The 3D model of heliostat should be provided as obj-file.


Structure of obj-file
---------------------
The file should define a single object (o) with vertex (v) and normal (vn) buffers.
The different moving parts of heliostat should be marked as groups (g): 
Root,
Primary,
Secondary,
DrivePrimaryR
DrivePrimaryP,
DriveSecondaryS,
DriveSecondaryP.
Triangulation of faces (f) is necessary for ray tracing, but not for display.


Exporting from Blender
----------------------
The groups can be created as "Vertex Groups".
The export settings are:
"Selection only",
"Y Forward",
"Z Up",
"Write Normals",
"Polygroups",
"Keep Vertex Order".


Importing to Blender
--------------------
"Y Forward",
"Z Up",
"Keep Vertex Order",
"Poly Groups".
