9.5.2

878 • CHAPTER 18
THE SHADERS • 879
Chan Lum
This shader was kindly supplied to us by “Naam” (www.happyship.com). ChanLum creates an effect
similar to SubSurface Scattering (see Advanced Render), the difference being that the ChanLum
shader’s effect takes place on the object surface. A good comparison would be to that of a peach,
whose surface is furry, somewhat blurred.
The ChanLum shader is designed for use in the “Luminance” channel. Simply load the shader, dene
a color that should be blended into the object’s color and set “Mix Mode” to “Multiply”. This shader
can also be used in other channels, e.g. the “Color” channel – just make sure“Mix Mode” is always
set to “Multiply”.
Of course the ChanLum shader can also be used in conjunction with a texture. “Layer” or “Fusion”
can be used. In both cases, both the “Mix Mode” and the mixing of the ChanLum shader with the
texture must be set to “Multiply”.
Note:
If you already have the original ChanLum plugin from HappyShip installed on
your system, it must be removed. Otherwise, you will encounter problems!
How ChanLum Works
 The example above illustrates what happens when a normal surface is rendered. For a point on the
surface (P), the angles (a) between the surface and all light sources in the scene will be ascertained.
These angles will then by analyzed by such lighting models as Phong or Oren Nayar, which will
determine how shading will look based on the lighting.