Tables

Table 3: Predefined surface shader variables

Name	Type	Description
Cs	color	Surface color
Os	color	Surface opacity
P	point	Surface position
dPdu	vector	Derivative of surface position along u
dPdv	vector	Derivative of surface position along v
N	normal	Surface shading normal
Ng	normal	Surface geometric normal
u,v	float	Surface parameters
du,dv	float	Change in surface parameters
s,t	float	Surface texture coordinates
L	vector	Incoming light ray direction
Cl	color	Incoming light ray color
Ol	color	Incoming light ray opacity
E	point	Position of the eye
I	vector	Incident ray direction
ncomps	float	Number of color components
time	float	Current shutter time
dtime	float	The amount of time covered by this shading sample
dPdtime	vector	How the surface position P is changing per unit time,
		as described by motion blur in the scene
Ci	color	Incident ray color
Oi	color	Incident ray opacity

Table 4: Predefined imager shader variables

Name	Type	Description
P	point	Pixel raster position
Ci	color	Pixel color
Oi	color	Pixel opacity
alpha	float	Fractional pixel coverage
ncomps	float	Number of color components
time	float	Shutter open time
dtime	float	The amount of time the shutter was open
Ci	color	Output pixel color
Oi	color	Output pixel opacity

Table 5: Predefined light source shader variables

Name	Description
P	Surface position on the light
dPdu	Derivative of surface position along u
dPdv	Derivative of surface position along v
N	Surface shading normal on the light
Ng	Surface geometric normal on the light
u,v	Surface parameters
du,dv	Change in surface parameters
s,t	Surface texture coordinates
L	Outgoing light ray direction
Ps	Position being illuminated
E	Position of the eye
ncomps	Number of color components
time	Current shutter time
dtime	The amount of time covered by this shading sample
Cl	Outgoing light ray color
Ol	Outgoing light ray opacity