| 1207 |
|
0 |
| 1208 |
|
5+ nmA nmB s1 s2 .. sN |
| 1209 |
|
.DE |
| 1210 |
< |
The first two real arguments indicate the limits of the covered |
| 1210 |
> |
The first two real arguments indicate the extrema of the |
| 1211 |
|
spectral range in nanometers. |
| 1212 |
< |
Subsequent real values correspond to multipliers in each wavelength band, |
| 1213 |
< |
where the first band goes from nmA to nmA+(nmB-nmA)/N, and N is the |
| 1214 |
< |
number of bands (i.e., the number of real arguments minus 2). |
| 1215 |
< |
The nmA wavelength may be greater or less than the nmB wavelength, |
| 1216 |
< |
but they may not be equal, and their ordering must correspond to |
| 1217 |
< |
the ordering of the spectral values. |
| 1212 |
> |
Subsequent real values correspond to multipliers at each wavelength. |
| 1213 |
> |
The nmA wavelength may be greater or less than nmB, |
| 1214 |
> |
but they may not be equal, and their ordering matches |
| 1215 |
> |
the order of the spectral values. |
| 1216 |
|
A minimum of 3 values must be given, which would act |
| 1217 |
|
more or less the same as a constant RGB multiplier. |
| 1218 |
|
As with RGB values, spectral quantities normally range between 0 |
| 1249 |
|
pattern, similar to the colorfunc type. |
| 1250 |
|
.DS |
| 1251 |
|
mod specfunc id |
| 1252 |
< |
2+ sval funcfile transform |
| 1252 |
> |
2+ sfunc funcfile transform |
| 1253 |
|
0 |
| 1254 |
|
2+ nmA nmB A3 .. |
| 1255 |
|
.DE |
| 1256 |
|
Like the spectrum primitive, the wavelength range is specified |
| 1257 |
|
in the first two real arguments, and additional real values are |
| 1258 |
< |
accessible to the sval function. |
| 1258 |
> |
set in the evaluation context. |
| 1259 |
|
This function is fed a wavelenth sample |
| 1260 |
|
between nmA and nmB as its only argument, |
| 1261 |
|
and it returns the corresponding spectral intensity. |
| 1262 |
+ |
.LP |
| 1263 |
+ |
.UL Specdata |
| 1264 |
+ |
.PP |
| 1265 |
+ |
Specdata is like brightdata and colordata, but with more |
| 1266 |
+ |
than 3 specular samples. |
| 1267 |
+ |
.DS |
| 1268 |
+ |
mod specdata id |
| 1269 |
+ |
3+n+ |
| 1270 |
+ |
func datafile |
| 1271 |
+ |
funcfile x1 x2 .. xn transform |
| 1272 |
+ |
0 |
| 1273 |
+ |
m A1 A2 .. Am |
| 1274 |
+ |
.DE |
| 1275 |
+ |
The data file must have one more dimension than the coordinate |
| 1276 |
+ |
variable count, as this final dimension corresponds to the covered |
| 1277 |
+ |
spectrum. |
| 1278 |
+ |
The starting and ending wavelengths are specified in "datafile" |
| 1279 |
+ |
as well as the number of spectral samples. |
| 1280 |
+ |
The function "func" will be called with two parameters, the |
| 1281 |
+ |
interpolated spectral value for the current coordinate and the |
| 1282 |
+ |
associated wavelength. |
| 1283 |
+ |
If the spectrum is broken into 12 components, then 12 calls |
| 1284 |
+ |
will be made to "func" for the relevant ray evaluation. |
| 1285 |
+ |
.LP |
| 1286 |
+ |
.UL Specpict |
| 1287 |
+ |
.PP |
| 1288 |
+ |
Specpict is a special case of specdata, where the pattern is |
| 1289 |
+ |
a hyperspectral image stored in the common-exponent file format. |
| 1290 |
+ |
The dimensions of the image data are determined by the picture |
| 1291 |
+ |
just as with the colorpict primitive. |
| 1292 |
+ |
.DS |
| 1293 |
+ |
mod specpict id |
| 1294 |
+ |
5+ |
| 1295 |
+ |
func specfile |
| 1296 |
+ |
funcfile u v transform |
| 1297 |
+ |
0 |
| 1298 |
+ |
m A1 A2 .. Am |
| 1299 |
+ |
.DE |
| 1300 |
+ |
The function "func" is called with the interpolated pixel value |
| 1301 |
+ |
and the wavelength sample in nanometers, the same as specdata, |
| 1302 |
+ |
with as many calls made as there are components in "specfile". |
| 1303 |
|
.NH 3 |
| 1304 |
|
Mixtures |
| 1305 |
|
.PP |
