GPU-based responsive grass

Abstract

Large natural environments are often essential for todays computer games. Interaction with the environment is widely implemented in order to satisfy the player’s expectations of a living scenery and to help increasing the immersion of the player. Within this context our work describes an efficient way to simulate a responsive grass layer with todays graphics cards in real-time. Clumps of grass are approximated by two billboard representations. GPU-based distance maps of scene objects are employed to test for penetrations and for resolving them. Adaptive refinement is necessary to preserve the shape of deformed billboards. A recovering process is applied after the deformation which restores the original that is to say the undeformed and efficient shape. The primitives of each billboard are assembled during the rendering process. Their vertices are dynamically lit within an ambient occlusion based irradiance volume. Alpha-to-Coverage completes the illusion as it is used to simulate the semitransparent nature of grass.