Red Brick Games

Work continues on Orcs vs. Martians. Today I got RTS-style fog of war working with Torque. I’m pretty excited about this, since I wasn’t sure I could get Torque to do fog of war. Torque continues to show itself to be a flexible tool.

For anyone who doesn’t know, fog-of-war refers to the way the world starts out dark, and is gradually illuminated as your units explore the map. Parts of the world that have been explored, but that are not currently in view, are usually rendered slightly greyed. FOW adds a lot of fun to an RTS game, because you have to explore to find resources and enemies’s bases. You also aren’t too sure what’s going on in areas that you can’t directly see.

Screenshot:

To get the fog of war effect, I am modifying Torque’s TerrainBlock alpha maps at run-time. To get the darkening effect, I added a new terrain material that is solid black. If terrain is unexplored, I simply set the black material to 99% and reduce the grass, sand, etc. materials to 1%. For the slightly-grey effect, I just set the black material to about 25% and the others to 75%. Then there’s a special function you have to call to tell Torque that you’ve changed the alpha maps. That’s pretty much it. Not too complicated, in retrospect.

Performance seems pretty decent, too. The worst case I saw when updating the fog of war took 6.5 milliseconds. Not bad, since the FOW only needs updating once a second or so.