9.5.2

902 • CHAPTER 18
THE SHADERS • 903
Spectrum
The Spectrum gradient denes the colors for the spectral reexes.
Use CD Effect
If you enable this option, the shader is optimized for cylindrical surfaces and you can render wedge-
shaped, prismatic color effects, such as those seen on CD surfaces.
Width
Width denes how far the gradient spreads out.
Peak
Normally the entire rainbow colored spectrum is visible only if the angle between the light source
and the camera forms a straight line. Increasing the Peak value allows you to generate a larger color
spectrum.
W Factor
W Factor denes the starting point of the prismatic effect, based on the center of the surface. A value
of 1 makes the gradient start from the exact center of the surface. Values above 1 offset the gradient
away from the center, and values below 1 shift it more towards the center.
Diffuse Intensity
Diffuse Intensity controls the intensity of the actual spectral effect. Increasing the value results in
overblown colors.
Diffuse Variation
Diffuse Variation scatters the spectral effect by bringing in random colors from the gradient.
Front Side
Here you can dene how the spectral gradient is projected onto the surface, with reference to the
object coordinate system. If you can’t see the CD effect immediately, you probably need to adjust
this parameter.