Graphics Reference
In-Depth Information
5 Reflections
5.1 Introduction
In this chapter we explore two scenarios where lines reflect from lines and surfaces. The reflecting
lines can represent the path taken by a collection of photons or the trajectory of a small particle
when striking another line or surface. Once more we will discover that the vector equations
describing a 2D scenario apply equally well in a 3D scenario. We begin by calculating how a
2D ray bounces from a reflecting line.
5.2 A line reflecting off a line
The reflecting line is defined parametrically, and a second parametric line represents the
incoming ray striking the reflecting line. At the point of contact, reflection takes place obeying
the classical laws of reflection: i.e., the angle of reflection equals the angle of incidence, and the
normal, incident, and reflected rays lie in a common plane. Figure 5.1 illustrates this scenario.
Y
w
T
n
v
out
w
v
R
v
in
P
t
p
r
X
Figure 5.1.
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