Undusting the floppies the other day brought yet another “Wow !” moment … I was writing LISP code in 1991 ? And it certainly seems non-trivial stuff, at least to me.
Polygon tessellation (triangulation) and simillar “delicacies”. Those where the days of my heavy involvement with ACAD AutoLISP, vector graphics etc. Here is one example. The start of a polygon triangulation utility
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; ; 08.01.92 DBJ translated into RUN system ; dbjtri.lsp 25.09.91 DBJ created ; (setq function (lambda ( / plst pln Vmin) ( SETQ *ERROR* runerr ) ( SETVAR "CMDECHO" 0 ) ; GLOBALS (setq quad '() ; list of quad's trian '() ; list of triang's fset (ssadd) ; s-set for faces vlst10 '() ; list of vertices pFlag -1) ; polyline flag ( prompt "n*DBJTRI* Conversion of Polylines to faces ") ( SETQ pln (call "tri/getpln") ; get poly line list name plst (call '("tri/plnlst" pln)) ; make vLst10 from pline Vmin (call "tri/pxmin") ; index of V with Xmin in it xmin (car (nth Vmin vLst10)) ; xmin of Vlst10 ) ; setq ; Order the polygon in the right way by DBJ ! (if (< (call '("tri/aof3" ; if (nth (call '("tri/1left" Vmin vLst10)) vLst10) ; area (nth Vmin vLst10) ; of leftmost (nth (call '("tri/1from" Vmin vLst10)) vLst10); triangle ) ) ; is less 0) ; than 0 (setq vLst10 (reverse vLst10)) ; then reverse the polyline ! ) (call '("tri/layon" "3dface")) ; and on this layer (call '("tri/sp3tof" xmin )) ; do the glorious thing (call "tri/make3or4") ; make set of faces ... (princ) ) ; end DBJTRI lambda ) ; end Function set |
Now, this is what I might call “Gobsmacking”. I remember I was doing it and that it has worked, etc. But to explain it today, I think I would need to transform it first to e.g. JavaScript and then try and explain this code.
Update 2013-Aug-10
My (Auto)LISP legacy is now on github: