You may have seen Ray Harryhausen credited with Technical Effects (meaning special effects) for his amazing stop-motion animation in movies like Mighty Joe Young, It Came From Beneath The Sea, and The Beast From 20,000 Fathoms. Well, this column isn't really about special effects, just technical game details and behind-the-scenes programming stuff that we thought you might find interesting. We'll be updating it regularly, or whenever Lars thinks of something.
01/01/03: BREAKING UP IS HARD TO DO
Each building in TCFH has its own unique collapse animation, allowing buildings to be recognized by their rubble as well as letting us customize special building collapses. For example, we can have the giant donut on top of the LA donut shop roll around when hit by the monster, or the head fall of of a truck-stop dinosaur. Smashing buildings wouldn't be nearly so much fun if they all fell down exactly the same way...and it would be too easy to get lost in a city full of generic rubble.
I GO TO PIECES
I've been reworking the collapse process, because I wasn't satisfied with our original attempt many months ago (as often happens during the course of game development). The rubble piles looked too much like giant bird nests to me. But because we're a small team, we need to rely on automation as much as possible, or we'll kill ourselves with the tedious manual labor. So we wrote a custom script which "chops up" each 3D building model, adds dust and "internal" debris, converts it to a particle system, and animates it shattering and falling down. There's usually only a minimal amount of manual tweaking needing afterwards to fine-tune the look. After-effects like dust clouds, smoke, explosions, fire or even radiation are added by the game engine at runtime.
Unfortunately, the particle system in our 3D toolset didn't behave as we desired for the building's collapse and was dog slow [ Hey, isn't this term offensive to greyhounds? Ed.]. I ended up having to rewrite key portions of it to make the collapse look better, create a more "chunky" look, and run about 100x faster.
Here's a movie theater (San Francisco's Castro, to be exact), and the way the collapsed building's rubble used to look in the game (these are just the "before" and "after" frames):
Now here's the entire animation of the new collapse sequence. We think the resulting rubble is a lot more realistic: