Practical Algorithms for 3D Computer Graphics, 2nd Edition

478 11. Algorithms for procedural textures

//Given the p o int of interest as a (u, v, w) coordinate.

//Displace the s a mp lin g point (u, v, w) by obtaining a turbulence vector ∆p

vTurbulence(∆p, u, v, w, )

u

′

= u + t∆p

u

v

′

= v + t∆p

v

w

′

= w + t∆p

w

//Sample the nois e function at (u

′

, v

′

, w

′

) and blend colors:

n = fNoise(u

′

, v

′

, w

′

)

i f (n < 0.5) //return the background color

e ls e i f (n < 0.6) {

//Blend to whit e from background: B

f = 10(n − 0.5)

r = r + f (1 − B

r

)

g = g + f (1 − B

g

)

b = b + f (1 − B

b

)

}

e ls e {

//Blend to gray:

f = 1 − 5(n − 0.6)

r = fr

g = f g

b = f b

}

Listing 11.8: Procedure to create the texture illus tr a t ed in figure 11.18. The parameter ...