;btw go board: 234,213,153
(setq yellow    (/ 1 6.0)
      green   (/ 2 6.0)
      cyan  (/ 3 6.0)
      blue    (/ 4 6.0)
      magenta (/ 5 6.0)
      red     1.0
      )
;note that 1530.0=255.0 * 6.0
(defun rgbstr (tt)
 (cond
   ((and (>= tt 0.0)(<= tt yellow));moving from red to yellow
    (strcat
      "255,";full red
      (itoa (fix (+ 0.5 (* tt 1530.0)))) ",";green increases to full
      "0";no blue
      )
    )
   ((<= tt green);moving from yellow to green
    (strcat
      (itoa (fix (+ 0.5 (* (- green tt) 1530.0)))) ",";red decreases
      "255,";full green
      "0";no blue
      )
    )
   ((<= tt cyan);moving from green to cyan
    (strcat
      "0,";no red
      "255,";full green
      (itoa (fix (+ 0.5 (* (- tt green) 1530.0))));blue increases
      )
     )
   ((<= tt blue);moving from cyan to blue
    (strcat
        "0,";no red
       (itoa (fix (+ 0.5 (* (- blue tt) 1530.0)))) ",";green decreases
	"255";full blue
	)
    )
   ((<= tt magenta);moving from blue to magenta
    (strcat
      (itoa (fix (+ 0.5 (* (- tt blue) 1530.0)))) ",";red increases
      "0,";no green
      "255";full blue
      )
    )
   ((<= tt red);moving from magenta to red (home)
       (strcat
    "255,";full red
    "0,";no green
    
      (itoa (fix (+ 0.5 (* (- red tt) 1530.0))));blue decreases
      )
    )
   (t "128,128,128");tt out of bounds - return neutral gray
   );end cond
  );end defun
(defun test ()
  (setq x 0.0)
  (while (< x 1.0)
    (terpri)
    (princ x)(princ ":  ")(princ (rgbstr x))
    (setq x (+ x 0.05))
    )
  )
(defun c:test ()
 (setq x 0)
 (while (< x 100.0) 
  (command "pline" (list x 0.0)(list x 100.0) ""
	   "pedit" (entlast) "w" 1.0 ""
	   "chprop" (entlast) "" "c" "t"
	             (rgbstr (* 0.01 x))
	           ""
	   )
   (setq x (+ x 1.0))
   )
  )