Light Profiles

mi_api_lightprofile_begin
mi_api_lightprofile_end
mi_api_lightprofile_lookup

Light Profiles

Light profiles such as IES or Eulumdat are files provided by physical lamp vendors to specify the light emission characteristics of their products. The profile files can be read and preprocessed by mental ray, and access and measurement functions are supplied to shaders. The following API calls implement the lightprofile...end lightprofile blocks in .mi scene files, which attach a name to a profile that can be passed to shaders as an argument of type lightprofile.

mi_api_lightprofile_begin

    miLight_profile *mi_api_lightprofile_begin(
        char            *name)          /* name of light profile */

Begin the definition of a light profile named name, and return a pointer to the new light profile. The caller should set the following fields:

filename: the name of the profile file, as a tag of type miSCENE_STRING.
format: either miLP_STD_IES or miLP_STD_EULUMDAT.
base: always miLP_BASIS_HERMITE.
quality: the hermite degree, 1 or 3, 1 is default.
n_vert_angles, n_horz_angles: the number of measurement points interpolated from the mesh in the light profile file. If either is 0 (the default), mental ray will use the resolution in the profile file.
flags: if 0 (the default), use the sample order defined in the profile. If 1, force horizontal angles to grow clockwise when observed from zenith. If 2, force horizontal angles to grow counterclockwise when observed from zenith.

After all fields are defined, call mi_api_lightprofile_end.

mi_api_lightprofile_end

    miTag mi_api_lightprofile_end(void)

Completes the definition of the light profile.

mi_api_lightprofile_lookup

    miTag mi_api_lightprofile_lookup(
        char            *name)          /* symbolic profile name */

Returns the tag associated with the symbolic name of a light profile. This function is not required; it may be useful when defining shader parameter values for parameters of type lightprofile.