USING: arrays math math.constants math.functions namespaces kernel
opengl.gl locals ui.gadgets.canvas ui.gadgets ui.render accessors
sequences math.order ui prettyprint math.vectors ;

IN: dragon ! http://rosettacode.org/wiki/Dragon_curve#BASIC

SYMBOLS: point angle ;

: trn ( d -- )
    pi * 180 / angle get + angle set ;

: draw-fwd ( p -- ) ! this is still kinda ugly, TODO fancy colors
    dup point get swap point get v+
    GL_LINES glBegin [ first2 glVertex2d ] bi@ glEnd
    point get v+ point set ;

: fwd ( l -- )
    [ angle get cos * ]
    [ angle get sin * ] bi 2array draw-fwd ;

:: dragon' ( l s d -- )
    s zero? [
        l fwd
    ] [
        d 45 * trn
        l 2 sqrt / s 1 -  1 dragon'
        d neg 90 * trn
        l 2 sqrt / s 1 - -1 dragon'
        d 45 * trn
    ] if ;

: dragon ( n -- ) drop ! artifact from maze.factor i don't understand but breaks
    1 glLineWidth
    1.0 1.0 1.0 glColor3d
    0 angle set
    { 150 180 } point set
    400 12 1 dragon' ;

! --- there be dragons beyond this, no idea why i have to do some of this

TUPLE: dragon-canvas < canvas ;

M: dragon-canvas draw-gadget* [ dim>> first2 min 3 /i dragon ] draw-canvas ;
M: dragon-canvas pref-dim* drop { 640 480 } ;

MAIN-WINDOW: dragon-window { { title "Dragon Curve" } }
  dragon-canvas new-canvas >>gadgets ;

MAIN: dragon-window