标题: An Efficient Alias-free Shadow Algorithm for Opaque and Transparent Objects [打印本页] 作者: 晃晃 时间: 2011-12-28 09:36 标题: An Efficient Alias-free Shadow Algorithm for Opaque and Transparent Objects An Efficient Alias-free Shadow Algorithm for Opaque and Transparent Objects
using per-triangle Shadow Volumes
Erik Sintorn Ola Olssony Ulf Assarssonz
Chalmers University Of Technology Chalmers University Of Technology
Chalmers University Of Technology
Abstract
This paper presents a novel method for generating pixel-accurate
shadows from point light-sources in real-time. The new method is
able to quickly cull pixels that are not in shadow and to trivially ac-
cept large chunks of pixels thanks mainly to using the whole trian-
gle shadow volume as a primitive, instead of rendering the shadow
quads independently as in the classic Shadow-Volume algorithm.
Our CUDA implementation outperforms z-fail consistently and sur-
passes z-pass at high resolutions, although these latter two are hard-
ware accelerated, while inheriting none of the robustness issues as-
sociated with these methods. Another, perhaps even more impor-
tant property of our algorithm, is that it requires no pre-processing
or identification of silhouette edges and so robustly and efficiently
handles arbitrary triangle soups. In terms of view sample test and
set operations performed, we show that our algorithm can be an or-
der of magnitude more efficient than z-pass when rendering a game-
scene at multi-sampled HD resolutions. We go on to show that
the algorithm can be trivially modified to support textured, semi-
transparent and colored semi-transparent shadow-casters and that
it can be combined with either depth-peeling or stochastic trans-
parency to also support transparent shadow receivers. Compared
to recent alias-free shadow-map algorithms, our method has a very
small memory footprint, does not suffer from load-balancing issues,
and handles omni-directional lights without modification. It is eas-
ily incorporated into any deferred rendering pipeline and combines
many of the strengths of shadow maps and shadow volumes.
