Re: A style question



Rainer Joswig wrote:
In article <1172658813.746823.247380@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
"Tim Bradshaw" <tfb+google@xxxxxxxx> wrote:

Incidentally, I'm deeply disappointed in the quality of answers in
this thread. In the elder days there would have been at least a few
followups showing how to do this in the proper "FORMAT string
indistinguishable from line noise" way. No true CL programmer ever
uses any other construct when the problem can be solved with a
combination of FORMAT, LOOP & GO (FORMAT being always preferable,
obviously). There may yet be those reading cll who know this, though
I suspect they have all gone into the west now.


It is always a shock to me when I look at such code. I mean
many pages long functions full of GOs, two letter variables
and such (and zero comments). I cannot
believe that humans can write this code.

You refer of course to the Cello code to create a 3-D oblong button of variable thickness with rounded corners of variable radius:

(defun ix-render-oblong (lbox thickness baser slices stacks)
(unless slices (setq slices 0))
(unless stacks (setq stacks (if (zerop thickness)
0 (min 10
(max 1 ;; force 3d if nonzero thickness
(round (abs thickness) 2))))))
(when (eql (abs thickness) (abs baser))
(setf thickness (* .99 thickness)))
(trc nil "oblong" baser thickness etages)

(loop
with theta = (/ pi 2 slices)
with etages = stacks ;; french floors (etages) zero = ground floor
with lw/2 = (/ (r-width lbox) 2)
with lh/2 = (/ (r-height lbox) 2)
with bx = (- lw/2 baser)
with by = (- lh/2 baser)
for etage upto etages
for oe = 0 then ie
for ie = (unless (= etage etages)
(* (/ (1+ etage) etages)
(/ pi 2)))
for ii = (if (not ie)
0 ;; throwaway value to avoid forever testing if nil
(+ (* (abs thickness)
(- 1 (cos ie)))))

for ox = lw/2 then ix
for oy = lh/2 then iy
for oz = 0 then iz
for oc = (cornering baser slices) then ic
for ic = (when ie
(cornering (- baser ii) slices))
for ix = (- lw/2 ii)
for iy = (- lh/2 ii)
for iz = (when ie
(* thickness (sin ie)))

do (trc nil "staging" etage ie)


(gl-translatef (+ (r-left lbox) lw/2)(+ (r-bottom lbox) lh/2) 0)

(with-gl-begun ((if ie
gl_quad_strip
gl_polygon))

(loop for (dx dy no-turn-p)
in '((1 1)(-1 1)(-1 -1)(1 -1)(1 1 t))
;;for dbg = (and (eql dx 1)(eql dy 1)(not no-turn-p))
do (destructuring-bind (xyn0 ix0 iy0 ox0 oy0)
(cons (+ (if oc (/ theta 2) 0)
(ecase dx (1 (ecase dy (1 0)(-1 (/ pi -2))))
(-1 (ecase dy (1 (/ pi 2))(-1 pi)))))
(if oc
(case (* dx dy)
(1 (list (* dx ix)(* dy by)(* dx ox)(* dy by)))
(-1 (list (* dx bx)(* dy iy)(* dx bx)(* dy oy))))
(list (* dx ix)(* dy iy)(* dx ox)(* dy oy))))

;; --- lay-down start/only -------------
(when ie
(ogl-vertex-normaling ie xyn0 ix0 iy0 iz))
(ogl-vertex-normaling oe xyn0 ox0 oy0 oz)

(trc nil "cornering!!!!!!----------------" dx dy)
;; --- corner if slices and not just finishing strip

(unless no-turn-p
(trc nil "------ start ------------------" (length oc)(length ic))
(loop for (oxn . oyn) in oc
for icrem = ic then (cdr icrem)
for (ixn . iyn) = (car icrem)
for xyn upfrom (+ xyn0 theta) by theta
do (macrolet
((vtx (elev gx sx gy sy gz)
`(progn
(when (minusp (* dx dy))
(rotatef ,sx ,sy))
(ogl-vertex-normaling ,elev xyn
(incf ,gx (* dx ,sx))
(incf ,gy (* dy ,sy))
,gz))))
(trc nil "ocn icn" oxn oyn (car icrem))
(when icrem
(vtx ie ix0 ixn iy0 iyn iz))
(vtx oe ox0 oxn oy0 oyn oz)))))))
(gl-translatef (- (+ (r-left lbox) lw/2))
(- (+ (r-bottom lbox) lh/2)) 0)))

I always
think the author was some ugly 'Terminator' from the future,
though lately the Terminators seem to be blond and good looking.

Actually I was doing a rare transcription from a paper solution (where short variables saved pencil lead).

kt

--
Well, I've wrestled with reality for 35 years, Doctor, and
I'm happy to state I finally won out over it.
-- Elwood P. Dowd

In this world, you must be oh so smart or oh so pleasant.
-- Elwood's Mom
.

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