Generating Traffic Patterns In A Procedural City news

Hey guys,

I'll describe some of the things I'm coding to achieve proper traffic patterns, required by the procedural cities in my game 'Just Death' [ JustDeath.com ]. This won't talk about the gameplay, physics, rendering, or any other systems of the project.

The only input to my procedural city generation system is a set of splines. The input splines are imported into my engine via ( scalable vector graphics format ) .svg file.

I've spent about 3 months building this game, on my own custom engine, you can read about it in this thread where I've posted about 50 updates showing all the progress [ Radioactivesoftware.com ]. I'll be sure to post more updates here as well! The game is still in a PRE-ALPHA state :-)

Ok lets get started...

First off here are a few images of the procedural cities I've created without and kind of debug output...

The first thing I wanted to do, in order to determine what lanes can connect with eachother - was to differentiate the North/South and East/West roads from eachother. The determination of a lane's general direction can be done with a fabs(X), fabs(Z) compare, to determine the major axis (of the normalized forward vector on the road's spline at that point), after that making E/W & N/W depends how you've setup your game engine. You want to do all these calculations in absolute world space, not any kind of local or tangent space down the road's spline path.

Here is a debug output image just showing the N/S and E/W traffic patterns as different colors.

Here is an image of the final result... I'll describe it in more depth below.

For a breakdown of the image above, consider the following ruleset, which is coded into the "intersection traffic controllers" ( that's just what I call the state machine and associated data structures created to represent a group of traffic lights) in my game engine:

Color Key
---------------
North = WHITE
East = GREEN
South = RED
West = BLUE

Traffic Controller Rules
---------------
To Go Straight:
RED-> RED
BLUE->BLUE
GREEN->GREEN
WHITE->WHITE

To Turn Right:
RED->BLUE
BLUE->WHITE
WHITE->GREEN
GREEN->RED

To Turn Left:
WHITE->BLUE
GREEN->WHITE
RED->GREEN
BLUE->RED

The final steps are to animate the in-game entities. There are other AI systems I use for more active objects - but for meandering civilians and vehicles I feel this "rail" system will suffice, until they are disturbed by the players.

For more information please visit JustDeath.com

Thanks!

- Dan
RadioactiveSoftware.com
dgreen@radioactive-software.com

P.S. Here are some other cool screenshots...

How the traffic looks from above in the city...

Lead Sled tearing it up, directly controlled by the player/user ;-)

Vigilante1 running in the city.

The elevated train in the city.

View from the back lot of a car wash.