Practical Algorithms for 3D Computer Graphics, 2nd Edition

11.2. CPU textures 473

Figure 11.14: A contour pattern which with some added turbulence and appropriate

blend of color could resemble a three-dimensional wood grain pattern.

11.2.9 Contours

The contour pattern illustrated in figure 11.14 is derived from the basic bozo

texture by passing it through a periodic function, in this case a sinusoid, and

then thresholding the result as follows:

Given the point of interest as a (u, v, w) coordinat e.

n

u,v,w

=

1

2

(1 + sin(2πf

q

fNoise(u, v, w))

i f (n

u,v,w

> (1.0 − t)) {

return the color of the contour

}

e ls e retur n the background

The parameter t governs how thick the contours appear and f

q

is a measu r e

that can be