More flexible sketch class generation

[Kevinpgalligan]

It would be nice if we could share functionality between sketches, and also if the sketch could be instantiated with user-supplied parameters. For this I suggest an alternative defsketch interface, while keeping the old one for simplicity / backward compatibility.

Example defsketchx interface (x is for "extended", maybe?):

(defsketchx my-sketch (some-mixin-class another-mixin-class)
    ;; These can be passed by the user to make-instance
    (x (y 100))
    ((width 200)
     (height 400))
   (circle (or x 50) y))

Then instantiation might look like (make-instance 'my-sketch :x 70 :y 120). Maybe some-mixin-class hooks into draw and always provides a black background.

The specific application I have in mind is having a widgets-window class that automatically creates a separate window with sliders/buttons to modify the sketch parameters.

(defsketchx my-sketch (widgets-window) ()
    ((x (widget:slider 0 width))
     (y (widget:dropdown 10 50 100)))
  (circle (widget:get-value x) (widget:get-value y) 10))

[Gleefre]

As a workaround this could be achieved using the stealth-mixin library.

(defclass widgets-mixin ...)

(defsketch my-sketch (...)
  ...)

(stealth-mixin:add-mixin 'widgets-mixin 'my-sketch)

[Gleefre]

An example:

(defpackage #:sketch-user
  (:use #:cl)
  (:local-nicknames (#:s #:sketch)))

(in-package #:sketch-user)


(defclass black-background-mixin () ())

(defmethod s:draw :before ((sketch black-background-mixin) &key &allow-other-keys)
  (s:background s:+black+))

(s:defsketch test ()
  (s:circle 200 200 100))

(make-instance 'test)

(sleep 5)

(stealth-mixin:add-mixin 'black-background-mixin 'test)