function param1()
  return "筆圧透明度", 0, 1, 0
end

function use_base()
  return true
end

function main( x, y, p )

  if firstDraw then
    firstDrawX = x
    firstDrawY = y
  end

  local w = bs_width()
  if w < 0.25 then
    w = 0.25
  end

  local updateDist = w / 4
  if w > 20 then
    updateDist = w/10
  end
  if w > 100 then
    updateDist = w/14
  end

  if not firstDraw then
    local distance = bs_distance( lastDrawX - x, lastDrawY - y )
    if distance < updateDist then
      return 0
    end
  end

  local r,g,b = bs_fore()

  local a = bs_opaque() * 255
  if bs_param1() == 1 then
    a = p * a
  end

  bs_ellipse( x,y, w,w, 0, r,g,b, a )

  local bsx,bsy = bs_base()
  local noInit = (bsx == -1) and (bsy == -1)
  if noInit then
    bsx = firstDrawX
    bsy = firstDrawY
  end
  bs_ellipse( bsx - (x - bsx), y, w,w, 0, r,g,b, a )

  lastDrawX = x
  lastDrawY = y
  firstDraw = false

  return 1
end

bs_setmode( 1 )
lastDrawX = 0
lastDrawY = 0
firstDraw = true

firstDrawX = 0
firstDrawY = 0