VirtualRelativeJoystick.lua

-- VirtualRelativeJoystick for Gideros
--
-- Onscreen joystick that only appears when lower left quadrant
-- of screen is touched
--

VirtualRelativeJoystick = Core.class(Sprite)


function VirtualRelativeJoystick:init(options)
  self.x = options.x or 100
  self.y = options.y or 100
  self.outerRadius = options.outerRadius or 100
  self.outerCircle = self:getNewCircle(self.outerRadius, false)
  self:addChild(self.outerCircle)
  self.innerNubbin = self:getNewCircle(self.outerRadius * .5, true)
  self:addChild(self.innerNubbin)
  self:setPosition(self.x, self.y)
  self:setVisible(false)
  self:addEventListener(Event.TOUCHES_BEGIN, self.onTouchesBegin, self)
  self.xpos, self.ypos, self.strength, self.angle = 0, 0, 0, 0
end

--
function VirtualRelativeJoystick:onTouchesCancel(e)
  self:onTouchesEnd(e)
end

--
function VirtualRelativeJoystick:onTouchesBegin(e)
  if e.touch.x > application:getContentWidth() * .5 or
     e.touch.y < application:getContentHeight() * .5 then return end
  self:addEventListener(Event.TOUCHES_MOVE, self.onTouchesMove, self)
  self:addEventListener(Event.TOUCHES_END, self.onTouchesEnd, self)
  self.controlTouchId = e.touch.id
  self:setPosition(e.touch.x, e.touch.y)
  self:setVisible(true)
  e:stopPropagation()
end

--
function VirtualRelativeJoystick:onTouchesMove(e)
  if e.touch.id == self.controlTouchId then
    local x, y = self:globalToLocal(e.touch.x, e.touch.y)
    local radius = self.outerRadius
    local distance = math.sqrt(x * x + y * y)
    -- normalized strength for use with angle
    self.strength = (distance >< radius) / radius
    self.angle = ^>math.atan2(y, x) + 90.
    x = (x <> -radius) >< radius
    y = (y <> -radius) >< radius
    self.xpos, self.ypos = x / self.outerRadius, -y / self.outerRadius
    self.innerNubbin:setPosition(x, y)
    e:stopPropagation()
  end
end

--
function VirtualRelativeJoystick:onTouchesEnd(e)
  if e.touch.id == self.controlTouchId then
    self:removeEventListener(Event.TOUCHES_MOVE, self.onTouchesMove, self)
    self:removeEventListener(Event.TOUCHES_END, self.onTouchesEnd, self)
    self.innerNubbin:setPosition(0, 0)
    self.xpos, self.ypos = 0, 0
    self:setVisible(false)
    e:stopPropagation()
  end
  self.controlTouchId = nil
end

--
function VirtualRelativeJoystick:getNewCircle(radius, filled)
  local p = Path2D.new()
  r = radius
  p:setSvgPath(("M %s 0 a %s %s 0 0 0 %s 0 a %s %s 0 0 0 %s 0 Z"):format(-r, r, r, 2*r, r, r, -2*r))
  p:setLineThickness(10) -- Outline width
	p:setFillColor(0xdddddd, filled and .6 or .0) --Fill color
	p:setLineColor(0xdddddd, .6) --Line color
  return p
end