| 148 |
|
... |
| 149 |
|
</pre> |
| 150 |
|
|
| 151 |
+ |
<p> |
| 152 |
+ |
|
| 153 |
|
A comment line begins with a pound sign, `#'. |
| 154 |
|
|
| 155 |
|
<p> |
| 396 |
|
0 |
| 397 |
|
</pre> |
| 398 |
|
|
| 399 |
+ |
<p> |
| 400 |
|
If the modifier is "void", then surfaces will |
| 401 |
|
use the modifiers given in the original description. |
| 402 |
|
Otherwise, the modifier specified is used in their place. |
| 441 |
|
0 |
| 442 |
|
</pre> |
| 443 |
|
|
| 444 |
+ |
<p> |
| 445 |
+ |
|
| 446 |
|
If the modifier is "void", then surfaces will |
| 447 |
|
use the modifiers given in the original mesh description. |
| 448 |
|
Otherwise, the modifier specified is used in their place. |
| 537 |
|
4 red green blue maxrad |
| 538 |
|
</pre> |
| 539 |
|
|
| 540 |
+ |
<p> |
| 541 |
|
If maxrad is zero, then the surface will never be tested for shadow, although it may participate in an interreflection calculation. |
| 542 |
|
If maxrad is negative, then the surface will never contribute to scene illumination. |
| 543 |
|
Glow sources will never illuminate objects on the other side of an illum surface. |
| 609 |
|
n A1 A2 .. An |
| 610 |
|
</pre> |
| 611 |
|
|
| 612 |
+ |
<p> |
| 613 |
+ |
|
| 614 |
|
The new direction variables dx, dy and dz need not produce a normalized vector. |
| 615 |
|
For convenience, the variables DxA, DyA and DzA are defined as the normalized direction to the target light source. |
| 616 |
|
See <a HREF="#Function">section 2.2.1</a> on function files for further information. |
| 654 |
|
3 source1 mirror1>source10 mirror2>mirror1>source3 |
| 655 |
|
</pre> |
| 656 |
|
|
| 657 |
+ |
<p> |
| 658 |
|
Normally, only one source is given per mist material, and there is an |
| 659 |
|
upper limit of 32 to the total number of active scattering sources. |
| 660 |
|
The extinction coefficient, if given, is added the the global |
| 675 |
|
P(theta) = (1 - g*g) / (1 + g*g - 2*g*cos(theta))^1.5 |
| 676 |
|
</pre> |
| 677 |
|
|
| 678 |
+ |
<p> |
| 679 |
+ |
|
| 680 |
|
A perfectly isotropic scattering medium has a g parameter of 0, and |
| 681 |
|
a highly directional material has a g parameter close to 1. |
| 682 |
|
Fits to the g parameter may be found along with typical extinction |
| 691 |
|
0|3|6|7 [ rext gext bext [ ralb galb balb [ g ] ] ] |
| 692 |
|
</pre> |
| 693 |
|
|
| 694 |
+ |
<p> |
| 695 |
+ |
|
| 696 |
|
There are two usual uses of the mist type. |
| 697 |
|
One is to surround a beam from a spotlight or laser so that it is |
| 698 |
|
visible during rendering. |
| 847 |
|
<p> |
| 848 |
|
|
| 849 |
|
<dt> |
| 850 |
+ |
<a NAME="WGMDfunc"> |
| 851 |
+ |
<b>WGMDfunc</b> |
| 852 |
+ |
</a> |
| 853 |
+ |
|
| 854 |
+ |
<dd> |
| 855 |
+ |
WGMDfunc is a more programmable version of <a HREF="#Trans2">trans2</a>, |
| 856 |
+ |
with separate modifier paths and variables to control each component. |
| 857 |
+ |
(WGMD stands for Ward-Geisler-Moroder-Duer, which is the basis for |
| 858 |
+ |
this empirical model, similar to previous ones beside Ashik2.) |
| 859 |
+ |
The specification of this material is given below. |
| 860 |
+ |
<pre> |
| 861 |
+ |
mod WGMDfunc id |
| 862 |
+ |
13+ rs_mod rs rs_urough rs_vrough |
| 863 |
+ |
ts_mod ts ts_urough ts_vrough |
| 864 |
+ |
td_mod |
| 865 |
+ |
ux uy uz funcfile transform |
| 866 |
+ |
0 |
| 867 |
+ |
9+ rfdif gfdif bfdif |
| 868 |
+ |
rbdif gbdif bbdif |
| 869 |
+ |
rtdif gtdif btdif |
| 870 |
+ |
A10 .. |
| 871 |
+ |
</pre> |
| 872 |
+ |
|
| 873 |
+ |
<p> |
| 874 |
+ |
|
| 875 |
+ |
The sum of specular reflectance (<I>rs</I>), specular transmittance (<I>ts</I>), |
| 876 |
+ |
diffuse reflectance (<I>rfdif gfdif bfdif</I> for front and <I>rbdif gbdif bbdif</I> for back) |
| 877 |
+ |
and diffuse transmittance (<I>rtdif gtdif btdif</I>) should be less than 1 for each |
| 878 |
+ |
channel. |
| 879 |
+ |
|
| 880 |
+ |
<p> |
| 881 |
+ |
|
| 882 |
+ |
Unique to this material, separate modifier channels are |
| 883 |
+ |
provided for each component. |
| 884 |
+ |
The main modifier is used on the diffuse reflectance, both |
| 885 |
+ |
front and back. |
| 886 |
+ |
The <I>rs_mod</I> modifier is used for specular reflectance. |
| 887 |
+ |
If "void" is given for <I>rs_mod</I>, |
| 888 |
+ |
then the specular reflection color will be white. |
| 889 |
+ |
The special "inherit" keyword may also be given, in which case |
| 890 |
+ |
specular reflectance will share the main modifier. |
| 891 |
+ |
This behavior is replicated for the specular transmittance modifier |
| 892 |
+ |
<I>ts_mod</I>, which also has its own independent roughness expressions. |
| 893 |
+ |
Finally, the diffuse transmittance modifier is given as |
| 894 |
+ |
<I>td_mod</I>, which may also be "void" or "inherit". |
| 895 |
+ |
Note that any spectra or color for specular components must be |
| 896 |
+ |
carried by the named modifier(s). |
| 897 |
+ |
|
| 898 |
+ |
<p> |
| 899 |
+ |
|
| 900 |
+ |
The main advantage to this material over |
| 901 |
+ |
<a HREF="#BRTDfunc">BRTDfunc</a> and |
| 902 |
+ |
other programmable types described below is that the specular sampling is |
| 903 |
+ |
well-defined, so that all components are fully computed. |
| 904 |
+ |
|
| 905 |
+ |
<p> |
| 906 |
+ |
|
| 907 |
+ |
<dt> |
| 908 |
|
<a NAME="Dielectric"> |
| 909 |
|
<b>Dielectric</b> |
| 910 |
|
</a> |
| 965 |
|
tn = (sqrt(.8402528435+.0072522239*Tn*Tn)-.9166530661)/.0036261119/Tn |
| 966 |
|
</pre> |
| 967 |
|
|
| 968 |
+ |
<p> |
| 969 |
+ |
|
| 970 |
|
Standard 88% transmittance glass has a transmissivity of 0.96. |
| 971 |
|
(A <a HREF="#Patterns">pattern</a> modifying glass will affect the transmissivity.) |
| 972 |
|
If a fourth real argument is given, it is interpreted as the index of refraction to use instead of 1.52. |
| 998 |
|
4+ red green blue spec A5 .. |
| 999 |
|
</pre> |
| 1000 |
|
|
| 1001 |
+ |
<p> |
| 1002 |
+ |
|
| 1003 |
|
The function refl takes four arguments, the x, y and z |
| 1004 |
|
direction towards the incident light, and the solid angle |
| 1005 |
|
subtended by the source. |
| 1041 |
|
6+ red green blue rspec trans tspec A7 .. |
| 1042 |
|
</pre> |
| 1043 |
|
|
| 1044 |
+ |
<p> |
| 1045 |
+ |
|
| 1046 |
|
Where trans is the total light transmitted and tspec is the non-Lambertian fraction of transmitted light. |
| 1047 |
|
The function brtd should integrate to 1 over each projected hemisphere. |
| 1048 |
|
|
| 1070 |
|
A10 .. |
| 1071 |
|
</pre> |
| 1072 |
|
|
| 1073 |
+ |
<p> |
| 1074 |
+ |
|
| 1075 |
|
The variables rrefl, grefl and brefl specify the color coefficients for the ideal specular (mirror) reflection of the surface. |
| 1076 |
|
The variables rtrns, gtrns and btrns specify the color coefficients for the ideal specular transmission. |
| 1077 |
|
The functions rbrtd, gbrtd and bbrtd take the direction to the incident light (and its solid angle) and |
| 1116 |
|
4+ red green blue spec A5 .. |
| 1117 |
|
</pre> |
| 1118 |
|
|
| 1119 |
+ |
<p> |
| 1120 |
+ |
|
| 1121 |
|
The coordinate indices (x1, x2, etc.) are themselves functions of the x, y and z direction to the incident light, plus the solid angle |
| 1122 |
|
subtended by the light source (usually ignored). |
| 1123 |
|
The data function (func) takes five variables, the |
| 1284 |
|
0 |
| 1285 |
|
</pre> |
| 1286 |
|
|
| 1287 |
+ |
<p> |
| 1288 |
+ |
|
| 1289 |
|
The first modifier will also be used to shade the area leaving the antimatter volume and entering the regular volume. |
| 1290 |
|
If mod1 is void, the antimatter volume is completely invisible. |
| 1291 |
|
Antimatter does not work properly with the material type <a HREF="#Trans">"trans"</a>, |
| 1340 |
|
n A1 A2 .. An |
| 1341 |
|
</pre> |
| 1342 |
|
|
| 1343 |
+ |
<p> |
| 1344 |
+ |
|
| 1345 |
|
</dl> |
| 1346 |
|
|
| 1347 |
|
<p> |
| 1481 |
|
[spacing] |
| 1482 |
|
</pre> |
| 1483 |
|
|
| 1484 |
+ |
<p> |
| 1485 |
+ |
|
| 1486 |
|
or: |
| 1487 |
|
|
| 1488 |
|
<pre> |
| 1520 |
|
[spacing] |
| 1521 |
|
</pre> |
| 1522 |
|
|
| 1523 |
+ |
<p> |
| 1524 |
+ |
|
| 1525 |
|
or: |
| 1526 |
|
|
| 1527 |
|
<pre> |
| 1571 |
|
</pre> |
| 1572 |
|
|
| 1573 |
|
<p> |
| 1574 |
< |
The first two real arguments indicate the limits of the covered |
| 1574 |
> |
The first two real arguments indicate the extrema of the |
| 1575 |
|
spectral range in nanometers. |
| 1576 |
< |
Subsequent real values correspond to multipliers in each wavelength band, |
| 1577 |
< |
where the first band goes from nmA to nmA+(nmB-nmA)/N, and N is the |
| 1578 |
< |
number of bands (i.e., the number of real arguments minus 2). |
| 1579 |
< |
The nmA wavelength may be greater or less than the nmB wavelength, |
| 1491 |
< |
but they may not be equal, and their ordering must correspond to |
| 1492 |
< |
the ordering of the spectral values. |
| 1576 |
> |
Subsequent real values correspond to multipliers at each wavelength. |
| 1577 |
> |
The nmA wavelength may be greater or less than nmB, |
| 1578 |
> |
but they may not be equal, and their ordering matches |
| 1579 |
> |
the order of the spectral values. |
| 1580 |
|
A minimum of 3 values must be given, which would act |
| 1581 |
|
more or less the same as a constant RGB multiplier. |
| 1582 |
|
As with RGB values, spectral quantities normally range between 0 |
| 1629 |
|
|
| 1630 |
|
<pre> |
| 1631 |
|
mod specfunc id |
| 1632 |
< |
2+ sval funcfile transform |
| 1632 |
> |
2+ sfunc funcfile transform |
| 1633 |
|
0 |
| 1634 |
|
2+ nmA nmB A3 .. |
| 1635 |
|
</pre> |
| 1637 |
|
<p> |
| 1638 |
|
Like the spectrum primitive, the wavelength range is specified |
| 1639 |
|
in the first two real arguments, and additional real values are |
| 1640 |
< |
accessible to the sval function. |
| 1640 |
> |
set in the evaluation context. |
| 1641 |
|
This function is fed a wavelenth sample |
| 1642 |
|
between nmA and nmB as its only argument, |
| 1643 |
|
and it returns the corresponding spectral intensity. |
| 1644 |
|
|
| 1645 |
+ |
<dt> |
| 1646 |
+ |
<a NAME="Specdata"> |
| 1647 |
+ |
<b>Specdata</b> |
| 1648 |
+ |
</a> |
| 1649 |
+ |
|
| 1650 |
+ |
<dd> |
| 1651 |
+ |
Specdata is like brightdata and colordata, but with more |
| 1652 |
+ |
than 3 specular samples. |
| 1653 |
+ |
|
| 1654 |
+ |
<pre> |
| 1655 |
+ |
mod specdata id |
| 1656 |
+ |
3+n+ |
| 1657 |
+ |
func datafile |
| 1658 |
+ |
funcfile x1 x2 .. xn transform |
| 1659 |
+ |
0 |
| 1660 |
+ |
m A1 A2 .. Am |
| 1661 |
+ |
</pre> |
| 1662 |
+ |
|
| 1663 |
+ |
<p> |
| 1664 |
+ |
The data file must have one more dimension than the coordinate |
| 1665 |
+ |
variable count, as this final dimension corresponds to the covered |
| 1666 |
+ |
spectrum. |
| 1667 |
+ |
The starting and ending wavelengths are specified in "datafile" |
| 1668 |
+ |
as well as the number of spectral samples. |
| 1669 |
+ |
The function "func" will be called with two parameters, the |
| 1670 |
+ |
interpolated spectral value for the current coordinate and the |
| 1671 |
+ |
associated wavelength. |
| 1672 |
+ |
If the spectrum is broken into 12 components, then 12 calls |
| 1673 |
+ |
will be made to "func" for the relevant ray evaluation. |
| 1674 |
+ |
|
| 1675 |
+ |
<dt> |
| 1676 |
+ |
<a NAME="Specpict"> |
| 1677 |
+ |
<b>Specpict</b> |
| 1678 |
+ |
</a> |
| 1679 |
+ |
|
| 1680 |
+ |
<dd> |
| 1681 |
+ |
Specpict is a special case of specdata, where the pattern is |
| 1682 |
+ |
a hyperspectral image stored in the common-exponent file format. |
| 1683 |
+ |
The dimensions of the image data are determined by the picture |
| 1684 |
+ |
just as with the colorpict primitive. |
| 1685 |
+ |
|
| 1686 |
+ |
<pre> |
| 1687 |
+ |
mod specpict id |
| 1688 |
+ |
5+ |
| 1689 |
+ |
func specfile |
| 1690 |
+ |
funcfile u v transform |
| 1691 |
+ |
0 |
| 1692 |
+ |
m A1 A2 .. Am |
| 1693 |
+ |
</pre> |
| 1694 |
+ |
|
| 1695 |
+ |
<p> |
| 1696 |
+ |
The function "func" is called with the interpolated pixel value |
| 1697 |
+ |
and the wavelength sample in nanometers, the same as specdata, |
| 1698 |
+ |
with as many calls made as there are components in "specfile". |
| 1699 |
+ |
|
| 1700 |
|
</dl> |
| 1701 |
|
|
| 1702 |
|
<p> |
| 1729 |
|
n A1 A2 .. An |
| 1730 |
|
</pre> |
| 1731 |
|
|
| 1732 |
+ |
<p> |
| 1733 |
+ |
|
| 1734 |
|
Foreground and background are modifier names that must be |
| 1735 |
|
defined earlier in the scene description. |
| 1736 |
|
If one of these is a material, then |
| 1759 |
|
m A1 A2 .. Am |
| 1760 |
|
</pre> |
| 1761 |
|
|
| 1762 |
+ |
<p> |
| 1763 |
+ |
|
| 1764 |
|
<dt> |
| 1765 |
|
<a NAME="Mixpict"> |
| 1766 |
|
<b>Mixpict</b> |
| 1805 |
|
[spacing] |
| 1806 |
|
</pre> |
| 1807 |
|
|
| 1808 |
+ |
<p> |
| 1809 |
+ |
|
| 1810 |
|
or: |
| 1811 |
|
|
| 1812 |
|
<pre> |
| 1822 |
|
[spacing] |
| 1823 |
|
</pre> |
| 1824 |
|
|
| 1825 |
+ |
<p> |
| 1826 |
+ |
|
| 1827 |
|
</dl> |
| 1828 |
|
|
| 1829 |
|
<p> |
| 1868 |
|
cfunc(x) : 10*x / sqrt(x) ; |
| 1869 |
|
</pre> |
| 1870 |
|
|
| 1871 |
+ |
<p> |
| 1872 |
+ |
|
| 1873 |
|
Many variables and functions are already defined by the program, and they are listed in the file rayinit.cal. |
| 1874 |
|
The following variables are particularly important: |
| 1875 |
|
|
| 1884 |
|
arg(i) - i'th real argument |
| 1885 |
|
</pre> |
| 1886 |
|
|
| 1887 |
+ |
<p> |
| 1888 |
+ |
|
| 1889 |
|
For mesh objects, the local surface coordinates are available: |
| 1890 |
|
|
| 1891 |
|
<pre> |
| 1892 |
|
Lu, Lv - local (u,v) coordinates |
| 1893 |
|
</pre> |
| 1894 |
|
|
| 1895 |
+ |
<p> |
| 1896 |
+ |
|
| 1897 |
|
For BRDF types, the following variables are defined as well: |
| 1898 |
|
|
| 1899 |
|
<pre> |
| 1902 |
|
CrP, CgP, CbP - perturbed material color |
| 1903 |
|
</pre> |
| 1904 |
|
|
| 1905 |
+ |
<p> |
| 1906 |
+ |
|
| 1907 |
|
A unique context is set up for each file so |
| 1908 |
|
that the same variable may appear in different |
| 1909 |
|
function files without conflict. |
| 1958 |
|
DATA, later dimensions changing faster. |
| 1959 |
|
</pre> |
| 1960 |
|
|
| 1961 |
+ |
<p> |
| 1962 |
+ |
|
| 1963 |
|
N is the number of dimensions. |
| 1964 |
|
For each dimension, the beginning and ending coordinate values and the dimension size is given. |
| 1965 |
|
Alternatively, individual coordinate values can be given when the points are not evenly spaced. |
| 1988 |
|
... |
| 1989 |
|
</pre> |
| 1990 |
|
|
| 1991 |
+ |
<p> |
| 1992 |
+ |
|
| 1993 |
|
The ASCII codes can appear in any order. N is the number of vertices, and the last is automatically connected to the first. |
| 1994 |
|
Separate polygonal sections are joined by coincident sides. |
| 1995 |
|
The character coordinate system is a square with lower left corner at (0,0), lower right at (255,0) and upper right at (255,255). |
| 2177 |
|
OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 2178 |
|
SUCH DAMAGE. |
| 2179 |
|
</pre> |
| 2180 |
+ |
|
| 2181 |
+ |
<p> |
| 2182 |
|
|
| 2183 |
|
<hr> |
| 2184 |
|
|
