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;;;; examples/13-canvas-drawing-language.lisp
(defpackage #:ww.examples/12
(:use #:cl)
(:export #:start))
(in-package :ww.examples/12)
(defclass canvas-lang-demo (ww:application) ())
(ww:defhandler quit
(ww::on-keydown (app scancode)
(when (eql :scancode-q scancode)
(ww::stop))))
(ww:defhandler clear-and-draw
(ww::on-perframe (canvas time)
(ww::clear-canvas canvas :r 255 :g 255 :b 255)
(draw-stuff canvas)
(ww::blit canvas)))
;; draw a triangle, each side is a different color
(defun triangle-at (x y)
(ww::move-to x y)
(ww::canvas-pen-color (list 0 200 200 255))
(ww::stroke-rel 150 0)
(ww::canvas-pen-color (list 0 0 200 255))
(ww::stroke-rel -50 100)
(ww::canvas-pen-color (list 0 200 0 255))
(ww::stroke-rel -100 -100))
;; draw a filled triangle using the current pen
(defun filled-triangle-at (x y)
(ww::move-to x y)
(ww::fill-rel-path
'((100 100)
(100 -100))))
;; a pen function - gets more blue the closer x y is to 0 0
(defun lower-the-bluer (x y)
(list (* 256 (/ x 500))
(* 256 (/ y 500))
255
255))
;; a pen function - makes a plaid like pattern
(defun plaid1 (x y)
(list (mod (* x x) 256)
(mod (* y y) 256)
(mod (* x y) 256)
255))
;; draws a "flower" like pinwheel using bezier curves
(defun flower (&optional (petals 5))
(ww::canvas-pen-width 1)
(let ((r ; radius
(sqrt (+ (* 25 25) (* 100 100))))
(psw ; petal semi-width
(* pi 0.08)))
;; for each angle a between 0 and 2π draw a petal as a bezier
;; curve. the curve uses two control points that are R away from
;; the starting point and PSW radians on either side of the line
;; at angle a
(loop for a from 0 to (* 2 pi) by (/ (* 2 pi) petals)
for ls = (list (list (* r (sin (- a psw)))
(* r (cos (- a psw))))
(list (* r (sin (+ a psw)))
(* r (cos (+ a psw))))
(list 0 0))
do
(ww::fill-rel-bezier ls 12)
(ww::with-pen (:color (list 0 0 0 255) :width 1)
(ww::stroke-rel-bezier ls 12)))))
(defun draw-stuff (canvas)
(ww::with-canvas canvas
;; set canvas color.
(ww::canvas-pen-color #'plaid1)
(filled-triangle-at 250 200)
;; temporarily use a different pen configuration
(ww::with-pen (:color #'lower-the-bluer :width 2)
;; draw a flower stem
(ww::stroke-bezier
'((0 0) (200 120) (50 350) (200 100) (300 400))
12)
;; draw a flower
(flower 28))
(dotimes (x 50)
(when (evenp x)
(triangle-at 30 (+ 250 x))))))
(defmethod ww:boot ((app canvas-lang-demo ))
(let ((canvas
(make-instance 'ww:canvas
:pixel-width 500
:pixel-height 500)))
;; stretch canvas over the whole app
(setf (ww:width canvas) (ww::application-width app)
(ww:height canvas) (ww::application-height app))
;; add it to the display tree
(ww:add-unit app canvas)
;; handlers
(ww:add-handler canvas #'clear-and-draw)
(ww:add-handler app #'quit)
(ww:add-handler canvas #'quit)))
(defun start (&optional (side 500))
(ww::start
(make-instance
'canvas-lang-demo
:fps 10
:width side
:height side
:title "Canvas demo")))
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