| 1484 |
|
<p> |
| 1485 |
|
The first two real arguments indicate the extrema of the |
| 1486 |
|
spectral range in nanometers. |
| 1487 |
< |
Subsequent real values correspond to multipliers in at each wavelength. |
| 1487 |
> |
Subsequent real values correspond to multipliers at each wavelength. |
| 1488 |
|
The nmA wavelength may be greater or less than nmB, |
| 1489 |
|
but they may not be equal, and their ordering matches |
| 1490 |
|
the order of the spectral values. |
| 1540 |
|
|
| 1541 |
|
<pre> |
| 1542 |
|
mod specfunc id |
| 1543 |
< |
2+ sval funcfile transform |
| 1543 |
> |
2+ sfunc funcfile transform |
| 1544 |
|
0 |
| 1545 |
|
2+ nmA nmB A3 .. |
| 1546 |
|
</pre> |
| 1548 |
|
<p> |
| 1549 |
|
Like the spectrum primitive, the wavelength range is specified |
| 1550 |
|
in the first two real arguments, and additional real values are |
| 1551 |
< |
accessible to the sval function. |
| 1551 |
> |
set in the evaluation context. |
| 1552 |
|
This function is fed a wavelenth sample |
| 1553 |
|
between nmA and nmB as its only argument, |
| 1554 |
|
and it returns the corresponding spectral intensity. |
| 1555 |
+ |
|
| 1556 |
+ |
<dt> |
| 1557 |
+ |
<a NAME="Specdata"> |
| 1558 |
+ |
<b>Specdata</b> |
| 1559 |
+ |
</a> |
| 1560 |
+ |
|
| 1561 |
+ |
<dd> |
| 1562 |
+ |
Specdata is like brightdata and colordata, but with more |
| 1563 |
+ |
than 3 specular samples. |
| 1564 |
+ |
|
| 1565 |
+ |
<pre> |
| 1566 |
+ |
mod specdata id |
| 1567 |
+ |
3+n+ |
| 1568 |
+ |
func datafile |
| 1569 |
+ |
funcfile x1 x2 .. xn transform |
| 1570 |
+ |
0 |
| 1571 |
+ |
m A1 A2 .. Am |
| 1572 |
+ |
</pre> |
| 1573 |
+ |
|
| 1574 |
+ |
<p> |
| 1575 |
+ |
The data file must have one more dimension than the coordinate |
| 1576 |
+ |
variable count, as this final dimension corresponds to the covered |
| 1577 |
+ |
spectrum. |
| 1578 |
+ |
The starting and ending wavelengths are specified in "datafile" |
| 1579 |
+ |
as well as the number of spectral samples. |
| 1580 |
+ |
The function "func" will be called with two parameters, the |
| 1581 |
+ |
interpolated spectral value for the current coordinate and the |
| 1582 |
+ |
associated wavelength. |
| 1583 |
+ |
If the spectrum is broken into 12 components, then 12 calls |
| 1584 |
+ |
will be made to "func" for the relevant ray evaluation. |
| 1585 |
+ |
|
| 1586 |
+ |
<dt> |
| 1587 |
+ |
<a NAME="Specpict"> |
| 1588 |
+ |
<b>Specpict</b> |
| 1589 |
+ |
</a> |
| 1590 |
+ |
|
| 1591 |
+ |
<dd> |
| 1592 |
+ |
Specpict is a special case of specdata, where the pattern is |
| 1593 |
+ |
a hyperspectral image stored in the common-exponent file format. |
| 1594 |
+ |
The dimensions of the image data are determined by the picture |
| 1595 |
+ |
just as with the colorpict primitive. |
| 1596 |
+ |
|
| 1597 |
+ |
<pre> |
| 1598 |
+ |
mod specpict id |
| 1599 |
+ |
5+ |
| 1600 |
+ |
func specfile |
| 1601 |
+ |
funcfile u v transform |
| 1602 |
+ |
0 |
| 1603 |
+ |
m A1 A2 .. Am |
| 1604 |
+ |
</pre> |
| 1605 |
+ |
|
| 1606 |
+ |
<p> |
| 1607 |
+ |
The function "func" is called with the interpolated pixel value |
| 1608 |
+ |
and the wavelength sample in nanometers, the same as specdata, |
| 1609 |
+ |
with as many calls made as there are components in "specfile". |
| 1610 |
|
|
| 1611 |
|
</dl> |
| 1612 |
|
|
