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Tank

One of the best customers for Tectrix VR was the US military. After much prodding we eventually got around to making a military themed game. The very first prototype, now probably lost to posterity, was a simple networked world with a bare mottled terrain, WWII-style green motorbikes, and funny arcing grenades. If you hit another bike with a grenade, they would get blasted into the air, but they weren't otherwise damaged after landing. As befits lost prototypes, this might have been the most fun of all the variations that followed.

The official design was a fairly complex Battlefield 1942 style team shooter, with helicopters and tanks, territory, flags, an interesting complex terrain, bouncy tank physics, etc. However, partway through production we drastically downsized, and had to scale back our ambitions to still get the game out the door.

So, when in doubt, raid the classics: the final product resembles a 3D treatment of Combat for the Atari 2600, with a heavy influence of Battlezone. The gameplay is pretty fun, though not super deep. The tanks shoot rockets, that have some nice launching effects. The walls and trees and stuff are destructible, and the orange barrels are explosive and can take out barriers as well as other tanks. It takes four direct hits to kill a tank, and there are ammo and repair powerups that appear at random times at certain places in the maps.

There were three maps; the game automatically cycled from one map to the next every couple of minutes. The play area of all the maps was perfectly flat, to avoid complications in targeting and navigation.

The first map was a mostly barren plain with some explosive barrels, rectangular blocky barriers, and a few power-up spots. The second map was chaotic and a lot of fun, with trees and explosives randomly scattered around. The third map was maze-like, with a lot of barriers.

Growing up as a fan of Battlezone, I always wanted to drive into the mountains in the background. As a sort of tribute, we set up an easter egg in Tank: in the third level, one of the tank traps that borders the play area is actually destructible. It's near one of the corners; I don't remember exactly which one it is. Anyway, you blast it away, and then you can drive out of the play area and up into the surrounding hills. We set up a little grove of signs out there, with the game credits.

Tech note: the terrain textures were based on surface-caching, an idea borrowed from John Carmack / Quake1 via Mike Abrash's lectures. There was a low resolution lightmap, a polygonal representation of the roads and other surface types, and a set of surface-type textures, which were rendered on demand into a modest-size (software) texture cache. If I recall correctly, the resolution of the textures was view-dependent; i.e. the more distant chunks of terrain used lower resolution renderings of the same source data. The terrain geometry was made of fixed-sized square chunks though. Sadly, for gameplay and schedule reasons we got rid of the varying terrain of earlier iterations so you don't really get the full effect of the lightmapping.

This all replaced the tricky (and non-lighted) system from Rocky vs the Firebugs, which split the terrain into polygons along surface-type boundaries.

Anyway, this was my introduction to (practical) LOD; later I would combine these ideas with quadtrees & geometry to get the Soul Ride terrain engine, and after that, Chunked LOD.

Some pics:

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