Gaming Your Way

May contain nuts.

Lessons learned the hard way, part 100

Right now I have next to no time for working on MTR, as it's December - which means that about a million client projects should be finished by the end of the month.

Getting my ass up and continue coding after doing it for 12 hours is, let's be candid here, not easy and most of the time I just want to drop myself onto the couch and play for an hour. Right now I'm playing Assasin's Creed 4 (Black Flag) on the XBox One, which is reasonable fun, if you overlook the fact that the novelty has worn off a bit after 30 games with the "same" theme. But the open world and the the lush caribbean environments make up a lot. I event spent some time just sailing between the small island and hunt down the "hidden" items scattered around the map.

Back to the title of the post, which isn't as unrelated to the post as usually.

In the post about the new HUD I mentioned that I want the thing to be dynamic and showing the order of the cars while they progress through the race. With this idea I coded a little sort function that creates orders the cars according to their position on the track. The idea is simple enough: every time a car hits a waypoint, I store it away and use it to sort, higher waypoint id means better position. As the ids start with 0 after a round I just add 1000 for each lap and that problem is solved, too.

There might be the chance that two cars share the same waypoint and this is taken care of by comparing the time when the cars hit the waypoint making the one with the lowest time first.

The first version of this updated the position of the HUD each time a waypoint was his and espeacially in the early stages of the race this could change quite frequently, causing an ever moving HUD (which was quite distracting, tbh). The second thing that didn't work out like planned (quite logical now, but I didn't see this when I thought of it) is the way the time is displayed. I only wanted to show the current time on the first car and show only the difference to the first on the other cars. Yet again, during the start of the race there is nearly no difference, resulting in changing 1/100 secs, which didn't help at all. I'm going to test if I may stop the time for 2nd, 3rd and 4th car, showing a fixed difference (instead of a running time) to the first car and update it only every odd waypoint. Either that or I drop that and just show the race time ...

No image this time (it would just show the track, 4 cars and the HUD anyway), maybe next week ...

-- Oliver/nGFX

New rules ...

It seems that I'm now a proud member of the Iron Blogger Community, in my personal case it's The idea is to write at least one post per week or you have to pay a fee (which is used to buy beer when we meet once a while).

Announcing that I'm now a member of an Iron Blogger "chapter" counts as a post for that week, but that would be a bit lame.

I'd like to post some progress on the MTR racing game and as a surprise ... I even have to report some progress - sort of.

I'm not sure if I mentioned how the AI in MTR works, but I guess I might repeat myself to get to the point.
When I posted the last time the AI was using waypoints to move along the track and not, say, a fixed spline (which would be oh-so-much easier). I use waypoints, because there is a track editor build in and players can build their own tracks, if fact I do some blending between waypoints so it's nearly a spline.

Anyway, the trick is to actually hit the waypoints when moving along the track, because sometimes you're coming a bit to fast down a ramp and the "hit waypoint" radius is just the few digits to small and so you missed your target waypoint. Detecting that is quite easy - if the allowed angle between driving direction and car/waypoint is too big, we simple jump on to the next waypoint in list and continue driving. The problem is: what do we do if for some odd reason the car turns a bit too much before it hit the waypoint (crashed into some other car maybe) - in this case it all can go berzerk faster as you can mumble "fuck". 
And then there are the other cars, having 4 cars chasing the same waypoint always ends up in a crash and then in missed waypoints ... the obvious solution is to prevent crashes, but that doesn't always work out like planed, too.

The first change I made, was to add 2 more waypoints and so having "lanes" on which the cars drive - this worked better. I created waypoints on the left, right and center of the road and give the cars a "lane" (ie: 0,1,2) on which the want to stay. As far as you want that all is good, but once you want to change lanes things get complicated again.

The current version uses a "floating" waypoint, it goes from the left side of the road to the right side and the AI cars use a float (0-1.0f) to see where they want to hit the wayoint (this also allows to use a "desiredLane" value and blend the current lane with the desired one over time). Now the AI cars cannot miss the waypoint any more, they just can miss their desired lane).

Phew, a lot of words, time for an image.

This is what I've been working on for the last couple of weeks (and prevented me to do any real work on MTR): animating and rendering a lot of small animations showing smoke and fire (sorry no further explanation just yet).

And with this, see you all next week.