THE LIGHT FANTASTIC
Lionhead is evidently proud of its bespoke global illumination system, which it developed internally once it became clear that Unreal Engine 4’s original setup wasn’t quite good enough for the needs of the studio’s artists. “Unreal 4 has been really good in terms of quality and efficiency and material work,” lead engine programmer Ben Woodhouse tells us. ”But we wanted all the lighting in
Legends to be dynamic to give us a lot of variation, so that we could change the time of day, and have shots with lots of lights in. So we wrote a system based on our LPV [light propagation values] and we’re using that now. Even the bounce lighting that comes off objects is dynamic as well.”
“It also makes it easier for us to make the characters and the world sit together easily,” explains art director Kelvin Tuite. “So we don’t get that thing where it feels like the characters are cut out from the world because they’re using a different lighting model.” The other benefit is increased flexibility: artists can simply take a level and move the position of the sun and adjust the time of day to quickly change its look and feel, with the results displayed in real time.
It means some of the usual tension between technicians and game artists is resolved, particularly with Microsoft having opened up to Xbox One developers the GPU power formerly reserved for Kinect and apps. “Anything freed up is something that we’ll gobble up in some way or another!” Tuite laughs. “Everything an artist does challenges performance. But, yeah, it’s absolutely helped.”
“There’s a lot more we can do with the Xbox GPU with physics simulations and that kind of thing,” Woodhouse says, “so we really want to push some of that.”
While other developers might use the tech to produce an ultra-detailed look, Tuite regards the physically based materials and the new global illumination – since integrated into Unreal Engine 4 itself – simply as tools to help augment the game’s illustrative style. “We’re not trying to [render] every pore on everyone’s skin; that’s not what we’re going for. Those fronds of grass will look like they’ve been painted down with a brush, not like they’ve been grown from fractals.”
And then comes the sprinkling of magic. Light sources aren’t just restricted to the sun, but will also pop into and out of existence along with the spells cast by various heroes. Such powers often have dramatic effects, but Tuite is aware that spectacle shouldn’t impact readability. “We still have that challenge ahead of us. Some characters have got huge visual effects [at the moment], which are not necessarily beneficial to the other characters while they’re playing. We want the magic to feel really powerful and cool but not to the extent that it’s hindering you or other players. Gameplay is king – if anything is obscured in some way, we’ll dial it back. It’s got to look nice! But playability is the key.”