Add startup animation to drum rack example

firmware/examples/nanogrid-drum-rack/main.py

@@ -107,9 +107,9 @@ while not m.is_open():
 # TX constants
 CHANNEL = 0
 PITCH_C1 = 37
-CONTROLLER = 64
+# CONTROLLER = 64
 
-control_val = 0
+# control_val = 0
 
 def init_btns():
     row_pins = [
@@ -154,17 +154,53 @@ turned_on = set()
 
 (set_led, show_all) = init_leds()
 
-# for i in range(NUM_LEDS):
-#     set_led(i, CYAN)
-#     for j in range(NUM_LEDS):
-#         if i != j:
-#             set_led(j, BLACK)
-#     show_all()
-#     time.sleep(2)
-# 
 
-CYAN = (0, 255, 255)
-BLACK = (0, 0, 0)
+C_ACTIVE = (140, 60, 140)
+C_INACTIVE = (0, 0, 0)
+
+def shader(x, y, t):
+    st_x = float(x + 0.5) / NUM_COL
+    st_y = float(y + 0.5) / NUM_ROW
+    inv_t = 0.5 * (1.0 - t)
+
+    if st_x < t or st_y < t or (1.0 - st_x) < t or (1.0 - st_y) < t:
+        if t < 0.5:
+            return (
+                int(C_ACTIVE[0] * 0.5 * t),
+                int(C_ACTIVE[1] * 0.5 * t),
+                int(C_ACTIVE[2] * 0.5 * t),
+            )
+        if t >= 0.5:
+            return (
+                int(C_ACTIVE[0] * inv_t),
+                int(C_ACTIVE[1] * inv_t),
+                int(C_ACTIVE[2] * inv_t),
+            )
+
+    return C_INACTIVE
+
+def play_animation(dur_s, fps):
+    cur_ms = float(0)
+    dur_ms = dur_s * 1000
+    interval_ms = int(1000 / fps)
+    processing_ms = 200
+
+    while cur_ms < dur_ms:
+        for r in range(0, NUM_ROW):
+            for c in range(0, NUM_COL):
+                t = cur_ms / dur_ms
+                color = shader(c, r, t)
+                set_led(c + r * NUM_COL, color)
+        show_all()
+
+        cur_ms += interval_ms + processing_ms
+        time.sleep_ms(interval_ms)
+
+    for l in range(NUM_LEDS):
+        set_led(l, C_INACTIVE)
+        show_all()
+
+play_animation(3, 10)
 
 print("Starting loop...")
 while m.is_open():
@@ -196,13 +232,13 @@ while m.is_open():
 
     for key in to_turn_on:
         m.note_on(CHANNEL, PITCH_C1 + key - 1)
-        set_led(key, CYAN)
+        set_led(key, C_ACTIVE)
         turned_on.add(key)
 
     for key in to_turn_off:
         m.note_off(CHANNEL, PITCH_C1 + key - 1)
         turned_on.remove(key)
-        set_led(key, BLACK)
+        set_led(key, C_INACTIVE)
 
     show_all()