# -*- tcl -*- tcl.tk//DSL diagram//EN//1.0
# Knowledge about demo environment here ... Need in-language control
# for the controller, or the 'new direction' etc. commands.
::D new direction b1 angle 210 opposite b4
::D new direction b2 angle 270 opposite b5
::D new direction b3 angle 330 opposite b6
::D new direction b4 angle  30 opposite b1
::D new direction b5 angle  90 opposite b2
::D new direction b6 angle 150 opposite b3

proc benzene {{size {}}} {
    if {$size eq {}} {
	variable movelength
	set size $movelength
    }
    return [block {
	line from [0 0] \
	    then [by $size 330] \
	    then [by $size  30] \
	    then [by $size  90] \
	    then [by $size 150] \
	    then [by $size 210] \
	    then [by $size 270]
	circle dotted radius [expr {0.7 * $size}] \
	    at [0.5 between [last line 1] [last line 4]]
	# Propagate the ring corners into the block
	foreach p {1 2 3 4 5 6} { set b$p [last line $p] }
    }]
}

proc bond {} { line noturn }

benzene; b3; bond; benzene ; bond ; text text CH3