Fin textures for real-time painterly aesthetics

We present a novel method for real-time stylized rendering in video games. Recent advances in painterly character authoring and rendering allow artists to create characters represented by 3D geometry as well as 3D paint strokes embedded on and around that geometry. The resulting 3D paintings are rendered in screen space using special-purpose offline rendering algorithms to achieve a unique painterly style. While providing novel styles for offline rendering, existing techniques do not support real-time applications. In this paper, we propose a method to interactively render these complex 3D paintings with a focus on character animation in video games. After observing that off-surface paint strokes can be interpreted as volumetric data in the proximity of 3D meshes, we review existing volumetric texture techniques and show that they are not adapted to paint strokes, which can be sparse and have a significant structure that should be preserved. We propose a method based on fin textures in which mesh edges are extended orthogonally off the surface and textured to replicate the results of the custom offline rendering method. Our algorithm uses a per-pixel normal calculation in order to fade in fin textures along boundary views. Our results demonstrate real-time performance using a commodity game engine while maintaining a painterly style comparable to offline methods.