fix comet going too far off left and right edges

Author: rhooper

adafruit_led_animation/animation/comet.py

@@ -84,8 +84,8 @@ def __init__(
         self._computed_color = color
         self._num_pixels = len(pixel_object)
         self._direction = -1 if reverse else 1
-        self._left_side = -self._tail_length - 1
-        self._right_side = self._num_pixels + self._tail_length + 1
+        self._left_side = -self._tail_length
+        self._right_side = self._num_pixels
         self._tail_start = 0
         self.reset()
         super().__init__(pixel_object, speed, color, name=name)
@@ -105,17 +105,16 @@ def _comet_recompute_color(self, color):
 
     def draw(self):
         for pixel_no in range(self._tail_length + 1):
-            draw_at = self._tail_start + (self._direction * pixel_no)
+            draw_at = self._tail_start + pixel_no
             if draw_at < 0 or draw_at >= self._num_pixels:
                 continue
-            self.pixel_object[draw_at] = self._comet_colors[pixel_no]
+            self.pixel_object[draw_at] = self._comet_colors[pixel_no * self._direction]
 
         self._tail_start += self._direction
 
-        if self._tail_start < self._left_side or self._tail_start > self._right_side:
+        if self._tail_start < self._left_side or self._tail_start >= self._right_side:
             self.reverse = not self.reverse
             self._direction = -self._direction
-            self._tail_start += self._direction
             if self.reverse == self._initial_reverse:
                 self.cycle_complete = True