The Chase

The Chase introduces a futuristic landscape which two characters power through on gravity-defying hover bikes. Their desperate, exhilarating ride hints at a deeper backstory of conflict and passion.

Here’s how we brought it to life.

Extreme character detail

As with all character-driven stories, the devil’s in the detail. That’s why we created each character with a whopping 40,000 vertices. This is an extraordinarily high polycount for characters, even by current-gen console and PC game standards. Each character’s face and body have multiple 2048x2048 textures for skin color, reflectivity, normal maps, etc.

Realistic skin

Did you notice the characters’ skin? We achieved exceptional realism by implementing sub-surface scattering (SSS) skin shaders which blur incoming lighting in screen-space, a process also known as screen space diffusion. We took a lot of what we learned in The Butterfly Effect and optimized it for mobile GPUs.

Linear space lighting approximation

Pretty much all modern console or PC games do gamma correction, however many mobile GPUs still do not support automatic gamma corrected (sRGB) reads and writes. To emulate sRGB we used gamma of 2 which allowed us to use square (multiplication with self) and square root operations which are much faster than calculating the power of 2.2, for example. We only corrected for skin pixels and for the crucial skin-shading third pass.

Part of our goal with this demo was to illustrate just how impressive backdrops can be on mobile platforms. To achieve this, we decided to go for a mobile-friendly atmospheric scattering system instead of just using a traditional distance fog. We simulated scattering in the air by taking the angle to the sun and the distance to the object into account. As a result The Chase can deliver an exceptionally large and open viewing environment with the visible object furthest from the camera being four kilometres away.

Using layers of flares allowed us to achieve a variety of effects such as:

• Anamorphic phenomena: where flares move on the horizontal or vertical axis due to the anamorphic shape of the lens.
• Internal shadowing: where the intensity of the flare is partially culled because of the internal occlusion of the head mount or the lens’ uneven reflectance.
• Light leaking: where the flare’s geometry is stretched at the edge of the screen to simulate a very bright light source outside the frame.