Anatomy of an explosion

Videogames love a good explosion, but how are these spectacular effects designed?

Explosions are some of gaming’s most dazzling effects. Ever since Doom’s toxic barrels let players turn demons into soup, developers have striven to make explosions bigger, more spectacular, and more dynamic. Today, explosions appear in all sorts of forms for all sorts of purposes, whether it’s starting a revolution in Just Cause, or triggering a tactical chain reaction in Divinity: Original Sin. In a matter of moments, explosions can change dramatically in size, shape, and color. They can be triggered by the player in all kinds of different ways, and radically alter the existing game state. But how do development studios actually tackle these stunning, violent and oh-sofleeting effects?

1 ParticlesThe core of any explosion is the game’s particle system. Originally, explosions were composed of sprite animations, but today’s explosions combine animation with particle simulation, resulting in explosions that respond dynamically to other in-game elements, such as weather.2 V i s u a l i z at i onEvery explosion is different. The JustCause team starts by referencing real-world explosions. “A lot of time is spent tweaking the timing, animation, and colors of an explosion to make sure that it’s impressive and readable both close up and at a distance,” says VFX artist Chris Judkins.3 AudioThe sound of an explosion is just as important as how it looks. Audio effects are also based upon real-world samples, mixed by a sound engineer to suit the game. They then need to be synchronized to the in-game effects, and balanced so that they appear to be coming from the right location.4 Sy s t e msAlongside how they look and sound, explosions in games influence the environment immediately around them. “Explosions are also tied into our physics system, so that the force of the explosion pushes and breaks things like buildings or trees around it,” Judkins explains.