Graphics Reference
In-Depth Information
the previous frames already contain the reflections. Research and development
techniques currently being developed will be mentioned, such as packet tracing
for grouping several rays together into a packet and then refining/subdividing
and shooting smaller ray packets once a coarse intersection is found. Another
direction for future research that will be mentioned is screen-space tile-based
tracing where if an entire tile contains mostly rough surfaces we know we can
shoot fewer rays because the result will most likely be blurred, thereby gaining
major performance, which gives us more room for other types of calculations for
producing better images.
Finally timers will be shown for PCs. For the PC we will use both NVIDIA-
and AMD-based graphics cards. Before we conclude the chapter, we will also
mention some future ideas and thoughts that are being currently researched and
developed.
This novel and production-proven approach (used in
Mirror's Edge
), pro-
posed in this chapter guarantees maximum quality, stability, and good perfor-
mance for computing local reflections, especially when it is used in conjunction
with the already available methods in the game industry such as local cube-maps
[Bjorke 07, Behc 10]. Specific attention is given to calculating physically accurate
glossy/rough reflections matching how the stretching and spreading of the reflec-
tions behave in real life from different angles, a phenomenon caused by micro
fractures.
4.2 Introduction
Let's start with the actual definition of a reflection:
Reflection
is the change in direction of a wave, such as a light or sound
wave, away from a boundary the wave encounters. Reflected waves
remain in their original medium rather than entering the medium they
encounter. According to the
law of reflection
, the angle of reflection
of a reflected wave is equal to its angle of incidence (Figure 4.1).
Reflections are an essential part of lighting; everything the human eye per-
ceives is a reflection, whether it's a specular (mirror), glossy (rough), or diffusive
Normal
Viewer
θ
θ
Relection
j
i
i
=
j
Mirror
Figure 4.1.
Law of reflection states that incident angle
i
equals reflection angle
j
.
