USING: arrays kernel math sequences
locals
math.order math.vectors
accessors
opengl opengl.gl ui ui.gadgets ui.gadgets.canvas ui.render ;
IN: dragon

! : zig ( p1 p2 -- p1 pI p2 )
!     [ [ first2 ] bi@
!       [ [ rot swap + swap ] dip - + 2 / ] 4keep
!       [ rot + swap ] dip + + 2 / 2array
!     ] 2keep [ swap ] dip ;

! : zag ( p1 p2 -- p1 pA p2 )
!     [ [ first2 ] bi@
!       [ [ rot swap + swap ] dip + - 2 / ] 4keep
!       [ rot swap - swap ] dip + + 2 / 2array
!     ] 2keep [ swap ] dip ;

:: zig ( p1 p2 -- p1 pI p2 )
    p1 first2 :> ( x1 y1 )
    p2 first2 :> ( x2 y2 )
    p1
    x1 x2 + y1 y2 - + 2 /
    x2 x1 - y1 y2 + + 2 / 2array p2 ;

:: zag ( p1 p2 -- p1 pA p2 )
    p1 first2 :> ( x1 y1 )
    p2 first2 :> ( x2 y2 )
    p1
    x1 x2 + y1 y2 + - 2 /
    x1 x2 - y1 y2 + + 2 / 2array p2 ;

! : dragon' ( p1 p2 p3 d -- seq )
!     dup zero? [
!         2drop 2array
!     ] [
!         1 - swap dupd swap [ dupd swap ] 2dip ! p1 p2 d p2 p3 d
!         [ zig ] 4dip [ zag ] dip ! p1 pI p2 d p2 pA p3 d
!         [ dragon' ] 4dip dragon' ! p1 pI p2 d dragon' / p2 pA p3 d dragon'
!         append
!     ] if;

:: dragon' ( p1 p2 p3 d -- seq )
    d zero? [
        p1 p2 2array
    ] [
        p1 p2 zig d 1 - dragon'
        p2 p3 zag d 1 - dragon'
        append
    ] if ;

: dragon ( -- seq )
    { 100 100 } { 356 100 } zig 15 dragon' ;

! ---

: draw-dragon ( n -- )
    1 glLineWidth
    1 glPointSize
    1.0 1.0 1.0 1.0 glColor4d
    drop
    GL_LINE_STRIP glBegin
    dragon [ first2 glVertex2d ] each
    glEnd ;

TUPLE: dragon-canvas < canvas ;

M: dragon-canvas layout* delete-canvas-dlist ;
M: dragon-canvas draw-gadget* [ dim>> first2 min 3 /i draw-dragon ] draw-canvas ;
M: dragon-canvas pref-dim* drop { 430 300 } ;

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

MAIN: dragon-window