Saturday, March 28, 2009

How to make Asymmetrical Board Game maps in Silverlight

Or, how I spent my evenings at MIX09 in Las Vegas.

Last year, I began looking into writing board games with an asymmetrical map boards. I started with Awful Green Things from Outer Space (AGTFOS), a classic beer and pretzels game by Tom Wham. I started with an alternate game board graphic I downloaded from

But, since the map is asymmetrical, there is no simple math function that, given an X,Y coordinate, would tell me what room in the spaceship I clicked on.

After a lot of googling, I found that boardgame programmers use a 2D array where every every element in the array corresponds to a pixel in the map image. Then set al the array elements to values that equal what room that pixel is in. This worked great, but it has a problem - No scaling. I could not scale the graphic and still know what room I was in.

WPF and Silverlight to the rescue!

So, as a proof of concept, I took a states map of the USA in SVG from Wikipedia and used ZamlTune to convert the SVG to XAML. Since all the elements in WPF are scalable and clickable, I was able to, with just a few lines of code, make the map aware of what element I was clicking and change its fill color.

That solved half of the problem of a asymmetrical board game map. The other issue is for movement and conflict. We need to know what states directly border the selected state. For this we need to go back to Comp Sci 350 - Data Structures. We need a graph.

Graphs have Vertexes and Edges. A vertex can be thought of as a location and the Edges as the roads to and from these locations. So, if we had a Graph with a vertex for each State and an edge to each bordering State, we could easily find out what States border each other.

Unlike previous silverlight examples I've posted, this one cannot be embeded since it needs to resize, so you need to open the link to run my example USA map. If we wanted to play Risk on a USA map, this would be a large positive step towards that goal.

As, you can see in the image the selected State is in Blue and the bordering States are in Light Blue. (Click on Image to Open The Silverlight Application)

Unfortunately the Graph object I wrote for this proof of concept is not nearly as full featured a Graph object as per my previous post.

And here is a zip file containing the entire Visual Studio 2008 Project.

1 comment:

Unknown said...

You zip file only contained the dlls. Sure would like to get the source code for this project.