How to use the mdlElmdscr_copyParallel function?

Question

Hello every body 
 I'd like to use the mdlElmdscr_copyParallel function, but I don't know how to initialise some arguments. 
 this is the ptototype function:

int 
 mdlElmdscr_copyParallel

(

MSElementDescr** 
 outDscrPP ,

MSElementDescr* 
 inDscr ,

DPoint3d* 
 point ,

double 
 distance ,

DPoint3d* 
 normal

);

What should I put in point and normal. 
 
 Thanks.

Jon Summers · Accepted Answer

Unknown said: I'd like to copy the yellow rectangle, the distance is equal to 0.5 
 Point is a direction vector: try something like this: 
 DVec3d direction;
// MDL specifies metrics in Units of Resolution (UORs)
const double distance = mdlModelRef_getUorPerMaster (ACTIVEMODEL) * .5;
mdlVec_fromXY (&direction, distance , 0);