Oversteer Racing: Dev blog #26 – The one where we toe in rather than toe out

It's been another busy month and once again I've been focussing my efforts on obstacle avoidance... it's been some time now since I've looked at anything else!

However, I'm starting to make progress and, although there are still a few collisions, the AI behaviour is getting to the point where some accidents are avoided and the cars are more challenging to race against. The key to the improvement was some time spent tweaking the values that control when an AI car will choose to avoid another car and how the AI cars detect other cars. On this last point I'd primarily been using three raycasts at the front of the car. These can be seen in this screenshot (from last month's devblog):-

Non-player cars failing to avoid each other

I was using a central raycast with another on either side angled out from the car. The result was inconsistent as, initially, AI cars would turn to avoid another car but but often wouldn't turn enough and, as a result, would clip the edge of another car.

By setting up scenarios where cars needed to take avoiding action and stepping through the action I could see the issue. Initially the cars would detect an obstacle and turn to avoid it. This change of direction meant the obstacle would not be directly in front of the car. At this point the left or right angled raycast would detect the obstacle. The car would then turn some more to avoid the obstacle. However, as the car got closer to the obstacle then the angle of the side raycasts meant that the obstacle wouldn't be detected when close to the car. This meant that the cars would move to avoid the obstacle but stop detecting it when it was close and therefore not move enough.

The solution was to "toe-in" the raycasts rather than have them "toe-out" as was the case originally. This means that the AI cars are more 'concerned' with objects that are directly in front of them at long range but less concerned about objects that are in front but off to one side. As the AI car approaches the obstacle then the side raycasts are increasingly likely to detect a side obstacle as well as one in front. The result is a more consistent move to avoid an obstacle.

Screenshot showing raycasts on an NPC car

The AI cars won't always avoid an obstacle but their behaviour is more consistent and they are generally "doing the right thing" now. One other benefit has been that AI car behaviour when racing wheel-to-wheel is also more challenging now - as can be seen by this clip of the red AI car racing against the player (blue and white car).

Animated gif showing AI racing behaviour

Oversteer Racing: Dev blog #25 – The one where it's hit and miss, although mainly hit

Recently I've been working on AI behaviour for the rival cars. The main focus has been convincing the non-player cars to avoid other cars rather than slamming into the back of them. As Oversteer Racing has a more realistic damage model than some top-down racers collisions tend to be more serious than in other games.

One downside of the non-player cars following a series of potential routes around the track means that they have no knowledge of where the edge of the track is. This makes things difficult when it comes to avoiding objects because it's hard to work out which way to turn to avoid the object. For example, if a car has stopped on track then can the non-player cars pass to the left or to the right without leaving the track?

The work I've been doing uses a number of ray-casts from the cars to detect obstacles. Once an obstacle has been detected I use the route markers to determine which side of the track has more space. The car then steers towards that space.

This is still a work in progress as the cars are not consistently avoiding obstacles. To some degree I'm happy if the cars don't always get this right because that seems more realistic but, at present, the non-player cars get this more wrong than right...

Non-player cars failing to avoid each other

Non-player cars failing to avoid each other

Oversteer Racing: Dev blog #24 - The one where we think about the money

Wow, dev blog 24.... that must mean I've been blogging about Oversteer Racing for two years... ouch. I'd have hoped to have more to show by this point but the game is something that I can only work on in my spare time and that's an unpredictable quantity. Also, the game is a labour of love, something I want to do but also something I don't want to feel like a chore.

Although the game is a labour of love I do want to include some sort of monetisation. It's not like I'm expecting to retire on the profits but having a bit of income to help pay for my business costs or assets for my next game or even updates to Oversteer Racing would be nice.

I've previously mentioned some of my thoughts on monetisation and I've given this more thought recently. Having read a few game reviews on the app store it seems that more and more players understand that free-to-play games aren't free to create and that it's important for developers to earn some money from their efforts (if only to fund future work rather than make a profit). However, there's a very clear dislike for large numbers of adverts and many players feeling like the number of ads they see are disproportionate to the amount of playing time they spend in the game. I've seen reviews talking about seeing a minute of video ads following a game session that lasted 30s.

In Oversteer Racing it's clear that the playing time will be quite long. I'm aiming for laps to take around 25s so, even a short 10 lap race would take at least 4 minutes. Consequently showing an advert after a race would not seem, on the face of it, to be disproportionate. I may need to make some concessions though. For example, if you crash out early then perhaps I wouldn't show an ad and maybe I wouldn't show an ad after all races. I definitely don't want to show adverts between menu screens as that, for me, seems pretty aggressive.

I also want people to be able to pay to remove the ads completely. As a parent, and from talking to other parents, I know that this is something that people often want to do for games that their children enjoy.


If people do want to see ads and, as a developer, I'm receiving money for that then I'd also like people to be rewarded. They may not have paid for the game but at some level the amount of income generated by an individual player watching ads would reach the level that someone might reasonably have paid for a game (even though it's free-to-play). At that point I think people should be "rewarded" even though this contradicts the view of some companies where players are "monetised" throughout the entire time they play the game.

I'm not sure what decisions I'll take in the end but it seems to me that if a player has invested a lot of time in the game then they could be rewarded for that. In a lot of games these people would be seen differently and as a source of continued revenue. My current thinking is that people who watch enough ads to have generated a certain amount of revenue should have access to similar content as anyone who pays. So, for example, if I have an option to purchase new tracks then anyone who "pays" a similar amount through ads should get that content too.

Next month...

I'll be returning to AI for the rival cars and specifically looking at how cars behave when near other cars and obstacle avoidance.

Oversteer Racing: Dev blog #23 – The one where we reverse a bit

So this month has been a bit interesting as I have found some time to work on Oversteer Racing, not as much as I'd have liked, but a bit.

Although I've found some time to work on Oversteer Racing I don't have a lot to show for it. I've spent a fair bit of time refactoring some code to make it more useful. Specifically I've taken the code that I use to determine how long a player remains stationary in the pit box and made it more generic so that it can be used to work out the length of a stop for all cars. So, whilst I've done a fair bit of work I've actually got very little to show for it from the outside 😉

I do have some tasks left on pit stops before I move onto something else (it feels like I've been working on this code for the entire year so far) but I'm definitely making progress. The remaining tasks are to hook up the code for calculating a pit stop with the AI code for the rival cars. I then need to make sure the rival cars are correctly fuelled, damage is fixed and so on. At that point I think I can move on to something else... 🙂

Next month

Next month I plan to finish off the remaining pit stop tasks and then start looking at obstacle avoidance for rival cars.

Oversteer Racing: Dev blog #22 - The one where the wheels come off

I have to be honest, it's been a really bad month for spending any time on Oversteer Racing. I had a huge piece of work (for another project) to finish at the end of May and that left me exhausted and the last thing I wanted to do was spend even more time coding. I've been surprised how much working at a consistently high pace for an extended period of time has taken out of me. As a result I've been spending some time doing other things and taking a bit of a break.

That said, I'm never a fan of stopping work on something completely as the overcoming inertia and restarting can be pretty difficult... so I have done some work on Oversteer Racing. The work I've been doing has still be focused on pit stops. Building on the work from last month (where the rival cars were passing through the pits without stopping), the rival cars now turn into their pit box and then move out into the pit lane again in order to leave the pits.

I'm also happy with the code that allows the rival cars decide whether they should be pitting or not. So there's a good amount of groundwork done for the "race craft" of the rival cars.

Next month

I need to determine how long rival cars should stop for.

Oversteer Racing: Dev blog #21 - The one where we pass through

As suggested last month, it's been another fairly quiet month in terms of work on Oversteer Racing. Part of the problem of being a 5-9 developer, or more often a 10pm to 12am developer, is that it's very easy for other commitments to get in the way of the small window of time you have to work on a project. Also, even when you do have a bit of free time, your day job can leave you exhausted and not in the mood to do more coding late into the night.

That said, I did manage to do some work on pit stops for rival cars. I've got a working version of the code allowing the cars to decide when to stop based on fuel usage, tyre life, their team mates, damage and the progress of the race. I've also set up the paths for the AI cars to follow so that they can enter the pit lane, turn into the pit box and then exit the pits.

At the moment the rival cars don't stop in their pit box and refuel, change tyre or replace damaged parts. This is the next piece of work that I need to do and I'm hoping that I'll have a bit more time to work on this in June.

Oversteer Racing: Dev blog #20 - The one where nothing happens

It's been a pretty poor month to be honest. I've had so many other things taking my attention away from Oversteer Racing that it's been very difficult to complete any tasks.

All I've managed to do this month is:

  • Fixed a bug that meant the dust particles kept playing after the car had stopped moving
  • Fixed a bug that meant the lap counter may occasionally miscount the number of laps completed
  • Fixed several bugs in the code for calculating the time gaps between cars and for also calculating lap split times

Unfortunately, for a variety of reasons, I don't think next month is going to be much better than this month in terms of my time. However, there is some light at the end of the tunnel for June.

Oversteer Racing: Dev blog #19 – The one where I had to do something else

It's been a really busy month and I've had to spend quite a lot of time on one of my other projects, my fantasy F1 competition. It's always the same this time of year because of the start of the F1 season and the hard deadline that the start of the season represents. The game needs to launch a couple of weeks before the first race in order to give people the time to sign up. The hard part is picking the right cost for the drivers and teams so that there is a high number of possible teams but it's not easy for players to pick teams with lots of good components. Once the game has launched I can't change the value of the components so, if I get it wrong, then it can have a detrimental effect on the game for the entire season.

But, back to Oversteer Racing, what have I achieved in the last month?

Unfortunately the answer is not a lot.... but I did do something, no really. I found and fixed a bug that caused the sand/dust particle system to continue playing after a car had left the track but was now stationary. Unfortunately that's all I've managed to do and that's pretty disappointing but, when you're one person working on a game then, when you have to stop to do something else, all progress stops.

Next month

I really hope to be back working on the AI code again. I need to get this finished off so I can move on to other things.

Oversteer Racing: Dev blog #18 – The one where we can't count

It's been an interesting month. I've not made much progress on new features but once I started adding AI cars into the game it uncovered a few issues.... so I've been focusing on fixing those.

1, 2, 3 ... er

As I'm now able to add AI cars to the game I thought I'd add some code to show the current race order. Unfortunately that's where things went awry...

The main issue was that the lap counter would sometimes lose count, particularly for the player car. Obviously being able to count the number of laps a car has done is fundamental to circuit racing. The AI cars accurately keep track of the number of laps completed but the player car would value would drift and end up one to two laps off. Fortunately the issue turned out to be fairly simple and one that was only triggered when more than one car was on track. This was why I hadn't spotted the issue when I'd written the lap counter code and it only came to light at this stage. Easily fixed though.

The second issue was that there was a bug in the code that works out the split times between the player car and the car ahead and the one behind (as appropriate). This worked reasonably well but there was an intermittent issue whereby the time for the split to the car behind would occasionally be calculated as over 20 seconds when the gap was actually much, much lower. This turned out to only happen when cars were on different laps. So, when the lead car crosses the start/finish line it's a lap further on than the following car. At this point the code should look to the previous sector entry times to determine the split. Instead it was using the current sector of the lead car and looking back a lap to when the following car entered the same sector - which explains the discrepancy. By the time the split was next calculated the cars had often moved to another track section and the code got the comparison correct and showed the correct split time.

Next month

I'll be back working on the AI code for rival cars.

Oversteer Racing: Dev blog #17 – The one where we make plans

It's been a very busy January and there's always a bunch of "admin" stuff to do. So a lot of my time has been spent doing my personal tax return, company accounts and company tax return etc. Talking about that in my latest dev blog is not going to be a rivetting read so I've decided to focus on my plans for the coming year.

Get the game into players' hands

OK, so this may be optimistic given that I'm working on this in my spare time but I think it's possible. Afterall, I've been deliberately vague about what the above means. Ideally I'd have the game out and available but I think it will also be a reasonable achievement to have reached the point where the game can be tested by a few people. If you're interested in doing this then do let me know although, in all honesty, I'm unlikely to have a ‘testable' version of the game before the Autumn.

More of the time, all of the time

There's no escaping the fact that the major issue affecting how the game is developing is a lack of time on my part. I can't see this changing significantly but what I can try and do is set aside more time more regularly. The beginning of the year has been filled with a number of admin tasks as I mentioned but I've also had some coding work to do on other projects... and sometimes I just need a break from coding 😉 However, I think the only way I can improve the situation is to set aside the same bit of time each week to work on the game. this has the benefit of having a clear time that I can work towards each week. Odd things are bound to crop up from time to time and mean that this isn't always possible but I think it's likely to pay off overall.

Recent work...

This past month I've made some improvements to how the car behaves when it's receiving a tow and when it's entering/leaving the gravel traps etc. This makes the car behaviour seem more natural but also provides important benefits to overtaking. The changes mean that, when pulling out from behind a car to pass, the advantage of the tow now decreases gradually and allows the overtaking car to carry the extra speed for a bit longer and this helps it make the pass.

Next month

I'll be working on the AI code for the rival cars. At present they'll lap the circuit reasonably well and can take alternative lines. However, what they don't do is challenge for position and that's my next task.