love2d엔진 쓰는데요







dw = love.graphics.getWidth()
dh = love.graphics.getHeight()

function love.load()

 music = love.audio.newSource("HorrorPB[1].mp3")
 love.audio.play(music)
 music:setLooping(true)

 world = love.physics.newWorld(-650, -500, 650, 500)
 world:setGravity(0, 50)
 
 imgg = love.graphics.newImage("background.png") 
 imgp = love.graphics.newImage("cha.png")

 gw, gh, gx, gy = dw, 40, 0, dh-40

 objects = {}

 objects.ground={}
 objects.ground.body=love.physics.newBody(world, 650/2, 475, 0, 0)
 objects.ground.shape=love.physics.newRectangleShape(objects.ground.body, 0, 0, 650, 100, 0)
 objects.ground.shape:setData("ground")

 objects.groundd={}
 objects.groundd.body=love.physics.newBody(world, 650/2, -30, 0, 0)
 objects.groundd.shape=love.physics.newRectangleShape(objects.groundd.body, 0, 0, 650, 10, 0)
 objects.groundd.shape:setData("ground")

 pw = imgp:getWidth()
 ph = imgp:getHeight()
 px = 500
 py = dh - ph*2+20

 player = {}
 player.b = love.physics.newBody(world, px, py, 10, 0)
 player.s = love.physics.newRectangleShape(player.b, 0, 0, pw, ph, 0)

 love.graphics.setMode(650,500,false,true,0)

end

function love.update(dt)
 world:update(dt)
 if love.keyboard.isDown("escape") then
  love.event.push(\'q\')
 end
 if love.keyboard.isDown("right") then
  px = math.min(px + (200*dt),dw-imgp:getWidth())
 end
 if love.keyboard.isDown("left") then
  px = math.max(px - (200*dt),0)
 end
 if love.keyboard.isDown(" ")then
  player.b:applyForce(0,-100)
 end
 player.b:setX(px)
end

function love.draw()
 love.graphics.draw(imgg, 0,0)
 love.graphics.draw(imgp,player.b:getX(), player.b:getY())
 love.graphics.setColor(0, 0, 0)
 love.graphics.rectangle("fill", objects.ground.body:getX(),objects.ground.body:getY(),650,100)
 love.graphics.setColor(255, 255, 255)
 love.graphics.polygon("fill", objects.groundd.shape:getPoints())

end

update에서 점프 하고 싶은데 그냥 부스터 단듯이 하늘을 날아요
점프하는데 이차함수 써야한다는데 어떻게 써요?;;