videos of real F1 at tight turns or hair-pins.
We see drivers sit half on the throttle and then go full throttle.

But when it comes to GP4, what I really think is that whatever way of the two (constant or variable curve radius) you choose to design a tight cc-line section, it will have no significant effect in the lap time.



TeamBPR Wrote:
-------------------------------------------------------
> One thing I wasn't aware of was the shift. I
> didn't know what it does so I have never edited.
> What does it do exactly??
>...
> Can you share more about the "Shift"...?


"Shift" allows moving the end of the first sector of a cc-line section outwards or inwards.
I 'll give an example from the Montreal2010cc-line I've edited:

Here's the un-shifted curve.
We see that first "red"sector of the turning cc-line section causes an immediate change of direction of the AI cars.
This is not good, as the cars still brake and affects badly their stability and driving performance while entering the curve.





Now let's see the same section after using "shift":

The first red sector is now aligned in the same straight line as the previous cc-line section, nr. 29.
cc-line section 29 is now 1 sector shorter: length is now 12 - was 13 in the unshifted version.
cc-line section 30 is now 1 sector longer: length is now 15 - was 14 in the unshifted version.
Practically we "moved" the last "straight" sector of cc-line section 29 to the turning cc-line section 30.
AI cars now enter the "turning situation" of section 30, without the need for immediate change of direction and the transition to turning is much smoother and natural.




I think now is more clear the way "shifting" works when entering tight turns.

I also use it in some cases to cause or correct minor deviations in curves of wide radius or even straight sections, to make the cc-line pass exactly where I want to and to make it fit better to the specific track layout.
In some cases I have noticed that I can bring the end of a cc-line section to the desired spot on the track, by changing a little bit its radius or by shifting it a little bit.
Choosing "radius change" or "shifting" affects differently the shape of the following sections of the cc-line, so I choose what gives better results.

... after all, making a good cc-line is a piece of artwork ...

_________________________
some of my GP4 works ...

I came across this old post and am intrigued by it as it may very well be key to curing some of my frustrations. On many of the aftermarket GP4 tracks, my car (meaning me and my young boys' car is constantly getting outbraked into corners by the AI cars. It doesn't do it on most tracks, though, only some which tells me there is something in the track settings that may be tweaked to fix this. I have all of the GP4 tools but I am mostly a player - not a programmer - and thus would probably quickly get over my head if I started jacking with some of those files too much. Any advice would be helpful. Thanks, AustinF1

@AustinF1: I would think a simple step or two down on difficulty would solve the vast majority of the issue. In case you already drive on rookie, well, then I can only suggest practicing more because deliberately building slower, sub-optimal CC-lines for a lot of tracks is a very grinding work and one that quickly becomes unproductive.

*

As for the bumped topic, it was certainly a very interesting read.

I think constant radius curves rarely fit an ideal line and can still be messed up besides - most often, if the end of a constant radius curve (any kind of curve, in fact) points off the track, and it's rather easy to do so with trying to get the cars back inside with another curve, it causes the AI to decelerate sharply at the end of it. No matter the next curve actually keeps the line on the track, if they continued to accelerate, they would run off the track.

So when you look at real world lines, it's most often a mix of decreasing and increasing radius curves which - if nailed - indeed gives the best laptime in GP4 as well. Problem is, once these Curve 2 values come into play, it can be rather hard to nail them, and that's when the dreaded mid-corner AI deceleration comes up. E. g. when following up a decreasing radius curve, it seems to be a rule to use a higher value for the next one than the Curve 2 value of the decreasing one, but by how much higher depends on corner speed (the lower the speed is, the higher difference you need). So, in the end, it becomes a huge trial-and-error process which can be a bit painful.

Understanding why real world cars position themselves as such that the line they draw fits decreasing/increasing radius lines is very easy. Decreasing radius is most prevalent on corner entry and is a result of trail-braking, which real world F1 cars often do due to their immense downforce they can rely on to keep the rear in check. Increasing radius on exit is there for a similar reason. The longer the actual turn is, the more noticeable such lines are (Barcelona is a nightmare) - which means you can get away with using constant radii in lower speed corners.

Also, a note on the "slow in, fast out" principle - basically, the only place where it's almost uniquely applicable is NASCAR/IndyCar, because of the long straights of their ovals. It's entirely dependent on where you can make up more time - slow in, fast out if there's a sizeable full throttle period after the turn and/or your entry speed into the actual turn is low, and fast in, slow out (i. e. really drastic trail-braking in a decreasing radius line) if the following straight is short and/or your entry speed is mega. A classic example of the latter is Sepang's Turn 1.

The amount up to which you compromise the exit of a turn follows similar principles - the the more important the next corner/straight is, the more you sacrifice your current corner's exit.

Finally, thanks for the info on the actual mechanism of the Shift value, I didn't know that one. I always used it when a curve juuust didn't fit in and I wasn't too keen on beginning the corner one sector later and using a lower radius - so I just kind of shifted it outwards a bit. But since GP4 Builder 1.912 XE stopped supporting the feature, I stopped using it and I'm fine with it - you can still use decreasing/increasing radius lines to compensate.

---

My workthread - [www.grandprixgames.org]
Full of classic F1/non-F1 track layouts

My blog about F1 performance analysis - [thef1formbook.wordpress.com]



Edited 3 time(s). Last edit at 06/11/2015 12:04PM by Atticus..

I'd be interested to have those pictures back in Cyberacer's post - I've never really understood shifting in cc-lines.

=====================================================


Intel NUC 8i3, 8GB RAM, MS Sidewinder Wheel