Graphics Reference
In-Depth Information
march within this cube volume. This would allow us to reflect anything outside
the screen as well with pixel perfect ray-tracing-like results. This technique, Hi-Z
Cube-Map Ray Tracing, is ongoing research and it will be published at a later
time.
Another expansion could be packet tracing. This is ongoing research also
and will be published at a later time. The basic idea is to group several rays
together and basically shoot a packet of rays, like a frustum. As we intersect
the coarse Hi-Z, we can refine/subdivide the packet and shoot several more rays.
This way we can quickly intersect coarse Hi-Z levels and then do fewer operations
as we travel, though this makes the implementation more complex and harder to
maintain and relies heavily on compute shaders. Grouping coherent rays should
give an excellent boost in performance.
One could also do tiled tracing, where each tile identifies the roughness value
of the scene. In case the entire tile is very rough, we can probably get away
with shooting fewer rays and extrapolating most of the pixel colors. This multi-
resolution handling should also give an excellent boost in speed, though again
this also relies heavily on compute shaders.
All of those topics are ongoing research and will be, as said before, published
at a later time if it makes it out of the research and development phase.
4.12 Acknowledgments
I would like to give my special thanks to my co-workers who supported me at EA
DICE—Mikael Uddholm, Rendering Engineer of
Mirror's Edge
, and Charles de
Rousiers, Rendering Engineer of
Frostbi te
—and to my leads for proofreading this
chapter, also at EA DICE—Jonas Aberg, Technical Director of
Mirror's Edge
,
and Daniel Johansson, Lead Software Engineer of
Mirror's Edge
.
I would also like to give my special thanks to the editors of
GPU Pro 5
—
Michal Valient of Guerilla Games and Wolfgang Engel of Confetti FX—and to
project editor Charlotte Byrnes of CRC Press.
Bibliography
[Autodesk 09] Autodesk. “General Utility Shaders.”
mental ray Architectural
maya/2011help/mr/shaders/architectural/arch util.html, 2009.
[Behc 10] Behc. “Box Projected Cubemap Environment Mapping.” http://www.
2010.
[Bjorke 07] Kevin Bjorke. “Image-Based Lighting.” In
GPU Gems
,editedby
Randima Fernando, Chapter 19. Upper Saddle River, NJ: Addison-Wesley,
2007.
