Draw a sphere: Difference between revisions

{{trans|Java}}

<lang PicoLisp>(scl 24)

(setq *Shades

(list "." ":" "!" "*" "o" "e" "&" "#" "%" "@"))

(setq *Light

(list 30.0 30.0 -50.0))

(de normalize (V)

(let Len

(sqrt

(sum

(quote (X)

(** X 2))

V))

(mapcar

(quote (X)

(*/ X 1.0 Len))

V)))

(de dot (X Y)

(let D (sum (quote (A B) (*/ A B 1.0)) X Y)

(if (< D 0) (- D) 0)))

(de floor (N)

(* 1.0 (*/ (- N 0.5) 1.0)))

(de ceil (N)

(* 1.0 (*/ (+ N 0.5) 1.0)))

(de drawSphere (R K Ambient)

(let Vec NIL

(for (I (floor (- R)) (<= I (ceil R)) (+ I 1.0))

(let X (+ I 0.5)

(for (J (floor (* -2 R)) (<= J (ceil (* 2 R))) (+ J 1.0))

(let Y (+ (/ J 2) 0.5)

(if (<= (+ (*/ X X 1.0) (*/ Y Y 1.0)) (*/ R R 1.0))

(prog

(setq Vec

(list X Y

(sqrt

(* 1.0

(- (*/ R R 1.0)

(*/ X X 1.0)

(*/ Y Y 1.0))))))

(setq Vec (normalize Vec))

(let (B NIL

Intensity NIL)

(setq B (+ (/ (** (dot *Light Vec) K) (** 1.0 (- K 1))) Ambient))

#(println (format (/ (** (dot *Light Vec) K) (** 1.0 (- K 1))) *Scl))

(setq Intensity

(if (<= B 0)

(- (length *Shades) 2)

(max (format (round (*/ (- 1.0 B) (* (- (length *Shades) 1) 1.0) 1.0) 0)) 0)))

(prin (nth *Shades (+ Intensity 1) 1))))

(prin " "))))

(prinl)))))

(setq *Light (normalize *Light))

(drawSphere 20.0 4 0.1)

(drawSphere 10.0 2 0.4)</lang>