08. Arrow，Jump，Tiles

3.4，摆烂，海斗，继续 Sheepolution 的教程。

Angle

function love.update(dt)
    local mx, my = love.mouse.getPosition()

    arrow.angle = math.atan2(my - arrow.y, mx - arrow.x)
    dx = math.cos(arrow.angle)
    dy = math.sin(arrow.angle)

    local dist = math.sqrt((mx - arrow.x) ^ 2 + (my - arrow.y) ^ 2)
    if dist > 20 then
        arrow.x = arrow.x + dx * arrow.speed * dt
        arrow.y = arrow.y + dy * arrow.speed * dt
    end
end

function love.draw()
    love.graphics.draw(
        arrow.image,
        arrow.x, arrow.y,
        arrow.angle,
        1, 1,
        arrow.originX, arrow.originY
    )
end