| 7 |
|
[ |
| 8 |
|
.B "\-g Nlog2" |
| 9 |
|
][ |
| 10 |
< |
.B "\-t pctcull |
| 10 |
> |
.B "\-t pctcull" |
| 11 |
> |
][ |
| 12 |
> |
.B "\-l maxlobes" |
| 13 |
|
] |
| 14 |
|
[ |
| 15 |
|
.B "bsdf.sir .." |
| 22 |
|
[ |
| 23 |
|
.B "\-g Nlog2" |
| 24 |
|
][ |
| 25 |
< |
.B "\-t pctcull |
| 25 |
> |
.B "\-t pctcull" |
| 26 |
|
][ |
| 27 |
|
.B "{+|-}forward" |
| 28 |
|
][ |
| 29 |
|
.B "{+|-}backward" |
| 30 |
|
][ |
| 31 |
< |
.B "\-e expr |
| 31 |
> |
.B "\-e expr" |
| 32 |
|
][ |
| 33 |
< |
.B "\-f file |
| 33 |
> |
.B "\-f file" |
| 34 |
|
] |
| 35 |
|
.B bsdf_func |
| 36 |
|
.SH DESCRIPTION |
| 66 |
|
the four components, and if the first component |
| 67 |
|
is isotropic, all components must be isotropic. |
| 68 |
|
A similar rule holds for anisotropic inputs. |
| 69 |
+ |
The |
| 70 |
+ |
.I \-l |
| 71 |
+ |
option may be used to specify the maximum number of lobes in any |
| 72 |
+ |
interpolated radial basis function. |
| 73 |
+ |
The default value is 15000, which generally keeps the interpolation tractable. |
| 74 |
+ |
Setting the value to 0 turns off this limit. |
| 75 |
|
.PP |
| 76 |
|
In the second invocation form, |
| 77 |
|
.I bsdf2ttree |
| 78 |
|
takes a functional specification of a BSDF. |
| 79 |
< |
The named function must accept 6 parameters corresponding to the |
| 79 |
> |
The named function should accept 6 parameters corresponding to the |
| 80 |
|
normalized incident and exiting vectors, respectively. |
| 81 |
|
By convention, these vectors point away from the surface, and a positive |
| 82 |
|
Z-component corresponds to the front side. |
| 83 |
|
The Y-component corresponds to the "up" orientation of the surface, |
| 84 |
|
as specified in the eventual scene description that references the XML |
| 85 |
|
output. |
| 86 |
+ |
If the function only takes 3 parameters, then the variables "Dx", "Dy", |
| 87 |
+ |
and "Dz" will be assigned to the reverse of the outgoing direction at |
| 88 |
+ |
each evaluation. |
| 89 |
+ |
(I.e., the vector will point into the surface and |
| 90 |
+ |
Dz will be negative on the front side.)\0 |
| 91 |
+ |
This simplifies conversion of functional BSDF specifications using the |
| 92 |
+ |
legacy material primitives "plasfunc", "metfunc", and "transfunc". |
| 93 |
|
.PP |
| 94 |
|
The function is defined by one or more |
| 95 |
|
.I \-e |
