Similar to what function (vlax-curve-getclosestpointto curve wcspt) do with reference curve, the task is now to find point on surface that is closest to reference point in 3D space...
Here on picture I marked point from as center of red sphere and in attachment there is also DWG with the same describing the task - problem...
IMHO I don't think this could be solved by using ALISP, but rather some other approach...
As a result I am expecting operational function that can operate correctly for all 3D entities such as 3DSOLIDs, SURFACEs, REGIONs, BODY entities, NURBS SURFACEs and all 3D Modeler entities...
Thanks for reading, may the competition begin...
M.R.