diff --git a/2020/sketch_2020_05_30a/sketch_2020_05_30a.gif b/2020/sketch_2020_05_30a/sketch_2020_05_30a.gif
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diff --git a/2020/sketch_2020_05_30a/sketch_2020_05_30a.pyde b/2020/sketch_2020_05_30a/sketch_2020_05_30a.pyde
new file mode 100644
index 00000000..e81cc6ea
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+++ b/2020/sketch_2020_05_30a/sketch_2020_05_30a.pyde
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+# Sigmoid easing by *intro
+
+def setup():
+    size(400, 400)
+    strokeWeight(3)
+
+def draw():
+    background(200)
+
+    #  cinza = map(mouseX, 0, width, 0, 255)
+    #  x = map(mouseX, 0, width, 100, 300)
+    #  pode ser expresso em forma de t para usar lerp()
+    t = map(mouseX, 0, width, 0, 1)
+    cinza = lerp(0, 255, t)
+    x = lerp(100, 300, t)
+    fill(cinza)
+    stroke(0, 0, 200)
+    circle(x, height * .33, 100)
+
+    e = sigmoidMap(t, 0, 1, 0, 1)
+    e_cinza = lerp(0, 255, e)
+    e_x = lerp(100, 300, e)
+    y = lerp(0, height, e)
+    fill(e_cinza)
+    stroke(200, 0, 0)
+    circle(e_x, height * .66, 100)
+
+    for i in range(1 + mouseX):
+        y = sigmoidMap(i, 0, width, 0, height)
+        stroke(200, 0, 0)
+        point(i, y)
+        stroke(0, 0, 200)
+        point(i, map(i, 0, width, 100, 300))
+
+# From John @introscopia
+def sigmoidMap(value, start1, stop1, start2, stop2):
+    c = 6
+    m = map(value, start1, stop1, -c, c)
+    return ((stop2 - start2) * (1 / (1 + exp(-m)))) + start2
diff --git a/2020/sketch_2020_05_31a/gif_export.py b/2020/sketch_2020_05_31a/gif_export.py
new file mode 100644
index 00000000..c505c6ea
--- /dev/null
+++ b/2020/sketch_2020_05_31a/gif_export.py
@@ -0,0 +1,51 @@
+# -*- coding: utf-8 -*-
+
+"""
+Alexandre B A Villares http://abav.lugaralgum.com - v2020_05_31 - Licensed under GPL v3
+Inspired by an example by Art Simon https://github.com/APCSPrinciples/AnimatedGIF/
+
+This is a helper for the Processing gifAnimation library https://github.com/extrapixel/gif-animation/tree/3.0
+Download the library from github.com/extrapixel/gif-animation/archive/3.0.zip 
+Unzip and copy the gifAnimation folder into your libraries folder, like shown below:
+user/sketchbook/libraries/gifAnimation (Linux) 
+user/Documents/Processing/libraries/gifAnimation (Mac/Windows) 
+
+# This file should be saved as a 'tab' named gif_export.py in your Processing Python Mode sketch
+# Restart the IDE and add these lines at the start of your sketch:
+add_library('gifAnimation')
+from gif_export import gif_export
+
+# then add this at the end of draw():
+gif_export(GifMaker, "filename")
+
+"""
+
+def gif_export(GifMaker,             # gets a reference to the library
+               filename="exported",  # .gif will be added
+               repeat=0,             # 0 makes it an "endless" animation
+               quality=255,          # quality range 0 - 255
+               delay=170,            # this is quick
+               frames=0,             # 0 will stop only if 'e' key pressed
+               finish=False):        # force stop
+    global gifExporter
+    try:
+        gifExporter
+    except NameError:
+        gifExporter = GifMaker(this, filename + ".gif")
+        gifExporter.setRepeat(repeat)
+        gifExporter.setQuality(quality)
+        gifExporter.setDelay(delay)
+        print("gif recording started")
+
+    gifExporter.addFrame()
+
+    if frames == 0:
+       if keyPressed and key=='e':
+           finish = True
+    elif frameCount >= frames:
+        finish = True
+                
+    if finish:
+        gifExporter.finish()
+        print("gif saved, exit")
+        exit()
diff --git a/2020/sketch_2020_05_31a/sketch_2020_05_31a.gif b/2020/sketch_2020_05_31a/sketch_2020_05_31a.gif
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index 00000000..baeb0f4f
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diff --git a/2020/sketch_2020_05_31a/sketch_2020_05_31a.pyde b/2020/sketch_2020_05_31a/sketch_2020_05_31a.pyde
new file mode 100644
index 00000000..4faeb8a3
--- /dev/null
+++ b/2020/sketch_2020_05_31a/sketch_2020_05_31a.pyde
@@ -0,0 +1,197 @@
+# Exploring https://easings.net/
+# https://gist.github.com/zeffii/c1e14dd6620ad855d81ec2e89a859719
+import inspect
+
+add_library('gifAnimation')
+from gif_export import gif_export
+
+i = 0
+easing_func = []  # easing functions
+
+def setup():
+    global l1, l2, f1, f2
+    size(600, 400)
+    f1 = createFont("DejaVu Sans Mono Bold", 24)
+    f2 = createFont("Inconsolata Bold", 11)
+
+    l1 = createGraphics(width, height)
+    l1.beginDraw()
+    l1.blendMode(REPLACE)
+    l1.colorMode(HSB)
+    l1.strokeWeight(5)
+    l1.endDraw()
+
+    l2 = createGraphics(width, height)
+    l2.beginDraw()
+    l2.blendMode(REPLACE)
+    l2.colorMode(HSB)
+    l2.endDraw()
+
+def draw():
+    global i
+    background(240)
+    h, w = 330, 600
+    x = (2 * frameCount) % w
+    t = map(x, 0, w, 0, 1)
+    y = height - (height - h) / 2 - h * easing_func[i](t)
+
+    l1.beginDraw()
+    l1.stroke(i * 24, 255, 200)
+    l1.fill(i * 24, 255, 200)
+    l1.point(x, y)
+    l1.endDraw()
+
+    l2.beginDraw()
+    l2.clear()
+    l2.fill(i * 24, 255, 255)
+    l2.strokeWeight(3)
+    l2.circle(width / 2, y, 40)
+    l2.endDraw()
+
+    draw_func_names(l2)
+    draw_def(l2)
+
+    image(l1, 0, 0)
+    image(l2, 0, 0)
+
+    gif_export(GifMaker, "filename")
+    if x + 2 >= w:
+        i = (i + 1) % len(easing_func)
+        delay(1000)
+        if i == 0:
+            background(240)
+            draw_func_names(l2, all=True)
+            image(l1, 0, 0)
+            image(l2, 0, 0)
+            noLoop()
+
+def keyPressed():
+    background(0)
+    loop()
+
+
+def draw_def(pg):
+    source = inspect.getsource(easing_func[i])
+    a_def = unicode(source[23:], 'utf8')
+    pg.beginDraw()
+    pg.fill(0)
+    pg.textFont(f2)
+    pg.textSize(12)
+    pg.text(a_def, 330, 200)
+    pg.endDraw()
+
+def draw_func_names(pg, all=False):
+    pg.beginDraw()
+    if all:
+        n = len(easing_func)
+        pg.clear()
+    else:
+        n = i + 1
+    pg.textFont(f1)
+    pg.textSize(12)
+    for ic in range(n):
+        pg.fill(ic * 24, 255, 255)
+        pg.text(easing_func[ic].__name__, 15, 25 + ic * 22)
+    pg.endDraw()
+
+def register(lst):
+    def wrapper(f):
+        lst.append(f)
+        return f
+    return wrapper
+
+@register(easing_func)
+def double_exponential_sigmoid(x, a=.7):
+    """ 
+    from Golan Levin
+    https://github.com/golanlevin/Pattern_Master
+    """
+    min_param_a = 0.0 + EPSILON
+    max_param_a = 1.0 - EPSILON
+    a = 1 - constrain(a, min_param_a, max_param_a)
+    y = 0
+    if x <= 0.5:
+        y = ((2.0 * x) ** (1.0 / a)) / 2.0
+    else:
+        y = 1.0 - ((2.0 * (1.0 - x)) ** (1.0 / a)) / 2.0
+    return y
+
+def sigmoid_easing(p, const=12):
+    """ from John @introscopia """
+    m = map(p, 0, 1, -const, const)
+    return 1 / (1 + exp(-m))
+
+@register(easing_func)
+def sigmoid_easing(p, const=6):
+    """ from John @introscopia """
+    m = map(p, 0, 1, -const, const)
+    return 1 / (1 + exp(-m))
+
+# From John @introscopia
+def sigmoidMap(value, start1, stop1, start2, stop2):
+    c = 10
+    m = map(value, start1, stop1, -c, c)
+    return ((stop2 - start2) * (1 / (1 + exp(-m)))) + start2
+
+# @register(easing_func)
+# def cubic_ease_in(p):
+#     return p ** 3
+
+# @register(easing_func)
+# def quadratic_ease_in(p):
+#     return p ** 2
+
+# @register(easing_func)
+# def sine_in_out(p):
+#     return -(cos(PI * p) - 1) / 2
+
+# @register(easing_func)
+# def quadratic_ease_in_out(p):
+#     if p < 0.5:
+#         return 2 * p ** 2
+#     return -2 * p ** 2 + (4 * p) - 1
+
+# @register(easing_func)
+# def cubic_ease_in_out(p):
+#     if p < 0.5:
+#         return 4 * p ** 3
+#     else:
+#         f = ((2 * p) - 2)
+#         return 0.5 * f ** 3 + 1
+
+# @register(easing_func)
+# def exponential_in_out(p):
+#     if p == 0.0 or p == 1.0:
+#         return p
+#     if p < 0.5:
+#         r = 2 ** ((20 * p) - 10) / 2
+#     else:
+#         r = -0.5 * 2 ** ((-20 * p) + 10) + 1
+#     return r
+
+# @register(easing_func)
+# def linear(p):
+#     return p
+
+# @register(easing_func)
+# def quadratic_ease_out(p):
+#     return -(p * (p - 2))
+
+# @register(easing_func)
+# def cubic_ease_out(p):
+#     f = (p - 1)
+#     return f ** 3 + 1
+
+# @register(easing_func)
+# def circular_ease_out(p):
+# return sqrt((2 - p) * p)
+
+# @register(easing_func)
+# def back_ease_in_out(p):
+#     c1 = 1.70158
+#     c2 = c1 * 1.525
+#     p2 = p * 2
+#     if p < 0.5:
+#         return (p2 ** 2 * ((c2 + 1) * p2 - c2)) / 2
+#     else:
+#         return ((p2 - 2) ** 2 * ((c2 + 1) * (p2 - 2) + c2) + 2) / 2