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rd - set the diffuse reflectance for the current material


rd rho_d


Set the diffuse reflectance for the current material to rho_d using the current color to determine the spectral characteristics. This is the fraction of visible light that is reflected from a surface equally in all directions according to Lambert's law, and is often called the "Lambertian component." Photometric reflectance is measured according to v(lambda) response function of the 1931 CIE standard 2 degree observer, and assumes an equal-energy white light source. The value must be between zero and one, and may be further restricted by the luminosity of the selected color. (I.e. it is impossible to have a violet material with a photometric reflectance close to one since the eye is less sensitive in this part of the spectrum.)

The default diffuse reflectance is zero.


# An off-white paint with 70% reflectance
m flat_white70 =
		cxy .3632 .3420
	rd .70


c, ed, ir, m, rs, sides, td, ts