Hello,

Thanks for your question here on the Community Forums!

You are correct, values are passed between OpticStudio and DLL with a data array, and this array contains all parameter data from the NSC editor and the ray data.

The DLL has two functions, as below:

• UserParamNames(): returns parameter and face group names
• UserObjectDefinition(): contains object definition

For the UserParamNames() function the data value passed to the DLL is as follows:

• Data <= 0: OpticStudio wants name of particular face (i.e. -1 => face 1)
• Data > 0: OpticStudio wants name of parameter names

On the other hand, for the UserObjectDefinition Function, the data would be the following:

• Data[1] value indicates what the DLL should compute
  • Data[1] = 0
    • Place total number of triangular facets in Data[10]
    • Indicate if object is volume or shell in Data[11]
    • Indicate if object is diffractive in Data[12]
  • Data[1] = 1: list of triangles that compose tessellation
    • triangle info placed in tri_list array
  • Data[1] = 2: ray intercept and normal vector (after iteration)
    • OpticStudio provides ray coordinates and direction cosines on tessellation; DLL must iterate to exact surface
    • DLL returns path length to exact surface and normal vector at surface intercept point
  • Data[1] = 3: polarization data
  • Data[1] = 4: default/safe parameter values
• Data[100] indicates the number of data parameters passed to the DLL
•  Data[100+] are the values in parameter cells:
  •  Data[101] = parameter 1, Data[102] = parameter 2, etc.
     

You may find further information about NSC object DLLs in the Help system at:
The Setup Tab > Editors Group (Setup Tab) > Non-sequential Component Editor > Non-sequential Geometry Objects > User Defined Object

and in this knowledgebase article:
Custom DLLs in OpticStudio: An overview of user-defined surfaces, objects, and other DLL types – Knowledgebase (zemax.com)
 

For further references, I am attaching a pdf that provides more details about the individual data parameters.

Finally, I would also suggest to take a look at the sample codes EllipticalVolume and HalfCylinder in the \Documents\Zemax\DLL\Objects folder.

Best,
Csilla