Hi Casey, you may want to prevent the canvas element from being re-rendered. You could remove any reagent atom references in the canvas holder, and use a ref to redraw the quil scene (this could be hooked up to a normal atom with a watcher to get the reactive experience when data changes)

> use a ref to redraw the quil scene How does one do this? (i'm ctrl-f-ing in the quil api docs, but not finding anything)

Hm even the :update opt doesn't seem to be documented in defsketch

My component looks like: (defn canvas [state] (r/create-class {:component-did-mount (fn [component] (let [node (r/dom-node component) width (/ (.-innerWidth js/window) 2) height (/ (.-innerHeight js/window) 2)] (q/sketch :host node :draw draw :setup (init-canvas width height state) :size [width height] :middleware [m/fun-mode]))) :render (fn [] [:div])})) And the holder looks like: (defn canvas-holder [(let [sketch-state @(rf/subscribe [:query-sketch-state])] [:div [do-stuff-button] [(canvas sketch-state)]])])

ah i mean a react ref to reference the element, think it would look like this:

(defonce my-canvas (atom nil))

(defn ui []
  [:div
    [:canvas {:ref (fn [el] (reset! my-canvas el))}]])

(defonce color (atom "red"))

(add-watch color :watcher
  (fn [key atom old-state new-state]
    (when @my-canvas
      (let [ctx (.getContext @my-canvas "2d")]
        (.beginPath ctx)
        (.rect ctx 10 10 20 20)
        (set! ctx -fillStyle @color)
        (.fill ctx)))))

Ah interesting add-watch is a clojure core thing, I've never used it before

now that I look at https://github.com/yogthos/quil-reagent-demo/blob/master/src/circles_demo/core.cljs though.. maybe you're meant to set up a quil :update function, then never actually trigger a re-render in the holder?

Yea, I based mine off that demo.

I wish there was a pure functional 2d canvas library heh