Chapter 1 Exercise 3

notebooks/chapter_1.md

@@ -40,3 +40,19 @@ What's important is that we introduce the [`[thi.ng.geom.vector]`](https://cljdo
 Why did I choose to pull in `thi.ng/geom` rather than use p5.js's `createVector` and other associated functions?
 
 Well, Quil doesn't expose these functions because the P5.js and Processing APIs for vectors is not at all compatible. Furthermore I want the code in this notebook to be more or less Clojure and Clojurescript compatible. The `thi.ng/geom` library provides a bunch of tools that we will use in the future.
+
+
+## Exercises 1.1 and 1.2
+
+I am skipping these exercises as they don't add much to what we did in Example 1
+
+## [Exercise 1.3: Bouncing Sphere](https://natureofcode.com/vectors/#exercise-13)
+
+
+```clojure
+^{::clerk/no-cache true ::clerk/viewer clerk/code}
+(slurp "src/noc/chapter_1_3e.cljs")
+(show-sketch :c1.3e)
+```
+
+This was more an exercise in 3d than vectors, haha! I fake the boundary condition for the sphere, but it looks more or less right.

src/noc/chapter_1_3e.cljs

@@ -0,0 +1,43 @@
+(ns noc.chapter-1-3e
+  (:require
+   [thi.ng.math.core :as tm]
+   [thi.ng.geom.vector :as v]
+   [quil.core :as q]))
+
+(def size [640 300])
+
+(defn init-state [{:keys [width height] :as state}]
+  {:angle 0.0
+   :pos (v/vec3 0 0 0)
+   :vel (v/vec3 2 2.5 3)
+   :thresh 75})
+
+(defn setup! [{:keys [width height]}]
+  (q/background 255)
+  (q/no-fill))
+
+(defn tick [{:keys [angle pos vel thresh]}]
+  (let [[x y z] (tm/+ pos vel)
+        [vx vy vz] vel
+        angle (+ angle 0.05)
+        vx (if (> (abs x) thresh) (* vx -1) vx)
+        vy (if (> (abs y) thresh) (* vy -1) vy)
+        vz (if (> (abs z) thresh) (* vz -1) vz)]
+    {:pos (tm/+ pos vel)
+     :thresh thresh
+     :vel (v/vec3 vx vy vz)
+     :angle angle}))
+
+(defn draw! [{:keys [pos angle]}]
+  (let [[x y z] pos]
+    (q/background 255)
+    (q/directional-light 255 255 255 1 1 -1)
+    (q/stroke 0)
+    (q/box 200)
+    (q/push-matrix)
+    (q/translate x y z)
+    (q/rotate-x angle)
+    (q/rotate-y angle)
+    (q/stroke 0)
+    (q/sphere 30)
+    (q/pop-matrix)))

src/noc/sketch.cljs

@@ -20,7 +20,8 @@
             [noc.chapter-0-9e :as c0.9e]
             [noc.chapter-0-10e :as c0.10e]
             [noc.chapter-1-1 :as c1.1]
-            [noc.chapter-1-2 :as c1.2]))
+            [noc.chapter-1-2 :as c1.2]
+            [noc.chapter-1-3e :as c1.3e]))
 
 (def sketches
   {:walker (sketch-> c0.1)
@@ -39,7 +40,8 @@
    :c0.9e (sketch-> c0.9e)
    :c0.10e (sketch-3d-> c0.10e)
    :c1.1 (sketch-> c1.1)
-   :c1.2 (sketch-> c1.2)})
+   :c1.2 (sketch-> c1.2)
+   :c1.3e (sketch-3d-> c1.3e)})
 
 (defn load-sketch [s]
   (when-let [sk (get sketches s)]
@@ -148,14 +150,12 @@
 
 (defn show-sketch [adjust-frame {:keys [init setup tick draw size] :as opts} el]
   {:applet (apply q/sketch (apply concat
-                                  (doto
-                                   (-> opts
-                                       (assoc :middleware [m/fun-mode])
-                                       (assoc :host el)
-                                       (assoc :update (partial tick-wrapper tick))
-                                       (assoc :setup (partial setup-wrapper (partial adjust-frame el) init setup))
-                                       (assoc :draw (partial draw-wrapper draw)))
-                                    prn)))
+                                  (-> opts
+                                      (assoc :middleware [m/fun-mode])
+                                      (assoc :host el)
+                                      (assoc :update (partial tick-wrapper tick))
+                                      (assoc :setup (partial setup-wrapper (partial adjust-frame el) init setup))
+                                      (assoc :draw (partial draw-wrapper draw)))))
    :sketch-name (:sketch-name opts)
    :opts opts
    :el el})