--
-- Animate a Sprite around a Circle
-- Ken Loge - http://diginoodles.com
--

property pVal -- use to increment position value
property pOrigLoc -- the original location of the sprite
property pVel -- sprite velocity
property pRadius -- the radius of the circle

on beginSprite me
  -- store original location of sprite
  pOrigLoc = sprite(me.spriteNum).loc
end

on getPropertyDescriptionList me
  list = [:]
  addProp list, #pRadius, [#comment: "Radius of Circular Movement:", #format: #integer, #default: 180, #range: [#min: 0, #max: 300]]
  addProp list, #pVel, [#comment: "Velocity:", #format: #integer, #default: 2, #range: [#min: -30, #max: 30]]
  return list
end

on exitFrame me
  -- keep value within 360 degrees
  pVal = (pVal + pVel) mod 360
  
  -- compute x,y position around a circle
  a = float((pVal - 90.0) / 360.00) * 6.2832
  x = cos(a) * pRadius
  y = sin(a) * pRadius
  -- move the sprite
  sprite(me.spriteNum).loc = point(x + pOrigLoc.locH, y + pOrigLoc.locV)
end