LUA: Turning the wheels of a windmill

-- Interface
comp_interface = getObject("Interfaces[Kompass]")

-- Lokale Interface-Koordinaten des Kompassnadel-Drehpunktes
rot_point = {55;85}

-- Anzahl Sprites
num_sprites = 64

-- Geschwindigkeit (1=sofort; je größer, je langsamer)
rot_speed = 5




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-- Aktuelle Position des Kompasses
pos_compass = {0;0}

-- Aktueller Winkel
curr_angle = 0

--Dreht die Kompassnadel in Richtung des Mauszeigers
function spinNeedle()
   local pos_cursor = getCursorPos()

   local target_angle = math.atan2(pos_compass[2] - pos_cursor.y, pos_compass[1] - pos_cursor.x) / math.pi * 180
   local rot_angle = target_angle - curr_angle
   if rot_angle <= -180 then
      rot_angle = 360 + rot_angle
   elseif rot_angle > 180 then
      rot_angle = 360  - rot_angle
   end
   curr_angle = curr_angle + rot_angle / rot_speed

   if curr_angle < 0 then
      curr_angle = 360 + curr_angle
   elseif curr_angle >= 360 then
      curr_angle = curr_angle - 360
   end
   local call_frame = math.floor(curr_angle / 360 * num_sprites + 0.5) + 1
   if call_frame == 65 then call_frame = 1 end

   comp_anim:setValue(VAnimationFirstFrame, call_frame)
   comp_anim:setValue(VAnimationLastFrame, call_frame)
end


-- Speichert die Position des Kompass-Drehpunktes in einer globalen Variable
function setRotationPoint()
   local int_pos = comp_interface:getPoint(VInterfacePosition)
   pos_compass = {int_pos.x + rot_point[1];int_pos.y + rot_point[2]}
end