Animation in Defense Grid
01/04/2010 by Adam Crockett
In this diary, I’ll be discussing aspects of the animation process for our tower defense title, Defense Grid: The Awakening.
The visual tone of the game was set by the various artists involved. This was done in a very collaborative environment – typical of game development at Hidden Path. We discussed and decided how the towers and creatures should move, and what sort of impact the animations should have.
In the game, the player character erects defensive towers from predefined slots in each level. Since we wanted to preserve the fundamental strategy of tower positioning, we didn’t want to have towers move around like characters, but we did want them to raise, lower, attack, and scan for the next target. We also planned special idle motions, and reload sequences, but most of the towers’ animation ‘zing’ is in the way they raise and lower, mechanically blossoming into death- dealing machines of doom. As we were starting to spec out some of our planned idles, T.J., one of the programmers, devised a procedural way for the turrets to “scan” for the next target. I was happy enough with the result to scratch most of the idle animations off the list. It was much less repetitive and more convincing than a looping idle animation created by an artist. Players will still see a standard idle here and there, such as a rotating radar dish, but most were replaced by T.J.’s great solution.
Accommodating the procedural motion wasn’t without its challenges – it meant re-rigging some of the towers to have yaw and pitch bones that the programmers could control (even in instances where a tower did not yaw or pitch!) but it was ultimately worth it, and I still love the way the towers all look around separately, searching for their next unlucky victim.
The aliens consist of the invading hordes intent on robbing the player of his precious power cores. They appear in increasingly difficult waves made up of different types of creatures with different stats. They move intently, focused on their goal, undeterred by the slaughter into which they march.
As models were completed, I began rigging the most complex one first -- the Juggernaut. We used 3d Studio Max‘s biped rig, posed as a quadruped. After rigging and skinning were completed, I created the first walk and death cycles to set the look and feel for our animation team. For additional direction, I tweaked the animation timing to work appropriately with the pacing of game play. The animation crew took it from there.
Though we started with a more complex list that included lots of animations, gameplay evolved such that we narrowed the list down to basically walking and dying. Those two animations had to convey each alien’s personality. Differentiating was a difficult task. Each alien has a couple of death animations, for variety, but the walks were pretty standard and so presented a tougher problem. To solve it, we added “leans” that we blended into their animations as the aliens turned corners. That added a lot to an otherwise unremarkable animation. I was very pleased with the way the alien animations turned out. Of course, I’m never completely satisfied. If we had additional time and budget, I would have liked to see the deaths have a bit more inertia, but they definitely convey what they need to with a lot of character from game view.
Overall, I’m really happy with the animation in Defense Grid. I think it is a substantially better experience than what other tower defense games have to offer. I still get giddy watching the towers unfold, and it’s always satisfying to watch a particularly tough alien finally crumple to the ground. I hope you enjoy playing Defense Grid: The Awakening, and thanks for reading!