add a new renderer called delta with phase modulation

src/shimmers/sketches/pendulum_sway.cljs

@@ -45,10 +45,22 @@
                    (* r dampen1 (math/sin (+ (* 6 dampen2) (* fy t)))))
           (v/polar (* 0.04 r dampen2) (* 4 t)))))
 
+(defn delta [r t {:keys [lambda1 lambda2 dx dy gamma-rate]}]
+  (let [dampen1 (math/exp (* (- lambda1) t))
+        dampen2 (math/exp (* (- lambda2) t))
+        fx (+ dx (* 0.00025 (math/sin (* gamma-rate t))))
+        fy (+ dy (* 0.00025 (math/cos (* gamma-rate t))))]
+    (tm/+ (gv/vec2 (* r dampen1 (math/cos (+ (* 6 dampen2) (* fx t)
+                                             (* 0.005 (math/sin (* 0.2 t))))))
+                   (* r dampen1 (math/sin (+ (* 6 dampen2) (* fy t)
+                                             (* 0.005 (math/cos (* 0.2 t)))))))
+          (v/polar (* 0.04 r dampen2) (* 4 t)))))
+
 (def functions
   {:alpha alpha
    :beta beta
-   :gamma gamma})
+   :gamma gamma
+   :delta delta})
 
 (defn plot [{:keys [p r]} {:keys [select-fn] :as params}]
   (let [limit 100
@@ -68,7 +80,8 @@
                circles))
 
 (defn gen-parameters []
-  {:select-fn (dr/weighted [[:alpha 1.0] [:beta 2.0] [:gamma 1.5]])
+  {:select-fn (dr/weighted [[:alpha 1.0] [:beta 2.0]
+                            [:gamma 1.5] [:delta 1.0]])
    :dx (+ (dr/random-int 1 6) (dr/random -0.01 0.01))
    :dy (+ (dr/random-int 1 6) (dr/random -0.01 0.01))
    :lambda1 0.004