Pokémon Eon Version

badge_sprite.ox = badge_sprite.width / 2 #sets the sprite to rotate around the centre, not the left side.
angle = (frame * 2 * Math::PI) / max_frame # gets the angle of the sprite in radians.
zoom_x = Math::cos(angle) # circular motion uses sin or cos; I chose cos because it starts with the badge facing the viewer. Ranges between -1 and 1.
if zoom_x > 0 # if zoom_x is positive, the badge is facing towards you; if it's negative, it's facing away.
  badge_sprite.bitmap = front_bitmap 
else
  badge_sprite.bitmap = back_bitmap
end
if (((frame * 4) / max_frame) % 2) == 0 # This is a bit tricky; we need it to be shaded dark in the first and third quarters of the animation, and light in the second and fourth.
  badge_sprite.color.red = 0
  badge_sprite.color.green = 0
  badge_sprite.color.blue = 0
else
  badge_sprite.color.red = 255
  badge_sprite.color.green = 255
  badge_sprite.color.blue = 255
end
badge_sprite.color.alpha = 128 - (zoom_x.abs * 128) # Sets the alpha of the shading colour; zoom_x.abs is the same as zoom_x but disregards the sign (so a negative value becomes positive).
badge_sprite.zoom_x = zoom_x # Finally, sets the sprite's zoom_x. A negative value (when the back is shown) should flip the sprite; if it doesn't, then either flip the image of the back, or set badge_sprite.mirror.