feathers demo for t-display

examples/T-DISPLAY/feathers.py

+"""
+feathers.py
+    Smoothly scroll rainbow colored random curves across the front the LILYGO® TTGO T-Display
+"""
+
+import random
+import math
+import utime
+from machine import Pin, SPI
+import st7789
+
+
+def between(left, right, along):
+    """returns a point along the curve from left to right"""
+    d = (1 - math.cos(along * math.pi)) / 2
+    return left * (1 - d) + right * d
+
+
+def color_wheel(WheelPos):
+    """returns a 565 color from the given position of the color wheel"""
+    WheelPos = (255 - WheelPos) % 255
+
+    if WheelPos < 85:
+        return st7789.color565(255 - WheelPos * 3, 0, WheelPos * 3)
+
+    if WheelPos < 170:
+        WheelPos -= 85
+        return st7789.color565(0, WheelPos * 3, 255 - WheelPos * 3)
+
+    WheelPos -= 170
+    return st7789.color565(WheelPos * 3, 255 - WheelPos * 3, 0)
+
+
+def main():
+    # initialize display
+    tft = st7789.ST7789(
+        SPI(1, baudrate=30000000, sck=Pin(18), mosi=Pin(19)),
+        135,
+        240,
+        reset=Pin(23, Pin.OUT),
+        cs=Pin(5, Pin.OUT),
+        dc=Pin(16, Pin.OUT),
+        backlight=Pin(4, Pin.OUT),
+        rotation=1)
+
+    # enable display and clear screen
+    tft.init()
+
+    height = tft.height()
+    width = tft.width()
+
+    tfa = 40       # top free area
+    bfa = 40       # bottom free area
+
+    scroll = 0
+    wheel = 0
+
+    tft.vscrdef(tfa, width, bfa)
+    tft.vscsad(scroll+tfa)
+
+    tft.fill(st7789.BLACK)
+
+    h = (height >> 1) - 1       # half the height of the dislay
+    interval = 50               # steps between new points
+    increment = 1/interval      # increment per step
+    counter = interval + 1      # step counter, overflow to start
+    current_y = 0               # current_y value (right point)
+    last_y = 0                  # last_y value (left point)
+
+    x_offsets = [59, 89, 119, 149, 179, 209, 239]
+
+    while True:
+        # when the counter exceeds the interval, save current_y to last_y,
+        # choose a new random value for current_y between 0 and 1/2 the
+        # height of the display, choose a new random interval then reset
+        # the counter to 0
+
+        if counter > interval:
+            last_y = current_y
+            current_y = random.randint(0, h)
+            counter = 0
+            interval = random.randint(10, 100)
+
+
+        # clear the first column of the display and scroll it
+        tft.vline(scroll, 0, height, st7789.BLACK)
+        tft.vscsad(scroll+tfa)
+
+        # get the next point between last_y and current_y
+        tween = int(between(last_y, current_y, counter * increment))
+
+        # draw mirrored pixels across the display at the offsets using the color_wheel effect
+        for i, x_offset in enumerate(x_offsets):
+            tft.pixel((scroll+x_offset) % 240, h + tween, color_wheel(wheel+(i<<2)))
+            tft.pixel((scroll+x_offset) % 240, h - tween, color_wheel(wheel+(i<<2)))
+
+        # increment scroll, counter, and wheel
+        scroll += 1
+        scroll %= width
+        counter += 1
+        wheel += 1
+        wheel %= 256
+
+        # pause to slow down scrolling
+        utime.sleep(0.005)
+
+
+main()