ZP+: correct Z-pass stencil shadows
We present a novel algorithm for the rendering of hard shadows
cast by a point light source. The well-known Z-pass method for
rasterizing shadow volumes is not always correct. Our algorithm,
which we call ZP+, elegantly corrects Z-pass defects. ZP+
takes advantage of triangle strips and fast culling capabilities
of graphics hardware not available to conventional robust methods
like Z-fail. While Z-fail can be up to 80% slower than Z-pass,
our new method ZP+ is typically less than 10% slower than
Z-pass. Finally, we give a comparison of the three methods. When a
scene is geometry-bound, ZP+ is always faster than Z-fail. We
also explain why, in some situations, Z-pass (hence ZP+) is
surprisingly slower than Z-fail on more recent graphics hardware.
Images and movies
See also
Additional illustrations can be found in this document.
BibTex references
@InProceedings\{HHLH05, author = "Hornus, Samuel and Hoberock, Jared and Lefebvre, Sylvain and Hart, John C.", title = "ZP+: correct Z-pass stencil shadows", booktitle = "ACM Symposium on Interactive 3D Graphics and Games", month = "April", year = "2005", publisher = "ACM Press", organization = "ACM", url = "http://artis.inrialpes.fr/Publications/2005/HHLH05" }