diff --git a/src/shimmers/math/equations.cljc b/src/shimmers/math/equations.cljc
index 06b6a06e..915e8dd1 100644
--- a/src/shimmers/math/equations.cljc
+++ b/src/shimmers/math/equations.cljc
@@ -179,3 +179,6 @@
 
 (comment
   (map (fn [x] [x (flatstep x 1.2)]) (range 0 1 0.1)))
+
+(defn inv-smoothstep [x]
+  (- 0.5 (math/sin (/ (math/asin (- 1.0 (* 2.0 x))) 3.0))))
diff --git a/src/shimmers/sketches/cilia_phase.cljs b/src/shimmers/sketches/cilia_phase.cljs
index e0e3853b..8bfc524b 100644
--- a/src/shimmers/sketches/cilia_phase.cljs
+++ b/src/shimmers/sketches/cilia_phase.cljs
@@ -100,7 +100,8 @@
                 (+ 0.025 (eq/gaussian amp 0.5 -0.125 y)))
              :pts
              [(dr/weighted {:equal 1.0
-                            :gaussian 1.0})
+                            :gaussian 1.0
+                            :inv-smooth 1.0})
               (dr/weighted {150 1.0 200 5.0 250 4.0
                             300 2.0 400 0.75 600 0.25})]
              :phase
@@ -136,7 +137,10 @@
                :equal (range -0.05 1.05 (/ 1.0 density))
                :gaussian
                (dr/gaussian-range (/ 1.0 density) (/ 1.0 (eq/sqr density))
-                                  true [-0.05 1.05]))
+                                  true [-0.05 1.05])
+               :inv-smooth
+               (for [x (tm/norm-range density)]
+                 (eq/inv-smoothstep x)))
              cilia
              (cilias {:samples samples
                       :screen-space screen