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142 | # Lab 24: The Emotion Table -- Pattern Recognition
#
# Look hard at lab 19. It has seven functions -- draw_happy, draw_sad,
# draw_angry, and four more -- and every single one has the same three
# lines in the same order: set the eyes, set the eyebrows, set the mouth.
# Only the NUMBERS change.
#
# Spotting that is PATTERN RECOGNITION, and it pays off immediately. If
# seven functions differ only in their numbers, then the numbers are the
# real content and the function is just packaging. So put the numbers in a
# table, write the packaging once, and let one function draw all seven.
#
# Lab 19 needs about 50 lines to define seven emotions. The table below
# does it in eight, and an eighth emotion costs one more line -- no new
# code at all.
import config
import face
button_a, button_b = config.init_buttons()
# --- one more column --------------------------------------------------
#
# The table below gained a COLOR column, and that is the whole point of
# this paragraph. Adding it required no new drawing code, no new
# function, and no change to draw_emotion() beyond unpacking one more
# name. That is what "the numbers are the real content" buys you: a
# brand-new axis of expression costs one column.
#
# The colors are built with config.color565(red, green, blue), which
# takes three ordinary 0-255 values. Lab 32 takes that function apart and
# shows you what it does to them.
WHITE = config.WHITE
SOFT_BLUE = config.color565(120, 170, 255)
SOFT_RED = config.color565(255, 110, 110)
VIOLET = config.color565(200, 160, 255)
LIME = config.color565(150, 230, 120)
# One row per emotion. Read the columns straight across:
#
# name eye_rx eye_ry brow_L brow_R lift mouth style size_x size_y color
#
# eye_rx / eye_ry are the eye's width and height. A tall eye reads as
# alert, a squashed one as angry or bored. brow_L / brow_R tilt the inner
# ends down when positive; lift raises the whole brow.
#
# The geometry numbers are roughly two and a half times the OLED kit's,
# because the screen is roughly two and a half times as wide -- but they
# are not a straight multiplication. The OLED was half as tall as it was
# wide, so its faces were squashed. Here they are not.
#
# Note that Contempt is deliberately left WHITE. "No color" is a design
# choice too, and a table that lets you say so is a better table.
EMOTIONS = (
("Happy", 24, 24, 0, 0, 5, face.SMILE, 50, 24, config.YELLOW),
("Sad", 22, 22, -7, -7, 0, face.FROWN, 40, 20, SOFT_BLUE),
("Angry", 24, 12, 12, 12, -5, face.FLAT, 26, 0, SOFT_RED),
("Afraid", 31, 31, -12, -12, 7, face.OPEN, 15, 22, VIOLET),
("Surprised", 32, 32, 0, 0, 14, face.OPEN, 20, 26, config.CYAN),
("Disgusted", 22, 15, 10, -5, -3, face.SNEER, 30, 18, LIME),
("Contempt", 24, 24, 0, 0, 0, face.SMIRK, 34, 0, WHITE),
# ("Bored", 24, 10, 0, 0, -7, face.FLAT, 28, 0, config.GREEN),
)
def draw_emotion(row):
"""Draw ANY row from the table above. This is the only drawing code in
the lab -- the seven expressions are data, not seven functions."""
(name, eye_rx, eye_ry, brow_l, brow_r, lift,
style, size_x, size_y, color) = row
face.clear()
face.set_color(color)
face.eyes(eye_rx, eye_ry)
face.eyebrows(brow_l, brow_r, lift)
face.mouth(style, size_x, size_y)
face.label(name, color=WHITE) # the caption stays white, always
# The shell gets the row too, so you can see the data that produced
# the picture. This is the habit lab 26 turns into a real tool.
print("drawing", name, row[1:])
index = 0
draw_emotion(EMOTIONS[index])
while True:
if face.pressed(button_a):
index = (index + 1) % len(EMOTIONS)
draw_emotion(EMOTIONS[index])
face.wait_for_release(button_a)
if face.pressed(button_b):
index = (index - 1) % len(EMOTIONS)
draw_emotion(EMOTIONS[index])
face.wait_for_release(button_b)
# Things to try:
#
# 1. Uncomment the "Bored" row. You just added an emotion to the menu
# without writing one line of drawing code. Now invent your own row.
#
# 2. Make "Sad" sadder by editing only its numbers -- try eye_ry 17 and
# brow tilt -12. You are tuning a face the way a designer would, by
# changing values instead of rewriting code.
#
# 3. Give one emotion a lopsided brow: set brow_L to 12 and brow_R to -7
# on Contempt and see how much a single mismatched eyebrow changes the
# meaning.
#
# 4. Sort the table so the emotions run from most positive to most
# negative. Because they are data, sorting the menu is just reordering
# lines -- something that would be a real edit in lab 19.
#
# 5. Push one emotion's eye_rx up until the eyes touch the bezel. Write
# down the number. That is the widest eye this screen can hold at
# face.EYE_SPACING, and it is a fact about the hardware, not the code.
#
# 6. Set every color in the table to WHITE and step through the menu
# again. Can you still tell the seven emotions apart? You should be
# able to -- the shapes were doing that work before the colors
# existed. Color is allowed to REINFORCE an expression. It must never
# be the only thing carrying it.
#
# Two reasons that rule is not fussiness:
#
# Roughly one boy in twelve has a red-green color deficiency, so an
# angry-red-versus-happy-green scheme fails for someone in most
# classrooms. And color survives a photograph, a video call, and a
# bright window far worse than a shape does.
#
# 7. Try config.BLUE (pure 0x001F) on one emotion, then SOFT_BLUE, and
# look at them from across the room. Pure blue is startlingly dim.
# Your eye gets most of its brightness from green light and almost
# none from blue, so a "blue" face is a dark face. That is why the
# colors above are pale mixes rather than pure channels -- every one
# of them has plenty of green in it.
#
# 8. Add a color column to lab 28's POSES table the same way, so the
# robot's mood changes hue as its state machine moves. One column,
# again, and no new drawing code -- which is the same lesson arriving
# for the third time.
|
Seven functions that differ only in their numbers were never seven functions — they were one function and a table, waiting to be noticed.