NAMEhtrdr-materials - list of materials used by the ground geometry in htrdr(1)
A htrdr-materials file lists the materials that can be used by the ground geometry provided through a htrdr-obj(5) file to the htrdr(1) program. Each line of the file gives the name of the material. For opaque materials the material name is followed by the path toward the mrumtl(5) file storing the spectral properties of its associated Bidirectional Reflectance Distribution Function. Furthermore, the temperature of the material must be defined too.
The material name can be composed of any characters excepted for spaces and tabulations. The path toward the mrumtl(5) file must be a valid path relative to the file system.
Characters behind the hash mark (#) are considered as comments and are thus ignored. Empty lines, i.e. lines without any characters or composed of spaces and tabulations, are simply skipped.
<htrdr-materials> ::= <material> [ <material> ... ] <material> ::= <name> <properties> <name> ::= STRING <properties> ::= none | <mrumtl-path> <temperature> <mrumtl-path> ::= PATH <temperature> ::= REAL # In Kelvin
The following file lists 3 materials. The first one named grass has its spectral BRDF defines in the A001.mrumtl file. The second one is named sand and has its spectral properties saved in the B002.mrumtl file. Both materials have a temperature of 300 Kelvin. The last material is a semi-transparent material named air with no additionnal properties defined in this file.
grass /opt/materials/A001.mrumtl 300 sand /opt/materials/B002.mrumtl 300 air none